Detailed Description
The invention is further described below with reference to specific preferred embodiments, without thereby limiting the scope of protection of the invention.
The heterotrophic nitrification-aerobic denitrification paracoccus strain used in the following examples is deposited in Guangdong province culture Collection (GDMCC) with the deposit number GDMCC NO: 60338. the paracoccus GDMCC NO: 60338 was named Paracoccus LJ2(Paracoccus versutus LJ 2).
1) Separating and screening strains
The paracoccus LJ2 of the present example was obtained by screening mainly the following methods:
100mL of activated sludge collected from Longjin sewage plant of Longyan city, Fujian province is added into 200mL of denitrification enrichment medium, and sterile glass beads are added into the medium. 30 ℃, 150rpm min-1Shaking the shaking table, continuously culturing for 5 days, transferring the bacterial suspension into fresh DM culture medium with an inoculum size of 10%, and repeating the culture twice in the culture manner to obtain enriched bacterial suspension.
0.2mL of the enriched bacterial suspension was plated on DM agar medium (1.5% agar) using a 10-fold dilution method and incubated at 30 ℃. Bacterial colonies with significantly different characteristics were selected and streaked to obtain single colonies. The purified colonies were re-inoculated in fresh agar medium. Culturing the isolated strain in KNO3And (3) performing primary screening in a DM primary screening culture medium which is a unique nitrogen source, and inoculating the strain capable of surviving in the DM primary screening culture medium into an LB slant culture medium for preservation at the temperature of-4 ℃. Then, the primary screening strain NH was measured4 +-N and NO3 -And (4) obtaining a strain LJ2 with better denitrification performance by the N-removing rate and then researching.
2) Strain identification
The identification process and the results of the paracoccus LJ2 strain of the embodiment are as follows:
2.1) morphological identification
The morphological structure of the microorganism is observed by a visual observation method, an optical microscope observation method and a projection electron microscope observation method.
The colony morphology of the strain LJ2 on beef extract peptone medium is shown in FIG. 1: the bacterial colony is milk white, the edge is neat, the circle is slightly raised, the surface is smooth and moist, and the bacterial colony is opaque. Gram-negative bacteria were identified as LJ-2 gram stain. The transmission electron microscope image of LJ2 is shown in FIG. 2: the thallus is in a short rod shape, has no capsule, no spore and no flagellum, and the transverse diameter of LJ2 is about 0.49 μm and the length is about 1.07 μm.
2.2) physiological and biochemical identification
The typical method for classifying bacteria in detail is based on the results of physiological and biochemical tests, and the physiological and biochemical characteristics of the strains in the test are tested according to the literature and Bergeming Manual of bacteria identification.
The physiological and biochemical characteristics of the strain LJ2 were determined, and the results are shown in Table 3: the sugar fermentation experiments of LJ2 are negative, and do not produce acid or gas; the catalase and oxidase experiments are positive, and the physiological and biochemical characteristics of LJ2 and Paracoccus (Paracoccus versutus) are preliminarily judged to be consistent:
TABLE 3 physiological and biochemical experimental characteristics of Strain LJ2
Name of experiment
|
Results of the experiment
|
Name of experiment
|
Results of the experiment
|
Oxidase enzyme
|
+
|
V.P
|
-
|
Contact enzyme
|
+
|
Hydrolysis of fats and oils
|
+
|
Oxidative fermentation of glucose
|
-
|
Oxidation of acetic acid
|
-
|
Lactose oxidative fermentation
|
-
|
Milk with litmus
|
Acid production
|
Hydrolysis of urea
|
-
|
Indole experiments
|
+
|
Starch hydrolysis
|
-
|
Amino acid decarboxylase
|
-
|
Methyl Red
|
-
|
Nitrate reduction
|
- |
Note: in the table, "+" indicates positive, there was a reaction; "-" indicates negative, no such reaction. In the sugar fermentation experiment, "o +" means acid and gas production; "+" indicates no gas is produced when acid is produced; "-" indicates no acid or gas production.
2.3) molecular biological identification
In the experiment, bacterial genome DNA is extracted from the bacterial strain DNA according to the operation steps of the Ezup column type bacterial genome DNA extraction kit.
2.3.1) amplification and sequencing of the 16S rRNA Gene
The bacterium contains three kinds of ribosomal RNA, 5S rRNA, 16S rRNA and 23S rRNA. The relative molecular weight of the 16S rRNA gene is moderate, the reproducibility of sequence analysis is extremely high, and the 16S rRNA gene is one of the most common methods in the systematic classification research of bacteria. At present, the 16S rRNA gene is generally used as a target for sequence analysis to identify the bacterial species. In the experiment, 16S rRNA of the strain is subjected to PCR amplification by using universal primers 27F and 1492R, and sequencing is performed after purification.
The PCR reaction system for the 16S rRNA gene is shown in Table 4.
Table 416S rRNA Gene PCR reaction System
10×PCR buffer
|
2.5μL
|
dNTP
|
0.5μL
|
F
|
0.5μL
|
R
|
0.5μL
|
Taq enzyme
|
0.25μL
|
ddH2O
|
20.75μL
|
Total
|
25μL |
The PCR amplification result of the 16SrRNA gene is shown in FIG. 3, the fragment length is about 1400bp, and the amplification position of the band is correct. The results of the sequencing analysis are shown in FIG. 4: the similarity between the strain LJ-2 and the Paracoccus (Paracoccus vereutus) is 99 percent, so that the strain LJ2 is judged to be a Paracoccus (Paracoccus versutus) and is named as Paracoccus versutus LJ 2.
2.3.2) functional Gene identification
In the aerobic denitrification process, the periplasmic nitrate reductase gene (nap gene) can be preferentially expressed under the aerobic condition, and NO is3 -The N does not need to pass through the cell membrane to reach the active region of the periplasmic nitrate reductase, which is capable of directly converting NO3 -Reduction of-N to NO2 --N; nitric oxide reductase (NOSZ) is capable of converting NO2 -Reduction of-N to N2Also plays a key role in the denitrification process of bacteria. Therefore, in order to further verify the aerobic denitrification function of the strain, the experiment carries out PCR amplification on the periplasmic nitrate reductase gene (napA, the fragment length is 800 bp-900 bp) and the nitric oxide reductase gene (nosZ, the fragment length is about 300bp) of the strain, wherein primer pairs used in the PCR are nap1/nap2(nap 1: 5 '-TCTGGACCATGG-GCTTCAACCA-3', nap 2: 5'-ACGACGACCGGCCAGCGCAG-3') and nosZ-F/nosZ-R (nosZ-F: 5 '-CGYTGTTCMTCGACAGCCAG-3', nosZ-R: 5 '-CGSACCTTSTTGCCSTYGCG-3').
The PCR reaction procedure for 16S rRNA, napA gene, and nosZ gene is shown in Table 5.
TABLE 516 PCR reaction procedure for S rRNA, napA Gene, nosZ Gene
The electrophoresis result of the gene amplified fragment of the LJ2 strain is shown in FIG. 5: the obtained specific band with the fragment size of about 700 bp-1000 bp is consistent with the size of the predicted fragment, so that the bacterium can be preliminarily judged to contain the napA gene, which shows that the strain LJ2 has the function of reducing NO3 -Conversion of-N to NO2 --function of N.
The gene of the LJ2 strain is amplified by using the primer nos1/nos2, and the electrophoresis result of the amplified fragment is shown in FIG. 6: the obtained specific band with the fragment size of about 250 bp-500 bp is consistent with the predicted size. Therefore, it was also judged that the bacterium contained the nosZ gene, indicating that the strain LJ2 has NO converting ability2 -Conversion of-N to N2The function of (c).
The paracoccus LJ2 of the embodiment has good heterotrophic nitrification-aerobic denitrification performance and high carbon-nitrogen ratio resistance, and can be used for denitrification treatment of ammonia nitrogen, nitrate nitrogen and nitrite nitrogen in high C/N wastewater. When the method is applied, firstly, the paracoccus LJ2 is prepared into paracoccus LJ2 seed liquid, and then, the wastewater denitrification treatment is carried out, wherein the paracoccus LJ2 seed liquid is prepared by adopting the following method:
inoculating the strain into LB liquid culture medium, culturing in 30 deg.C constant temperature shaking table for 48 hr, pouring the bacterial liquid in LB culture medium into centrifuge tube, centrifuging at 4000rpm for 10min, collecting thallus, cleaning thallus with sterile water for three times, and adjusting OD with sterile water600To 0.6-0.8 of bacterial suspension to prepare seed liquid.
The formula of the culture medium used is as follows:
denitrification enrichment medium (DM) (g.L)-1):Na2HPO4·7H2O 7.9,KH2PO4 1.5,NH4Cl 0.3, MgSO4·7H2O 0.1,(CH2COONa)2·6H2O 4.7,KNO30.3, 2 mL. L of trace element solution-1。
DM prescreening medium (g.L)-1):Na2HPO4·7H2O 7.91,KH2PO4 1.5,MgSO4·7H2O 0.1,(CH2COONa) 2·6H2O 4.7,KNO30.3, 2 mL. L of trace element solution-1
Solution of trace elements (g.L)-1):EDTA 50,ZnSO4 2.2,CaCl2 5.5,MnCl2·4H2O 5.1,FeSO4·7H2O 5.0,(NH4)6Mo7O24·4H2O 1.1,CuSO4·5H2O 1.6,CoCI2·6H2O 1.6。
Heterotrophic nitrification medium (g.L)-1):(NH4)2SO4 0.24,(CH2COONa)2·6H2O2.25, Vickers salt solution 50 mL. L-1。
Aerobic denitrification culture medium (g.L)-1):KNO3 0.36,(CH2COONa)2·6H2O2.25, Vickers salt solution 50 mL. L-1。
Aerobic nitrosation culture medium (g.L)-1):NaNO2 0.25,(CH2COONa)2·6H2O2.25, Vickers salt solution 50 mL. L-1。
Vickers salt solution (g.L)-1):K2HPO4 5.0,MgSO4·7H2O 2.5,NaCl 2.5,MnSO4·4H2O 0.05, FeSO4·7H2O 0.05。
LB liquid Medium (g.L)-1): tryptone 10, yeast extract 5, NaCl 10, pH 7.0.
Note: all liquid culture media are sterilized for 20min at the temperature of 121 ℃ for later use, and 1.5-2% of agar is added into the solid culture media.
The experimental instruments used in the examples are shown in table 1:
TABLE 1 Experimental apparatus
Device name
|
Model number
|
Manufacturer of the product
|
Biochemical incubator
|
SHP-250 type
|
Shanghai Sensin laboratory instruments Ltd
|
Ultraviolet spectrophotometer
|
UV-1800
|
Shanghai Mapada Instruments Co.,Ltd.
|
Clean workbench
|
SW-CJ-1F
|
SUZHOU ANTAI AIRTECH Co.,Ltd.
|
Vertical automatic high-pressure sterilizing pot
|
HVE-50
|
XIAMEN BAIJIA BIOTECHNOLOGY Co.,Ltd.
|
Air culture shaking table
|
SPH-100B
|
SHIPING OSCILLATOR
|
Ultramicro spectrophotometer
|
MULTISKAN-GO
|
Saimer Feishale science and technology (China) LimitedCompany(s)
|
Gradient PCR instrument
|
MULTISKAN-GO
|
THERMO FISHER SCIENTIFIC (CHINA) Co.,Ltd.
|
High-capacity high-speed refrigerated centrifuge
|
ST16R
|
THERMO FISHER SCIENTIFIC (CHINA) Co.,Ltd.
|
Binocular microscope
|
BA210
|
MOTIC CHINA GROUP Co.,Ltd. |
The water quality testing and analyzing items and methods in the examples are shown in table 2:
TABLE 2 items and methods of Water quality testing analysis
Example 1:
a method for treating ammonia nitrogen wastewater by using the heterotrophic nitrification-aerobic denitrification paracoccus strain LJ2 seed liquid comprises the following steps:
inoculating the seed liquid of the strain into heterotrophic nitrification culture medium at 3%, shaking-culturing at 150rpm and 30 deg.C for 48 hr, and measuring NH content of the culture medium every 6 hr4 +-N、NO3 --N、NO2 -N and COD content and pH and OD600And drawing the above indexesCurve change diagram of (2).
Strain LJ2 as NH4 +N is a unique nitrogen source, the growth condition and the heterotrophic nitrification denitrification performance change law after 48 hours of culture are shown in figure 7: the growth curve changes greatly within 0-12 h, and the growth curve is in the exponential growth phase of LJ 2; after 12h, the growth curve tends to be flat, and LJ2 enters a growth stabilization phase; 42h, the growth curve reaches the peak, OD600A maximum value of 0.28; 48h, OD600In a downward trend, LJ2 enters the growth decline phase. The pH value is gradually increased along with the culture time, and is increased from 7.05 to 8.50, which indicates that the strain LJ2 produces alkali during the growth process. NH of the strain LJ2 in 0-6 h4 +N begins to degrade, NO2 --N starts to accumulate; 12h, NH4 +The removal rate of-N reaches 100 percent, NO2 -The accumulated amount of-N is about 2.25 mg.L-1;24h,NO2 -The accumulated amount of-N reaches 2.87 mg.L-1; 36h,NO2 --N is completely removed; 42h, the COD removal rate reaches the maximum 90.42 percent; no NO is generated in the whole heterotrophic nitrification process3 --accumulation of N. The concept of the conventional nitration reaction indicates the nitration of NH by bacteria4 +N should be converted to NO3 --N or NO2 --N. In this experiment, NO3 --N is not accumulated and NO2 -The small accumulation of N and the removal of N indicate that LJ2 can simultaneously carry out nitration and denitrification reactions, and the intermediate product generated in the nitration process can be used as the substrate of the denitrification process.
In conclusion, strain LJ2 can utilize NH4 +N grows and has denitrification performance, and the nitrogen removal rate can reach 100 percent, which indicates that LJ2 has excellent heterotrophic nitrification capability.
Example 2:
in this example, the content of ammonium sulfate as a nitrogen source was fixed, sodium succinate was used as a carbon source, and the carbon-nitrogen ratio was varied by adjusting the content of the carbon source. C/N was set to 8, 10, 15, 20, 25, 30, 35, 40, 50, 60, 100 and 150, 3 replicates were set for each set of experiments, the other components of the heterotrophic nitrification medium and the culture conditions were unchanged at 150rpmShaking culture at 30 deg.C for 24 hr, and determining OD in different culture media600、NH4 +N and TN contents.
The effect of C/N on heterotrophic nitrification performance of LJ2 is shown in FIG. 8: C/N is in the range of 8-150, NH of LJ24 +the-N removal rate can reach more than 85 percent. Wherein OD of LJ2 when C/N is 35600A maximum of 0.953, NH4 +The removal rate of-N was 92.83%, and the removal rate of TN was 80.87%. OD when C/N increases to 40600Down to 0.843, NH4 +the-N removal rate is reduced to 91.03%, and the TN removal rate is reduced to 78.35%, which shows that the denitrification capability of LJ2 is reduced along with the increase of C/N. However, when C/N is further increased to 60, OD600Increase to 0.904, NH again4 +The removal rate of-N can reach 92.76%, and the removal rate of TN can reach 85.16%. OD at C/N of 100, 150600Respectively reduced to 0.796, 0.744, NH4 +The N removal rate is 96.43 percent and 95.69 percent, the TN removal rate is 78.26 percent and 67.30 percent, and in conclusion, the C/N range suitable for the growth and denitrification of LJ2 is wide.
Heterotrophic nitrification-aerobic denitrification bacteria usually use organic matter as a carbon source and energy source, but generally, too high C/N inhibits the growth and nitrification of the bacterial strain. The optimum C/N for denitrification of the general heterotrophic nitrification-aerobic denitrification bacteria is 5-8, and less is more than 20. And the C/N range adapted by the strain LJ2 is larger when NH is used4 + N concentration 50 mg.L-1When C/N is 150, NH4 +The N removal rate can still reach 95.69%, which shows that a large amount of carbon source can still enable LJ2 to grow and maintain good denitrification performance, which shows that LJ2 also has stronger NH under high organic load4 +N removal capacity, so that LJ2 can be better applied to the treatment of high organic load wastewater.
Example 3:
NH4 +n as the sole nitrogen source during the growth of ammonia nitrogen oxidizing bacteria, NH in the substrate4 +The concentration of-N is critical for the growth of heterotrophic nitrifying bacteria. NH (NH)4 +Too low a concentration of-N to satisfyThe requirement of the strain for growth and the over-high concentration can cause toxic action on the growth of cells, and simultaneously, the activity of key enzyme in the nitration reaction can be inhibited through a substrate, thereby influencing the nitration activity of heterotrophic nitrifying bacteria. This example investigates the effect of different substrate concentrations on the heterotrophic nitrification performance of a strain.
Based on the modified heterotrophic nitrification medium, the C/N was fixed at 60, and the initial nitrogen concentration of the medium was set at 50 mg. multidot.L-1、 100mg·L-1、200mg·L-1、300mg·L-1、400mg·L-1. Inoculating into culture medium with different nitrogen concentrations according to optimal inoculum size, setting each group for 3 times, culturing at 150rpm and 30 deg.C for 7 days, and measuring OD every day600,NH4 +N and TN contents.
Different NH4 +The effect of-N concentration on the heterotrophic nitrification denitrification performance of LJ2 is shown in FIG. 9: after 7 days of culture, as initial NH4 +N concentration 50 mg.L-1When is NH4 +The removal rate of-N reaches 100 percent, OD600Is 1.011; when initial NH4 +N concentration of 100 mg.L-1When is NH4 +The removal rate of-N also reaches 100 percent, the thallus grows well, and the OD600Is 1.065; but NH4 +-N concentration higher than 100 mg.L-1After that, with initial NH4 +Increase in the concentration of N, NH of the strain LJ24 +The removal rate of-N decreases with the decrease of-N, when NH is initiated4 +-N concentration of 200 mg.L-1When is NH4 +The degrading ability of-N is reduced to 93.76%, but the growth condition of thallus is optimal, and the OD600The value reaches 1.2; when initial NH4 +-N concentration of 300 mg.L-1OD of LJ2600Value is only 0.384, but NH4 +No significant decrease in N removal; when initial NH4 +-N concentration of 400 mg.L-1Then, OD600The value is reduced to 0.246, NH4 +the-N removal rate was reduced to 11.02%. This description follows NH4 +The increase in N concentration, the inhibition of growth and denitrification of the strain LJ 2. LJ2At different NH4 +No NO after 7 days of cultivation at-N concentration3 --N and NO2 -Accumulation of-N indicates that LJ2 has better denitrification performance.
Acinetobacter sp YN3 isolated from Osmunda japonica or the like, with initial NH4 +Increase in N concentration, NH4 +The lower the removal capacity of N, the initial NH4 +-N concentration of 200 mg.L-1When is NH4 +The N removal rate is only 2%; pseudomonas putida LY1 in initial NH4 +N concentration 50 mg.L-1,NH4 +The maximum N removal rate is 64%, with NH4 +Increase in N concentration, NH4 +-a gradual decrease in N removal rate; copper-greedy bacterium cupriavidius sp.S1 tolerant to high-concentration ammonia nitrogen in initial NH4 +-N concentrations up to 200 mg.L-1When is NH4 +the-N removal was 94.98%. With the above-mentioned strain NH4 +Tolerance to NH by LJ2 compared to tolerance to N concentration4 +The concentration of-N reaches 400 mg.L-1And initial NH4 +-N concentration 300 mg.L-1Then is still NH4 +the-N removal rate can still reach more than 90 percent, which indicates that LJ2 has better ammonia nitrogen tolerance capability.
It has been reported that heterotrophic nitrification-aerobic denitrification bacteria of certain species can tolerate higher concentrations of NH4 +-N, but NH thereof4 +The N removal rate is lower, and the concentration of the tolerant organic matters is lower than that of LJ 2. For example: has high NH tolerance4 +-N-capable Acinetobacter sp.y1 when C/N is 14, NH4 +-N concentration 1600 mg.L-1When is NH4 +The N removal rate is only 21.3%; acinetobacter SQ2 at C/N ═ 12, NH4 +-N concentration 1400 mg.L-1Then, OD600The value can reach 2.635, NH4 +the-N removal was only 38.6%. These two strains described above are resistant to high NH4 +The strains with-N concentration all need lower C/N conditions, namely organic matter concentration phaseFor lower cases, lower NH is expressed4 +-N removal rate. Compared with the traditional Chinese medicine composition, the C/N tolerance of LJ2 is as high as 60-150, which is about forty times of that of Y1 and SQ 2. Therefore, LJ2 still has good NH under the condition of high load of organic matter4 +N tolerance and denitrification effect, and has potential application value in the treatment of high-concentration organic nitrogen-containing wastewater.
Example 4:
(1) LJ2 heterotrophic nitrification performance influencing factor
(1.1) Effect of carbon Source on heterotrophic nitrification Performance of strains
Microorganisms can be divided into two broad categories, autotrophic and heterotrophic, depending on their utilization of different carbon sources. Heterotrophic is one in which the microorganisms use organic matter in the environment as carbon nutrients. The ammonia nitrogen removal capacity of heterotrophic nitrifying bacteria is influenced by the type of carbon source. Therefore, the experiment researches the utilization conditions of the strains on different carbon sources.
In the experiment, sodium succinate, sodium acetate, sodium citrate, ethanol, glucose, sucrose and other carbon sources are selected as an experimental group, sodium bicarbonate and carbon-free are selected as a control group, and the influence of the selected carbon sources on the heterotrophic nitrification performance of the strain is inspected. And (3) performing equimolar replacement on a carbon source in the heterotrophic nitrification culture medium, keeping other components unchanged, and preparing various culture media. The seed solutions were inoculated at 3% inoculum size into 250mL Erlenmeyer flasks containing 100mL of different carbon source media (3 replicates for each carbon source). After the inoculated medium was cultured for 24 hours in a shaker at 30 ℃ at 150rpm, the OD in the different media was measured600、NH4 +N and TN contents.
The effect of carbon source on heterotrophic nitrification performance of LJ2 is shown in fig. 10: strain LJ2 in carbon Source free Medium, NH4 +N removal rate was 0 and biomass did not increase, indicating that carbon source is required for growth of LJ 2; the strain LJ2 can grow in the culture medium added with different selected carbon sources, but the utilization of different carbon sources by the strain LJ2 is different, and the OD of the strain LJ2 is the OD of the strain with sodium bicarbonate as the carbon source600Value of 0.229, NH4 +The removal rate of-N was 40.28%, and TN was removedThe rate is 30.34%, which indicates that LJ2 can grow by using inorganic carbon source, but the denitrification performance is weak. OD of LJ2 in the case of a medium containing sodium succinate as a carbon source600Maximum value of 0.34, LJ2 vs NH4 +The removal rates of-N and TN were the greatest, reaching 98.50% and 75.82%, respectively. Therefore, sodium succinate is the best carbon source in the heterotrophic nitrification denitrification process of LJ 2.
(1.2) Effect of pH on the heterotrophic Nitrification Performance of the strains
The pH of the solution is one of the important factors for the growth of the bacteria. The pH value affects the growth performance and nitrification performance of the cells by the action of enzymes in the cells. The microorganisms can grow over a wide pH range, but all have a pH that is most suitable. Therefore, the experiment researches the influence of different initial pH values in the culture medium on the growth performance and ammonia nitrogen degradation capability of the strain.
Adjusting initial pH of the culture medium to 6.5, 7, 7.5, 8, 8.5, and 9 by adding low concentration sodium hydroxide or hydrochloric acid solution, performing shake culture at 150rpm and 30 deg.C for 3 times, and measuring OD of the strain after 24 hr600、 NH4 +N and TN contents.
The effect of pH on heterotrophic nitrification performance of LJ2 is shown in fig. 11: NH of different pH values to LJ24 +the-N removal capability has little influence, but has great influence on the removal capability of TN. OD of LJ2 at pH 6.5600Is 0.867, NH4 +the-N removal was 94.77% and the TN removal was only 74.84%, probably due to NH in the medium4 +N may be converted to NO2 --N or NO3 --N; OD of LJ2 in a pH range of 7-8600The values are 0.869, 0.863, 0.85, NH respectively4 +The removal rates of-N, TN and TN were 95.16%, 92.24% and 93.99%, respectively, and 90.60%, 93.27% and 92.02%, respectively. After a pH value of more than 8, the TN removal rate of LJ2 is obviously reduced. Therefore, the growth condition of LJ2, NH are combined4 +the-N removal rate and the TN removal rate are appropriate, the initial pH value of the culture medium is 7-8, and the optimal pH value is 7.5.
(1.3) Effect of temperature on the heterotrophic Nitrification Performance of the strains
The temperature is an appropriate temperature for an important survival factor of the microorganism to maximize the growth and metabolic rate of the microorganism. The enzyme in the organism has the strongest activity under the condition of proper temperature, the stronger the enzyme activity in the bacteria is, and the stronger the growth performance and the ammonia nitrogen degradation capability are. The experiment researches the influence of different culture temperature conditions on the growth performance and ammonia nitrogen degradation capability of the strain.
Inoculating the seed liquid in an improved heterotrophic nitrification culture medium with an optimal carbon source, ammonium sulfate as a nitrogen source, an optimal carbon-nitrogen ratio and an optimal initial pH value of the culture medium by 3 percent of inoculation amount. The inoculated culture medium was placed at 25 deg.C, 30 deg.C, 35 deg.C, 40 deg.C, 3 replicates were set for each experiment, and after culturing for 24 hours in a shaker at 150rpm, the OD of the strain was measured600、NH4 +N and TN contents.
The effect of different temperatures on the heterotrophic nitrification denitrification performance of LJ2 is shown in FIG. 12: OD of LJ2 at 25 ℃ of culture temperature600Is 0.628, NH4 +The N removal rate is 99.51%, and the TN removal rate is 73.76%; OD of LJ2 at 30 ℃600Is 0.875 NH4 +the-N removal rate can reach 95.15%, and the TN removal rate can reach 92.05%; the temperature is higher than 30 ℃, and the TN removal rate is obviously reduced. In summary, the optimal temperature for growth and denitrification of LJ2 was 30 ℃.
(1.4) Effect of inoculum size on heterotrophic nitrification performance of strains
The effect of deamination and denitrification can not be achieved due to insufficient inoculation amount, and the proper inoculation amount plays an important role in improving the denitrification effect and the practical application. In addition, within a certain range, the inoculation amount of the bacterial strain is properly increased, and the growth lag phase of the bacterial strain can be shortened and even eliminated. Therefore, the experiment researches the influence of the strain inoculation amount on the growth performance and ammonia nitrogen degradation capability of the strain.
Inoculating 3%, 5%, 7%, 10% and 15% of the modified heterotrophic nitrification culture medium respectively. Culturing at 150rpm and 30 deg.C for 3 replicates each, and measuring OD after culturing for 24 hr600、NH4 +N and TN contents.
The effect of the inoculum size on the heterotrophic nitrification performance of LJ2 is shown in fig. 13: OD of LJ2 at 3%, 5%, 7%, 10%, 15% inoculation amount600The pH values are respectively 0.795, 0.837, 0.865 and 0.878, the pH values are respectively 8.49, 8.47 and 8.47, and NH is generated4 +the-N removal rates are respectively 98%, 96% and 96%, and the TN removal rates are respectively 65%, 64%, 55%, 61% and 61%. The above results show that: the effect of different inoculation amounts on the heterotrophic nitrification denitrification capability of the LJ2 is not obvious, namely the denitrification performance is not improved along with the increase of the inoculation amount. An excessively large inoculation amount causes the strain to consume nutrients in the medium too quickly, so that the growth cycle is shortened, and the cost of high inoculation amount and investment is high in economic aspects. Therefore, the heterotrophic nitrification inoculation amount of the LJ2 can be selected to be 3 percent.
(1.5) Effect of dissolved oxygen on heterotrophic nitrification of strains
Different dissolved oxygen concentrations can have a significant effect on the nitrification of the microorganisms and may even control the nitrified metabolites. Research shows that the change of the rotating speed can represent the change of the dissolved oxygen in the culture solution, so that the concentration of the dissolved oxygen in the culture medium can be controlled by adjusting the rotating speed of the shaking table. The experiment inspects the influence of the rotating speed on the growth performance of the strain and the ammonia nitrogen degradation capability.
Inoculating the modified heterotrophic nitrification culture medium according to the optimal inoculation amount. The culture conditions were 0rpm, 90rpm, 150rpm, 180rpm, 30 ℃ respectively, 3 replicates were set for each experiment, and after 24 hours of culture, OD was measured600、NH4 +N and TN contents.
Dissolved Oxygen (DO) increases with increasing rotational speed, enabling growth of aerobic strains. The results of the influence of the rotating speed on the heterotrophic nitrification denitrification performance of LJ2 are shown in FIG. 14: at a rotation speed of 0, i.e. stationary culture, NH4 +The removal rates of-N and TN are 40.26% and 32.23% respectively, which indicates that the ventilation quantity in the culture medium is insufficient, the dissolved oxygen is insufficient, and the growth and denitrification performance of the strain are inhibited; the rotating speed is within 90-150 rpm, and the OD of the strain LJ2 is increased along with the increase of the rotating speed600、NH4 +The removal rate of-N and TN gradually increasesHigh, wherein at 150rpm, NH4 +The N removal rate reaches 100 percent, and the TN removal rate reaches 97.59 percent; when the rotational speed continued to rise to 180rpm, the OD of the strain LJ2600And TN removal decreased to 0.854 and 95.14%, respectively. Therefore, the rotating speed of the heterotrophic nitrification denitrification of LJ2 is selected to be 150 rpm. It is shown that as the rotation speed increases, DO increases, growth and denitrification performance of LJ2 can be promoted, and to a certain extent, excessive DO conversely inhibits growth and denitrification performance of LJ 2.
Example 5:
a method for treating nitrate nitrogen wastewater by using the heterotrophic nitrification-aerobic denitrification paracoccus strain LJ2 seed liquid comprises the following steps:
inoculating the seed liquid of the strain LJ2 into an aerobic denitrification culture medium at a rate of 3%, carrying out shake culture at the temperature of 30 ℃ at the rpm of 150, culturing for 48 hours, and measuring the NH content of the culture medium every 6 hours4 +-N、NO3 --N、NO2 -N and COD content and pH and OD600And drawing a curve change graph of the indexes.
Strain LJ2 with NO3 -N is a unique nitrogen source, the growth condition and aerobic denitrification performance change law after 48 hours of culture are shown in figure 15: the growth curve has large variation amplitude within 0-12 h, and LJ2 enters a growth exponential phase; 12h, the growth curve tends to be flat, and LJ2 enters a growth stabilization phase; OD of 30h600A maximum of 0.329 is reached; 36h, OD600In a downward trend, LJ2 enters the growth decline phase. The pH value is gradually increased along with the culture time, and is increased from 7.38 to 8.49, which indicates that the strain LJ2 produces alkali during the growth process. 0 to 6 hours, NO3 -Beginning of N removal, no NH4 +Accumulation of-N, 0.02 mg.L-1NO of2 --N accumulation; the COD removal rate reaches 83.04% at most after 18 h; 24h, NO3 --N removal of 93.20% maximum; 30h, NH4 +-N accumulation 2.82 mg.L-1;48h,NO3 -The removal rate of-N is reduced to 78.40%, NH4 +The accumulated amount of-N is 0.77 mg.L-1,NO2 --accumulated amount of NIs 0.08 mg.L-1. The above results show that: strain LJ2 can utilize NO3 -N growth and denitrification, NO when LJ2 enters growth decline phase3 -The removal rate of-N is also reduced, and the aerobic denitrification capability of LJ2 is closely related to the growth of the strain.
Taken together, strain LJ2 can utilize NO3 -N grows and has denitrification performance, and the nitrogen removal rate can reach 93.20%, which shows that LJ2 has excellent aerobic denitrification capability.
Example 6:
by using aerobic denitrification medium, NO3 -The concentration of-N was fixed at 50 mg.L-1The carbon concentration was adjusted so that C/N was 8, 15, 30, 60, 120, respectively. Inoculating the strain seed liquid into different C/N culture media according to 3% inoculum size, placing at 150rpm, shake culturing at 30 deg.C, measuring OD 24 hr later600,NO3 --N、NO2 -N and TN contents.
C/N is also one of the important factors affecting denitrification. C/N is too low, so that the carbon source is insufficient, and the growth of the strain is influenced; when the C/N is too high, an excessive carbon source is not utilized by the microorganism, and the too high C/N inhibits the growth and nitrification reaction of the strain. The influence of C/N on the aerobic denitrification performance of LJ2 is shown in FIG. 16: OD of LJ2 at C/N of 60600A value of 0.818 at maximum; when C/N is 15, 30, 60, NO3 -The removal rates of-N and TN reach 100 percent; when the C/N is increased to 120, the TN removal rate is reduced to 91.25%. Therefore, when the C/N is 60, the growth condition of the LJ2 and the aerobic denitrification denitrogenation performance are optimal, which is consistent with the optimal C/N of the heterotrophic nitrification of the LJ-2.
The optimum C/N for denitrification of the aerobic denitrifying bacteria is 5-8, and less is more than 20. Compared with most aerobic denitrifying bacteria, the strain LJ2 has the capability of tolerating higher C/N, and can provide a new strain resource for treating high C/N organic pollution.
Example 7:
adopting aerobic denitrification culture medium, fixing C/N, and making the culture medium produce initial NO3 -adjusting-N to 50 mg.L-1、100mg·L-1、 150mg·L-1、200mg·L-1、250mg·L-1、300mg·L-1. Inoculating the strain seed solution into culture medium with different nitrogen concentrations according to 3% inoculum size, placing at 150rpm, performing shake culture at 30 deg.C for 24 hr, and measuring OD600,NO3 --N、NO2 -N and TN contents.
Different NO3 -The effect of-N concentration on the aerobic denitrification performance of LJ2 is shown in FIG. 17: when NO is present3 --N concentration 100 mg.L-1OD of LJ2600Is 1.083, NO3 -The removal rates of-N and TN are the highest, and are respectively 99.76% and 81.07%; with NO3 -Increase in N concentration, NO3 -The removal rate of-N and TN is reduced; in NO3 --N concentration of 200 mg.L-1When is NO3 --N removal 70.84%; in NO3 -Increasing the concentration of-N to 300 mg.L-1When is NO3 -The N removal rate is 7.83%, and LJ2 still has denitrification capability.
Songyudong separation strain capable of adapting to high-concentration NO3 -Acinetobacter Acinetobacter sp.Y1 of-N, when initially NO3 - N concentration 50 mg.L-1,NO3 --N removal 100%; when NO is present3 -N concentration of 100 mg.L-1,NO3 --N removal 84.4%; when NO is present3 --N concentration of 200 mg.L-1,NO3 -the-N removal rate was 65.3%. LJ2 in comparison to Y1 at initial NO3 --N is 200 mg.L-1When is NO3 -Higher N removal rate, LJ2 more adaptive to high concentration NO than Y13 --N. Research shows that some aerobic denitrifying bacteria can not react on NO3N is more tolerant than LJ2, but the C/N range that it can tolerate is much less than LJ2, for example: pseudomonas stutzeri strain AD-2 in nitrate nitrogen concentration of 100-1000 mg.L-1In the range of (1), NO3 -The removal rate of-N can reach 99%, and NO NO is generated2 -Accumulation of-N, but the C/N tolerated by AD-2 is only 7, much less than C/N60 of LJ 2. In summary, LJ2 has good NO under high organic concentration conditions3 -the-N tolerance capability and denitrification effect are superior to those of the aerobic denitrification strains reported at present.
Example 8:
inoculating the seed liquid of strain LJ2 into aerobic nitrosation culture medium at 3%, shaking-culturing at 150rpm and 30 deg.C for 48 hr, and measuring NH content of culture medium every 6 hr4 +-N、NO3 --N、NO2 -N and COD content and pH and OD600And drawing a curve change graph of the indexes.
Strain LJ2 with NO2 -N is a unique nitrogen source, the growth condition and aerobic nitrosation denitrification performance change rule after 48 hours of culture are shown in figure 18: OD for 0-12 h600The value is greatly increased, and LJ2 enters an exponential growth phase; 12h, OD600The value reaches 0.275 at maximum; the growth curve tends to be flat and the OD tends to be flat after 18-36 h600The value is not changed greatly, and LJ2 enters a growth stabilization phase; OD for 42-48 h600The value drops and LJ2 enters the growth decline phase. The pH value gradually increased with the culture time from 7.92 to 8.78, indicating that the strain LJ2 produces alkali during the growth process. 0 to 6 hours, NO2 -Beginning of N removal, NO3 --N accumulation of 0.28 mg.L-1Is free of NH4 +-N accumulation; 12h, NO3 --N and NH4 +N is not accumulated, and the COD removal rate is 78.40 percent at most; 24h, NO3 --N accumulation 0.28 mg. L-1,NH4 +-N accumulation 1.79 mg. L-1;30h,NO2 -The highest removal rate of-N reaches 64.81 percent, and NH4 +The accumulation amount of-N reaches 4.10 mg.L at most-1;36h,NO2 -The N removal rate decreased to 62.33%; 42-48 h, accumulated NO3 --N and NH4 +-N is completely removed.
Taken together, strain LJ2 can utilize NO2 --N growth with depletionThe nitrogen performance and the nitrogen removal rate can reach 64.81 percent, which shows that LJ2 has the aerobic nitrosation capacity.
Example 9:
adopting aerobic nitrosation culture medium, NO2 -The concentration of-N was fixed at 50 mg.L-1The carbon concentration was adjusted so that C/N was 8, 15, 30, 60, 120, respectively. Inoculating the strain seed liquid into different C/N culture media according to 3% inoculum size, placing at 150rpm, shake culturing at 30 deg.C, measuring OD 24 hr later600,NO3 --N、NO2 -N and TN contents.
C/N is also one of the important factors affecting denitrification. C/N is too low, so that the carbon source is insufficient, and the growth of the strain is influenced; when the C/N is too high, an excessive carbon source is not utilized by the microorganism, and the too high C/N inhibits the growth and nitrification reaction of the strain.
The results of the influence of C/N on the aerobic nitrosation denitrification performance are shown in FIG. 19: NO when C/N is increased from 15 to 302 -The N removal rate is reduced from 100% to 95.08%, and the TN removal rate is increased from 93.38% to 100%; and C/N is 60, NO2 -99.87% of-N and 98.54% of TN removal rate; when the C/N is increased to 120, the TN removal rate is reduced to 88.91%. Therefore, the aerobic nitrosation performance of LJ-2 is best when the C/N is 60, which is consistent with the optimal C/N of heterotrophic nitrification and aerobic denitrification of LJ 2.
The optimum C/N for denitrification of the aerobic denitrifying bacteria is 5-8, and less is more than 20. Compared with most aerobic denitrifying bacteria, the strain LJ2 has the capability of tolerating higher C/N, and can provide a new strain resource for treating high C/N organic pollution.
Example 10:
adopting aerobic nitrosation culture medium, fixing C/N, adding NO into culture medium2 -The concentration of-N is adjusted to 50 mg.L-1、100mg·L-1、150 mg·L-1、200mg·L-1、250mg·L-1、300mg·L-1. Inoculating the strain seed solution into culture medium with different nitrogen concentrations according to 3% inoculum size, placing at 150rpm, performing shake culture at 30 deg.C for 24 hr, and measuring OD600,NO2 --N、NO3 -N and TN contents.
Different NO2 -The influence of-N concentration on the aerobic nitrosation denitrification performance of LJ2 is shown in FIG. 20: NO2 --N concentration 50 mg.L-1Then, OD600Is 0.796, NO2 -The removal rates of-N and TN are the highest, and are respectively 100% and 76.04%; with NO2 -Increase in N concentration, NO2 -Reduced removal of-N and TN when NO2 -Increase of the N concentration to 100 mg.L-1When is NO2 --N removal 68.93%; NO2 --N concentration of 200 mg.L-1While LJ2 can still grow, the NO2- -N removal rate still remains 9.06%,
bacillus coaguluns YX-6 as initial NO2 --N concentration of 20 mg.L-1When is NO2 -The removal rate of-N is close to 100 percent when NO2 -Increase of the N concentration to 100 mg.L-1,NO2 -the-N removal was only 20%. Therefore, LJ2 tolerates higher concentrations of NO than YX-62 --N. It is reported that when the concentration of nitrite nitrogen is 50 mg.L-1、100mg·L-1、200mg·L-1In the presence of nitrogen, Acinetobacter sp.Y1 can grow, and NO is present2 -The removal rate of-N can reach more than 60 percent, but Y1 can tolerate 14C/N which is far lower than the optimal C/N60 of LJ 2. Therefore, under the condition of high concentration of organic matters, LJ2 has good NO2 -the-N tolerance capability and denitrification effect are superior to most of aerobic denitrification strains reported at present.
The above description is only for the preferred embodiment of the present application and should not be taken as limiting the present application in any way, and although the present application has been disclosed in the preferred embodiment, it is not intended to limit the present application, and those skilled in the art should understand that they can make various changes and modifications within the technical scope of the present application without departing from the scope of the present application, and therefore all the changes and modifications can be made within the technical scope of the present application.