Search Results (1,491)

Reasonably using reclaimed water (RW) for irrigation can help to alleviate water scarcity, while also providing both environmental and economic benefits. However, there is limited information regarding the potential impact of RW irrigation on the nutrients of saline–alkali soils and their microbial communities. This study investigates the effects of RW irrigation on saline–alkali soil properties and microbial communities using a 16S rRNA sequence analysis. The results show that the pH and electrical conductivity (EC) are significantly lower in RW treatment (p < 0.05). Compared to the saline–alkali soil that was not irrigated with RW (CK), the EC value decreased by 42.15–45.76%, in both 0–20 cm and 40–60 cm depth. RW exhibited a significant increase in the abundance of Actinobacteria (32.32–33.42%), Chloroflexi (7.63–15.79%), Firmicutes (9.27–10.42%), and Ascomycota (89.85–95.95%). Bacterial richness and diversity were significantly enhanced after RW irrigation (p < 0.05). At the genus level, the dominant bacterial genera included Bacillus, Penicillium, Aspergillus, and Talaromyces. Differences in the microbial community were observed between the two treatments and among soil depths within each treatment (p < 0.05). A network analysis indicated that the internal relationships among bacterial communities become more complex following RW irrigation, whereas the internal connections within fungal communities tend to become more simplified. A redundancy analysis (RDA) showed that soil microbial communities were directly influenced by EC, total nitrogen (TN), and available potassium (AK). Partial least squares path modeling (PLS-PM) results indicated that soil salinity and available nutrients were the most significant factors influencing the microbial community structure. Together, these results indicate that RW irrigation has a positive impact on ameliorating soil salinity and enhancing microbial community diversity in saline–alkali soils. These findings provide valuable insights for the future agricultural utilization of saline–alkali land. Full article

Organisms from the genus Streptomyces feature actinobacteria with complex developmental cycles and a great ability to produce a variety of natural products. These soil bacteria produce more than 2/3 of antibiotics used in medicine, and a large variety of bioactive compounds for industrial, medical and agricultural use. Although Streptomyces spp. have been studied for decades, the engineering of these bacteria remains challenging, and the available genetic tools are rather limited. Furthermore, most biosynthetic gene clusters in these bacteria are silent and require strategies to activate them and exploit their production potential. In order to explore, understand and manipulate the capabilities of Streptomyces spp. as a key bacterial for biotechnology, synthetic biology strategies emerged as a valuable component of Streptomyces research. Recent advancements in strategies for genetic manipulation of Streptomyces involving proposals of a large variety of synthetic components for the genetic toolbox, as well as new approaches for genome mining, assembly of genetic constructs and their delivery into the cell, allowed facilitation of the turnaround time of strain engineering and efficient production of new natural products at an industrial scale, but still have strain- and design-dependent limitations. A new perspective offered recently by technical advances in DNA sequencing, analysis and editing proposed strategies to overcome strain- and construct-specific difficulties in the engineering of Streptomyces. In this review, challenges and recent developments of approaches for Streptomyces engineering are discussed, an overview of novel synthetic biology strategies is provided and examples of successful application of new technologies in molecular genetic engineering of Streptomyces are highlighted. Full article

Increasing nitrogen (N) addition induces soil nutrient imbalances and is recognized as a major regulator of soil microbial communities. However, how soil bacterial abundance, diversity, and community composition respond to exogenous N addition in nutrient-poor and generally N-limited regions remains understudied. In this study, we investigated the effects of short-term exogenous N additions on soil bacterial communities using quantitative polymerase chain reaction (PCR) and Illumina Miseq sequencing in an in situ N addition field experiment. The results showed that a low nitrogen addition increased the observed species (Sobs) of the bacterial community, and with the increased nitrogen addition, the Sobs of bacteria gradually decreased, especially the unique OTUs. The relative abundance of Proteobacteria, Actinobacteria, and Gemmatimonadetes increased with increasing nitrogen addition, whereas the relative abundance of Chloroflexi and Firmicutes decreased. Soil properties play an important role in bacterial community structure at phylum or genus levels. Short-term nitrogen addition increased the proportion of nodes from Actinobacteria and Proteobacteria in the co-occurrence network and enhanced the stability of the microbial network. Actinobacteria may play an important role in constructing the network. Our study aims to explore the effects of nitrogen addition on the diversity, composition, and structure of soil bacterial communities in nutrient-poor areas caused by ecological disturbances. Full article

Urban landscape lakes are increasingly at risk of nitrogen-induced eutrophication. Microbial nitrogen transformation plays a crucial role in reducing nitrogen levels in these lakes. However, the relationships between microbial communities, nitrogen functional genes, and nitrogen dynamics in water and sediment, along with their underlying mechanisms, remain unclear. In this study, we systemically investigated the spatial distributions of physicochemical indicators in the overlying water and sediment in a typical urban landscape lake, Zizhuyuan Park, and the microbial communities and nitrogen cycling genes in the surface sediments of the lake connection (CO), side (SI), and center (CE) were evaluated via macrogenetic sequencing technology to analyze their relationships with environmental factors. The results revealed that the concentrations of TN, NO₃⁻, and NH₄⁺ in the lake water were within the ranges of 1.36~2.84, 0.98~1.92, and 0.01~0.29 mg·L⁻¹, respectively. The concentrations of TN, NO₃⁻, and NH₄⁺ in the sediments ranged from 1.17~3.47 g·kg⁻¹, 0.88~1.94 mg·kg⁻¹, and 5.61~10.09 mg·kg⁻¹, respectively. The contents of NH₄⁺ in water, TN and NO₃⁻ in sediments were significantly different in spatial distribution (p < 0.05). At the CE site, the Shannon diversity index was the highest and differed significantly from the values at the SI and CO sites (p < 0.01).The sediments of Central Lake contained a total of 36 phyla and 1303 genera of microorganisms. Proteobacteria (62.88–64.83%) and Actinobacteria (24.84–26.62%) accounted for more than 85% of the microorganisms. Nitrospirae, Ignavibacteriae, and Bacteroidetes were significantly different (p < 0.05) at the CE, and Planctomycetes were significantly different (p < 0.05) at the CO. The functional gene nrfA exhibited the highest abundance, followed by napA, nosZ, nirS, hao, ureC, norB, nifH, nirK, hdhA, nifB, and amoA. The abundances of hao and nifH differed significantly at various locations in Central Lake (p < 0.05). The key nitrogen transformation processes in the sediments, ranked by contribution rate, were DNRA, denitrification, nitrification, ammoniation, nitrogen fixation, and anammox. The six nitrogen processes showed significant differences (p < 0.01) in spatial distribution. The pH, TN, NO₃⁻, NH₄⁺, C/N ratio of the sediment, and NH₄⁺ in the lake water impact the microbial community and nitrogen conversion process. The sediment should be cleaned regularly, and the water cycle should be strengthened in urban landscape lakes to regulate microorganisms and genes and ultimately reduce nitrogen and control eutrophic water. This study can provide a reference for improving and managing lake water environments in urban landscapes. Full article

Background: The physical activity of different groups of individuals results in the rearrangement of microbiota composition toward a symbiotic microbiota profile. This applies to both healthy and diseased individuals. Multiple myeloma (MM), one of the more common hematological malignancies, predominantly affects older adults. Identifying an appropriate form of physical activity for this patient group remains a challenge. The aim of this study was to investigate the impact of a 6-week Nordic walking (NW) training program combined with a 10/14 time-restricted eating regimen on the gut microbiota composition of multiple myeloma patients. Methods: This study included healthy individuals as the control group (n = 16; mean age: 62.19 ± 5.4) and patients with multiple myeloma in remission (MM group; n = 16; mean age: 65.00 ± 5.13; mean disease duration: 57 months). The training intervention was applied to the patient group and consisted of three moderate-intensity sessions per week, individually tailored to the estimated physical capacity of each participant. The taxonomic composition was determined via 16S rRNA sequencing (V3–V9 regions). The microbiota composition was compared between the patient group and the control group. Results: The alpha and beta diversity metrics for species and genus levels differed significantly between the control and patient groups before the implementation of the NW program. In contrast, no differences were observed between the control and patient groups after the training cycle, indicating that the patients’ microbiota changed toward the pattern of the control group. This is confirmed by the lowest values of average dissimilarity between the MMB groups and the control at all taxonomic levels, as well as the highest one between the control group and the MMA patient group. The gut microbiota of the patients was predominantly represented by the phyla Firmicutes, Actinobacteria, Verrucomicrobia, Proteobacteria, and Bacteroidetes. Conclusions: The training, combined with time-restricted eating, stimulated an increase in the biodiversity and taxonomic rearrangement of the gut microbiota species. Full article

Wild fish are often considered more nutritionally valuable than cultured fish. This study aimed to elucidate the relationship between the gut microbiota and meat quality through the gut–muscle axis. Therefore, cultured and wild bighead carp (Hypophthalmichthys nobilis, Richardson 1845) from the Yangtze River were investigated to compare the differences in the meat quality and gut microbiota composition. Cultured bighead carp were collected from four intensive ponds along the Yangtze River area, while wild bighead carp were obtained from three different sites in the Yangtze River. The results showed that wild bighead carp muscle had significantly higher total saturated fatty acid (∑SFA) and total ω − 3 polyunsaturated fatty acid (∑n − 3 PUFA) content and water-holding capacity and lower lipid, histidine, and total ω − 6 polyunsaturated fatty acid (∑n − 6 PUFA) content than cultured bighead carp, while the muscle texture was not significantly different between the two groups, with the exception of the resilience. Moreover, the hindgut microbiota was analyzed using 16S rRNA high-throughput sequencing. The alpha and beta diversity differences between the cultured and wild groups were significant. The LEfSe analysis revealed Mycobacterium, Longivirga, and Acetobacteroides as biomarkers in cultured bighead carp, while Clostridium_T and other Firmicutes-associated genera were predominant in wild bighead carp. Regarding the relationship between the hindgut microbiota and meat quality, Mycobacterium exhibited a positive correlation with the muscle n-6 PUFA content and a negative correlation with muscle n − 3 PUFAs, while Clostridium_T exhibited the opposite pattern. According to the ecological network, the abundance of Actinobacteria could serve as a significant indicator of variations in the abundance of Mycobacterium and Clostridium_T. Consequently, differences in meat quality, particularly in the fatty acid composition, were observed between wild and cultured bighead carp. These differences may be associated with variations in the hindgut microbiota, shedding light on the gut–muscle axis. Full article

The current study investigates the systemic effects of imidacloprid, one of the most widely used neonicotinoid insecticides, on the liver and gut microbiome of rats in detail. With consideration of recent discussions on the potential harmfulness of imidacloprid to environmental and human health, the aim was to investigate the influence of this compound in the framework of controlled exposure at different dosages, namely, IMI-5, IMI-10, and IMI-30. Histopathological examination showed that liver morphology changed significantly with the dose, including in terms of cellular disorganization and signs of stress, with an alteration in the hepatic architecture. Morphological changes were related to disturbances in the activity of liver enzymes, reflecting deteriorating liver function with increased imidacloprid exposure. In parallel with this, a deep analysis of the gut microbiome revealed dramatic changes in microbial diversity and composition. Alpha diversity, represented by the Chao1 and Shannon indices, was significantly reduced with an increased dosage of imidacloprid. Subsequent beta diversity analysis, as visualized by principal component analysis, showed distinct clustering among the microbial communities, separated well between control and imidacloprid-treated groups, especially at higher dosages. Taxonomic analysis revealed an increase in the Firmicutes/Bacteroidetes ratio and a change in key phyla including Actinobacteria, Bacteroidetes, and Verrucomicrobia. A heatmap and bar charts further confirmed dose-dependent changes in microbial abundance. These changes point toward imidacloprid-induced dysbiosis, a reduction in microbial diversity, and an imbalance in the F/B ratio, usually associated with metabolic disorders. Overall, given these findings, it would seem that imidacloprid does indeed impose serious negative impacts on both liver function and gut microbiota composition and may have further impacts on health and ecological safety. Full article

Actinobacteria are well known for their production of metabolites of interest. They have been previously studied to identify new antibiotics in medical research and for their ability to stimulate plant growth in agronomic research. Actinobacteria represents a real source of potential biocontrol agents (BCAs) today. With the aim of reducing the use of phytosanitary products by 50% with the different Ecophyto plans, a possible application is the fight against mycotoxin-producing fungi in food matrices and crops using BCAs. To deal with this problem, the use of actinobacteria, notably belonging to the Streptomyces genus, or their specialized metabolites seems to be a solution. In this review, we focused on the impact of actinobacteria or their metabolites on the development of mycotoxigenic fungi and mycotoxin production on the one hand, and on the other hand on their ability to detoxify food matrices contaminated by mycotoxins. Full article

The aim of this study was to investigate the effects of terpinen-4-ol (TER) supplementation on the intestinal barrier function of pigs. Five groups of fifty 28-day-old piglets with comparable body weights were randomly assigned to the following groups: the control group (CON), the lipopolysaccharide group (LPS), the low TER group (PLT), the middle TER group (PMT), and the high TER group (PHT). The basal diet was given to the CON and LPS groups, and 30, 60, or 90 mg/kg TER was added to the basal diet for the TER groups. After the 21-day trial period, piglets in the LPS and TER groups received an intraperitoneal injection of 100 μg/kg body weight of LPS, whereas the piglets in the CON group received an injection of 0.9% normal saline solution. The results showed that LPS stimulation resulted in a decrease (p < 0.05) in the depth of colonic crypts in piglets, which was greater (p < 0.05) in the TER group. Compared with those in the CON group, the number of goblet cells and MUC2 expression were decreased in the colon of piglets in the LPS group, while these parameters were increased in the PMT group (p < 0.05). The malondialdehyde (MDA) content was greater in the colon of the LPS group than in that of the CON group, while the activities of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), and catalase (CAT) were lower in the colon of the LPS group; conversely, the MDA content was lower in the colons of the PLT and PMT groups than in those of the LPS group (p < 0.05). TER also reduced (p < 0.05) LPS-induced upregulation of IL-1β and TNF-α expression, along with the relative gene expression of NLRP3, ASC, and caspase-1 in the colon of piglets (p < 0.05). Compared with those in the CON group, the abundances of Firmicutes and UCG-005 in the LPS group were lower (p < 0.05), and those in the TER group were significantly greater than those in the LPS group. Compared with those in the CON group, the abundance of Proteobacteria in the LPS group increased (p < 0.05), while the abundance of Actinobacteria and Phascolarctobacterium increased (p < 0.05) in the colon of the PHT group compared with that in the LPS group. In conclusion, TER effectively improved the intestinal barrier function of the colon in weaning piglets. Based on the results of this study, the appropriate dose of TER in the diets of weaning piglets was 60 mg/kg. Full article

This study investigated the fatty acids (FA) profile of 54 actinomycete strains isolated from marine sediments collected off the Portugal continental coast, specifically from the Estremadura Spur pockmarks field, by GC/MS. Fatty acid methyl esters (FAMEs) were prepared from the ethyl acetate lipidic extracts of these strains and analyzed by gas chromatography–mass spectrometry (GC/MS), with FA identification performed using the NIST library. The identified FAs varied from C12:0 to C20:0, where 32 distinct FAs were identified, including 7 branched-chain fatty acids (BCFAs), 9 odd-chain fatty acids (OCFAs), 8 monounsaturated fatty acids (MUFAs), 6 saturated fatty acids (SFAs), 1 polyunsaturated fatty acid (PUFA), and 1 cyclic chain fatty acid (CCFA). The average expressed content was BCFA (47.54%), MUFA (28.49%), OCFA (26.93%), and SFA (22.16%), of which i-C16:0, C18:1ω9, and C16:0 were predominant, while PUFA (3.58%) and CCFA (0.41%) were identified as minor components. The identified BCFA were i-C16:0, a-C15:0, i-C15:0, i-C15:1ω6, a-C16:0, a-C14:0, and i-C17:0, which include combined branching and unsaturation and branching and odd. SFAs were present in all species, with C16:0 and C18:0 being the most representative. Rare OCFAs C19:1ω9, C17:1ω7, C15:0, and C17:0 were expressed. PUFA C18:1ω9 was detected; within this class, omega families ω9, ω7, ω6, and ω5 were identified, and no ω3 was detected. The only CCFA was benzene-butanoic acid (benzene-C4:0). These findings highlight the metabolic versatility of actinomycetes, providing valuable insights into microbial chemotaxonomy and offering promising biochemical leads for the development of biofuel, nutraceutical, and antifungal agents. Furthermore, these results underline the diversity and biotechnological potential of FAs in actinomycetes, uncovering their potential to be used as microbial cell factories, and paving the way for innovations in biofuels, pharmaceuticals, and eco-friendly industrial products. Full article

This study focused on Stichopus monotuberculatus and conducted stress experiments at salinity levels of 20‰ and 40‰. Intestinal histological changes and the structural characteristics of the intestinal flora of S. monotuberculatus under salinity stress were analyzed. The results show that acute salinity stress inflicts varying degrees of damage to the intestinal tissues of S. monotuberculatus. Salinity stress enhances the species diversity of intestinal flora in S. monotuberculatus. Eight phyla of bacteria are detected in the intestine of S. monotuberculatus. Dominant phyla include Proteobacteria, Firmicutes, and Actinobacteria. Furthermore, functional prediction reveals that acute salinity stress can significantly modify the abundance of pathways associated with nutrient and energy metabolism mediated by the intestinal flora of S. monotuberculatus. These results indicate that acute salinity stress induces pathological damage to the intestinal tissues of S. monotuberculatus, compromising the microbial habitat and leading to alterations in the intestinal flora composition. Additionally, S. monotuberculatus can mitigate salinity stress by adjusting the composition of its intestinal flora and the corresponding functional pathways. Full article

Daunorubicin (DNR) is an anthracycline antibiotic originating from soil-dwelling actinobacteria extensively used to treat malignant tumors. Over the decades, extensive attempts were made to enhance the production of anthracyclines by introducing genetic modifications and mutations in combination with media optimization, but the target production levels remain comparatively low. Developing an appropriate culture medium to maximize the yield of DNR and preventing autotoxicity for the producing organism remains a challenge. Our prospective review sheds light on a method involving perturbation that enhances the precursors to regulate the type II PKS pathway, enhancing cells’ capacity to increase secondary metabolite production. The suggested method also entails the preparation of culture media for the cultivation of Streptomyces sp. and enhanced yield of DNR, as well as making it inactive with iron or its reduced forms following efflux from the producer. The iron or iron–DNR complex is encapsulated by oleic acid or lipid micelle layers in the culture media, finally resulting in the generated inactive DNR and the DNR–iron–oil complex. This idea has the potential to protect the producer organism from autotoxicity and prevent the inhibition of metabolite production. The approach of substituting sugar with oil in culture media has a dual role wherein it promotes Streptomyces growth by utilizing lipids as an energy source and encapsulating the generated DNR–iron complex in the medium. In this review, we discussed aspects like anthracycline producers, biosynthesis pathways, and gene regulation; side effects of DNR; mechanisms for autotoxicity evasion; and culture media components for the enhancement of DNR production in Streptomyces sp. We anticipate that our work will help researchers working with secondary metabolites production and decipher a methodology that would enhance DNR yield and facilitate the extraction of the resulting DNR by lowering costs in large-scale fermentation. Full article

In our large-scale search for antimicrobial-producing bacteria, we isolated an actinomycete strain from rhizospheric soil of Bambusa vulgaris. The strain designated BP-8 showed noticeable antibacterial activity. BP-8 was subjected to a whole-genome analysis via a polyphasic taxonomy approach, and its antibacterial metabolite was identified by HRLS-MS. The results of the physiological and morphological analyses indicated that BP-8 is an aerobic, neutrophilic, mesophilic organism that is tolerant to 8% NaCl and can use a wide range of carbohydrates. It forms curly sporophores with a warty surface. The results of the phylogenetic and average nucleotide identity analyses and in silico DNA–DNA hybridization calculation indicated that BP-8 represents the type strain of a novel Streptomyces species. A comparative in silico analysis of the genome sequences of BP-8 and its closest related strains revealed the presence of genes encoding chemotaxonomic markers characteristic of Streptomyces. The antibacterial compound was identified as amicetin. Genomic mining also revealed more than 10 biosynthetic gene clusters that have not been described previously and may lead to the discovery of new valuable compounds. On the basis of these results, strain BP-8^T (=VKM Ac-3066^T = CCTCC AA 2024094^T) is proposed as the type strain of the novel species Streptomyces sirii sp. nov. Full article

To evaluate the effects of the type and proportion of bulking agents on compost maturity, chicken manure feedstock (J) was selected as the main raw material for aerobic composting, and wood chips (M), straw (S), and cornmeal (Y) were used as bulking agents. The ratios of chicken manure feedstock to the three bulking agents were set at 1:3, 1:1, and 3:1, respectively. The compost mixture composed of wood chips (M) and feedstock (J) in a 1:1 ratio exhibited the highest temperature (75 °C). The treatment with a bulking-agent-to-feedstock ratio of 3:1 exhibited the lowest temperature (52 °C) and the longest high-temperature period (about 10 days). Moreover, the compost mixture composed of wood chips (M) and feedstock (J) in a 3:1 ratio exhibited the highest seed germination index (1.32), while the GI values for all cornmeal treatments did not meet the standard requirements (0.4). The predominant microorganisms in all three treatments included Firmicutes, Bacteroidetes, Actinobacteria, and Proteobacteria. The total carbon transformation-related microorganism abundance in MJ31, SJ31, and YJ31 was 1.65%, 10.69%, and 3%, respectively. Further analysis showed that the bioavailability of feedstock was strongly correlated with compost maturity. The treatment with a bulking-agent-to-feedstock ratio of 3:1, with the highest GI, also exhibited the highest bioavailability. These results can guide the selection of the appropriate bulking agent and the optimal bulking-agent-to-feedstock ratio, offering a new direction for the optimization of the composting process. Full article

Biological soil crusts are integral to Arctic ecosystems, playing a crucial role in primary production, nitrogen fixation and nutrient cycling, as well as maintaining soil stability. However, the composition and complex relationships between the diverse organisms within these biocrusts are not well studied. This study investigates how the microbial community composition within Arctic biocrusts is influenced by environmental factors along an altitudinal gradient (101 m to 314 m). Metagenomic analyses were used to provide insights into the community composition, revealing that temperature, pH, and nutrient availability significantly shaped the community. In contrast, altitude did not directly influence the microbial composition significantly. Eukaryotic communities were dominated by Chloroplastida and fungi, while Proteobacteria and Actinobacteria prevailed among prokaryotes. Cyanobacteria, particularly orders such as Pseudoanabaenales, Pleurocapsales, and Nostocales, emerged as the most abundant photoautotrophic organisms. Our findings highlight the impact of environmental gradients on microbial diversity and the functional dynamics of biocrusts, emphasizing their critical role in Arctic tundra ecosystems. Arctic biocrusts are intricate micro-ecosystems, whose structure is strongly shaped by local physicochemical parameters, likely affecting essential ecological functions. Full article