Analysis Of Bacterial Community Structure Research Articles

Effect of Cucumber Continuous Monocropping on Traditional Chinese Medicine Residue through Analysis of Physicochemical Characteristics and Microbial Diversity

The use of traditional Chinese medicine (TCM) residue as a crop culture substrate has unique advantages in alleviating the obstacles associated with continuous monocropping, such as increasing production, improving quality and alleviating pests and diseases. However, the effect of TCM residue application on substrates in continuous monocropping practices has not been determined. In this study, the cucumber variety “Jinyou No. 10” was used as the material, and fermented TCM residue, vermiculite and perlite were used as organic substrates (3:1:1). The cucumbers were cultivated on substrates for different durations of continuous monocropping, which were the first cropping cycle (A1), second cropping cycle (A2), third cropping cycle (A3) and fourth cropping cycle (A4). The control (A0) was the substrate sample without any crop planted in it. After the cucumbers were harvested, substrate samples (areas around the cucumber roots) were collected. The physiochemical properties of the cultivated substrates were determined, and the microbial community structures were analyzed through 16S rRNA and ITS sequencing. The physiochemical indices of the substrates with different durations of continuous monocropping (A1–A4) were significantly different than those of the control (A0) substrate. Moreover, the continuous cropping of cucumber had greater effects on fungal communities than on bacterial communities. Bacterial community structure analysis revealed a greater proportion of important bacterial taxa (Proteobacteria, Chloroflexi, and Nitrospirae) in the continuous monocropping substrates than in the A0 substrate. For the fungal community, Ascomycota accounted for the largest percentage of the fungal community in all the samples. The diversity of the microbial community was found to be influenced primarily by electrical conductivity, organic matter content, pH and total potassium content according to the correlation analysis of physicochemical properties and relative abundance of the microbial community. Our study would provide a basis for addressing persistent challenges in continuous cropping and for obtaining the utmost benefit from using TCM organic residue waste.

Bacterial community structure analysis of sludge from Taozi lake and isolation of an efficient 17β-Estradiol (E2) degrading strain Sphingobacterium sp. GEMB-CSS-01

Environmental challenges arising from organic pollutants pose a significant problem for modern societies. Efficient microbial resources for the degradation of these pollutants are highly valuable. In this study, the bacterial community structure of sludge samples from Taozi Lake (polluted by urban sewage) was studied using 16S rRNA sequencing. The bacterial phyla Proteobacteria, Bacteroidetes, and Chloroflexi, which are potentially important in organic matter degradation by previous studies, were identified as the predominant phyla in our samples, with relative abundances of 48.5%, 8.3%, and 6.6%, respectively. Additionally, the FAPROTAX and co-occurrence network analysis suggested that the core microbial populations in the samples may be closely associated with organic matter metabolism. Subsequently, sludge samples from Taozi Lake were subjected to enrichment cultivation to isolate organic pollutant-degrading microorganisms. The strain Sphingobacterium sp. GEMB-CSS-01, tolerant to sulfanilamide, was successfully isolated. Subsequent investigations demonstrated that Sphingobacterium sp. GEMB-CSS-01 efficiently degraded the endocrine-disrupting compound 17β-Estradiol (E2). It achieved degradation efficiencies of 80.0% and 53.5% for E2 concentrations of 10 mg/L and 20 mg/L, respectively, within 10 days. Notably, despite a reduction in degradation efficiency, Sphingobacterium sp. GEMB-CSS-01 retained its ability to degrade E2 even in the presence of sulfanilamide concentrations ranging from 50 to 200 mg/L. The findings of this research identify potential microbial resources for environmental bioremediation, and concurrently provide valuable information about the microbial community structure and patterns within Taozi Lake.

Diversity and spatiotemporal variations in bacterial and archaeal communities within Kuwaiti territorial waters of the Northwest Arabian Gulf.

Kuwaiti territorial waters of the northwest Arabian Gulf represent a unique aquatic ecosystem prone to various environmental and anthropogenic stressors that pose significant constraints on the resident biota which must withstand extreme temperatures, salinity levels, and reducing conditions, among other factors to survive. Such conditions create the ideal environment for investigations into novel functional genetic adaptations of resident organisms. Firstly, however, it is essential to identify said organisms and understand the dynamic nature of their existence. Thus, this study provides the first comprehensive analysis of bacterial and archaeal community structures in the unique waters of Kuwait located in the Northwest Arabian Gulf and analyzes their variations with respect to depth, season, and location, as well as their susceptibility to changes in abundance with respect to various physicochemical parameters. Importantly, this study is the first of its kind to utilize a shotgun metagenomics approach with sequencing performed at an average depth of 15 million paired end reads per sample, which allows for species-level community profiling and sets the framework for future functional genomic investigations. Results showed an approximately even abundance of both archaeal (42.9%) and bacterial (57.1%) communities, but significantly greater diversity among the bacterial population, which predominantly consisted of members of the Proteobacteria, Cyanobacteria, and Bacteroidetes phyla in decreasing order of abundance. Little to no significant variations as assessed by various metrics including alpha and beta diversity analyses were observed in the abundance of archaeal and bacterial populations with respect to depth down the water column. Furthermore, although variations in differential abundance of key genera were detected at each of the three sampling locations, measurements of species richness and evenness revealed negligible variation (ANOVA p<0.05) and only a moderately defined community structure (ANOSIM r2 = 0.243; p>0.001) between the various locations. Interestingly, abundance of archaeal community members showed a significant increase (log2 median ratio of RA = 2.6) while the bacterial population showed a significant decrease (log2 median ratio = -1.29) in the winter season. These findings were supported by alpha and beta diversity analyses as well (ANOSIM r2 = 0.253; p>0.01). Overall, this study provides the first in-depth analysis of both bacterial and archaeal community structures developed using a shotgun metagenomic approach in the waters of the Northwest Arabian Gulf thus providing a framework for future investigations of functional genetic adaptations developed by resident biota attempting to survive in the uniquely extreme conditions to which they are exposed.

Analysis of bacterial community structure and taste quality of different colored high-temperature Daqu in the Xiangyang region, China

In this study, the differences in bacterial community structure and taste quality among the three different colored high-temperature Daqu (HTD) produced by Enterprise-A were investigated. Furthermore, these HTD were compared to HTD produced by local Enterprise-B. The results revealed yellow HTD of Enterprise-A showed significantly higher bacterial richness and diversity (P < 0.05). The dominant bacterial genera were Bacillus (27.09%), Lentibacillus (21.28%), Kroppenstedtia (12.68%), Thermoactinomyces (8.83%). The electronic tongue detection showed that black HTD presented significantly higher taste attributes, such as sourness, astringency, and bitter aftertaste (P < 0.05). Highly significant positive correlations between Bacillus with umami and saltiness were observed (P < 0.01), while a highly significant negative correlation was found between Bacillus and sourness (P < 0.01). Furthermore, the PCoA and cluster analysis revealed that the three colored HTD samples from the same enterprise were closer to each other. Finally, 84 bacterial strains were isolated from the HTD of Enterprise-A using pure culture methods, including B. amyloliquefaciens, B. licheniformis, Caldibacillus hisashii, and Pediococcus acidilactici. This study provides a greater understanding of the quality of HTD from Enterprise-A and reveals that the production process employed by different enterprises has a greater impact on the microbial community structure of HTD, compared to the differences in temperature during fermentation.

Effects of Biogas Slurry Application on Soil Microbial Communities Structure and Function During Wheat-rice Stubble Period

To reveal the effects of biogas slurry application on soil microbial community structure and function, a soil column experiment was constructed with three treatments[(no N addition, CM; conventional fertilization, SN; biogas slurry addition, SZ)]. The differences in composition, diversity, and structure of bacterial and fungal communities on day 1 and day 21 after soil flooding were evaluated, and their functions were predicted using Illumina high-throughput sequencing technology. The results of the analysis of α diversity showed that the fungal α-diversity indexes of CM, SN, and SZ treatments on day 1 were significantly higher than those on day 21, and there was no significant difference among the three treatments. However, the bacterial Simpson index differed among the three treatments on day 21, with SZ-21 showing a higher Simpson index but lower Chao1 index compared with those of SZ-21. The analysis of bacterial community structure showed that Firmicutes, Chloroflexi, and Actinobacteria in the SN-1 treatment were different from those in the other treatments on day 1, whereas the relative abundance of bacterial phyla in the SZ and SN treatments were similar on day 21. The analysis of fungal community structure showed that the relative abundance of Ascomycota and Zygomycota in the SZ-1 treatment were higher than those in the SN-1 and CM-1 treatments on day 1. The relative abundance of Ascomycota in the SN-21 and SZ-21 treatments were lower, whereas that of Zygomycota were higher compared with that in CM-21. The analysis of NMDS showed that the composition of bacterial and fungal communities in the SN and SZ treatments showed a gradually similar trend. The PICRUSt analysis showed that the function of the soil bacterial community was similar in the CM, SN, and SZ treatments. The FUNGuild function prediction reflected that the main differences in trophic type between the SN-21 and SZ-21 treatments occurred in saprotroph and pathotroph forms. Therefore, biogas slurry addition in the wheat-rice stubble stage could contribute to balancing soil nutrients and maintaining soil ecological function to a certain extent, but there may still be a risk of fungal disease.

Analysis of Soil Bacterial Community Structure and Ecological Function Characteristics in Different Pollution Levels of Lead-zinc Tailings in Datong

A rapid rise in industrialization has led to the accumulation of copious mining waste, which has caused serious destruction of the ecological environment, resulting in severe pollution problems that need to be addressed urgently. In this study, altered soil bacterial communities in different polluted areas were analyzed using the Illumina high-throughput sequencing technique. The primary factors along with physical and chemical factors influencing the soil bacterial communities were also investigated, and the associated potential ecological functions were predicted. The results of these analyses indicated that aggravated pollution caused severe loss of tailing soil nutrients. A total of 14253 bacterial OTU was obtained from the soil samples. The total numbers of OTU in the heavily polluted area (W1), moderately polluted area (W2), lightly polluted area (W3), and clean area (CK) were 3240, 3330, 3813, and 3870, respectively. However, the soil OTUs decreased gradually with increasing pollution. In the α-diversity index analysis, the richness and evenness of the soil bacterial community were significantly decreased in the W1 group. A significant decrease in the Chao1, ACE, and Shannon indexes was also observed in the W1 group, whereas no significant difference was observed in the W3 group compared to the control. The dominant bacterial phyla identified in the soil wereβ-Actinobacteria, β-Proteobacteria, and β-Chloroflexi. Further, the relative abundance of β-Actinobacteria and β-Proteobacteria was high, whereas relative abundance of β-Chloroflexi in the W1-W3 groups was low compared to that in the control. The relative abundance of the dominant phylum in the W1 group was significantly different than that in the CK group (P<0.05). RDA showed that the soil physical and chemical properties selected in this study explained the total variation in soil bacterial community by 93.35%. Spearman analysis showed that β-Actinobacteria was negatively correlated with nitrogen source and organic matter and positively correlated with pH; β-Proteobacteria was negatively correlated with nitrogen source, phosphorus source, available potassium, and organic matter and positively correlated with total potassium and pH; and β-Chloroflexi was positively correlated with nitrogen source, phosphorus source, available potassium, and organic matter and negatively correlated with pH. Tax4 Fun was used to analyze the biological metabolic pathway. Heavy metal pollution in the soil affected the soil bacterial community and changed the main types of biological metabolism. The ecological functions of soil bacteria groups in different polluted areas were predicted by FAPROTAX. The results showed that the dominant metabolic patterns were affected by the pollution degree, and the metabolic patterns of soil bacteria in polluted areas were relatively single. The functional abundance of metabolic patterns of soil bacteria communities in CK was higher than that in polluted areas, which not only participated in degradation metabolism but also related to oxidation metabolism.

Evaluation of different 16S rRNA gene hypervariable regions and reference databases for profiling engineered microbiota structure and functional guilds in a swine wastewater treatment plant.

High-throughput 16S rRNA gene amplicon sequencing technology is widely applied for environmental microbiota structure analysis to derive knowledge that informs microbiome-based surveillance and oriented bioengineering. However, it remains elusive how the selection of 16S rRNA gene hypervariable regions and reference databases affects microbiota diversity and structure profiling. This study systematically evaluated the fitness of different frequently used reference databases (i.e. SILVA 138 SSU, GTDB bact120_r207, Greengenes 13_5 and MiDAS 4.8) and primers of 16S rRNA gene in microbiota profiling of anaerobic digestion and activated sludge collected from a full-scale swine wastewater treatment plant (WWTP). The comparative results showed that MiDAS 4.8 achieved the highest levels of taxonomic diversity and species-level assignment rate. For whichever sample groups, microbiota richness captured by different primers decreased in the following order: V4 > V4-V5 > V3-V4 > V6-V8/V1-V3. Using primer-bias-free metagenomic data results as the judging standard, V4 region also best characterized microbiota structure and well represented typical functional guilds (e.g. methanogens, ammonium oxidizers and denitrifiers), while V6-V8 regions largely overestimated the archaeal methanogens (mainly Methanosarcina) by over 30 times. Therefore, MiDAS 4.8 database and V4 region are recommended for best simultaneous analysis of bacterial and archaeal community diversity and structure of the examined swine WWTP.

Effects of the fungicide trifloxystrobin on the structure and function of soil bacterial community

Trifloxystrobin has been widely applied to prevent fungal diseases because of its high efficiency and desirable safety characteristics. In the present study, the effects of trifloxystrobin on soil microorganisms were integrally investigated. The results showed that trifloxystrobin inhibited urease activity, promoted dehydrogenase activity. Downregulated expressions of the nitrifying gene (amoA), denitrifying genes (nirK and nirS), and carbon fixation gene (cbbL) were also observed. Soil bacterial community structure analysis showed that trifloxystrobin changed the abundance of bacteria genera related to nitrogen and carbon cycle in soil. Through the comprehensive analysis of soil enzymes, functional gene abundance, and soil bacterial community structure, we concluded that trifloxystrobin inhibited both nitrification and denitrification of soil microorganisms, and also diminished the carbon-sequestration ability. Integrated biomarker response analysis showed that dehydrogenase and nifH were the most sensitive indicators of trifloxystrobin exposure. It provides new insights about trifloxystrobin environmental pollution and its influence on soil ecosystem.

Analysis of bacterial community structure of Fuzhuan tea with different processing techniques.

The composition and diversity of microbial communities are of considerable significance to the quality development of Camellia sinensis (Fuzhuan tea). In this study, we examined differences in the bacterial community structures of loose, lightly-pressed, hand-made, and machine-pressed Fuzhuan teas and raw dark tea. We observed notable differences in the bacterial communities of the five groups, where there were only 51 consensus sequences. ASV/OTU Venn diagram, Chao1, Ace, Simpson indices, and dilution curve analyses consistently revealed that machine-pressed tea exhibited the highest bacterial diversity. Taxonomically, Actinobacteria, Firmicutes, Proteobacteria, and Cyanobacteria were the dominant bacterial phyla in each group, whereas Corynebacterium, Methylobacterium, and Bifidobacterium were the dominant genera. Our findings revealed significant differences in the bacterial community structures of different Fuzhuan tea products derived from the same raw material, with bacterial diversity rising with increased product compaction.

Degradation of sulfonamide antibiotics in the rhizosphere of two dominant plants in Huixian karst wetland, Guangxi, China

Abstract In this work, Phragmites australis and Vallisneria natans were selected as the research objects and were cultured for 10 d under 0.10 μg L−1 sulfadiazine (SD) stress in a simulated surface flow wetland reactor. SD degradation was conducted at pH = 7 and 25 °C for 96 h. Each plant group conformed to the first-order kinetic model of degradation, and the degradation rate increased with time, reaching the maximum at 96 h. At 96 h, the degradation rate of P. australis communities was higher than that of V. natans. SD metabolites showed that the degradation pathways in the plant rhizosphere were mainly hydroxylation, aminolation, and S–N bond cleavage. In the analysis of rhizosphere bacterial community structure, the bacterial phyla that could degrade antibiotics accounted for a large proportion. Compared with before degradation, the dominant phylum and genus did not change after degradation (96 h), but their abundance changed to varying degrees, and new genera appeared in the P. australis group. This research provides a reference for the degradation of antibiotics in karst areas and new information on the mechanism of SA degradation in the plant rhizosphere.

Analysis of bacterial diversity and community structure in gastric juice of patients with advanced gastric cancer

BackgroundThe occurrence and development of gastric cancer are related to microorganisms, which can be used as potential biomarkers of gastric cancer.ObjectiveTo screen the microbiological markers of gastric cancer from the microorganisms of gastric juice.MethodsGastric juice samples were collected from 61 healthy people and 78 patients with gastric cancer (48 cases of early gastric cancer and 30 cases of advanced gastric cancer). The bacterial 16 S rRNA V1-V4 region of gastric juice samples was sequenced. The Shannon index, Simpson index, Ace index and Chao index were used to analyze the diversity of gastric juice samples. The RDP classifier Bayesian algorithm was used to analyze the community structure of 97% OTU representative sequences with similar levels. Linear discriminant analysis and ST-test were used to analyze the differences. Six machine learning algorithms, including the logistic regression algorithm, random forest algorithm, neural network algorithm, support vector machine algorithm, Catboost algorithm and gradient lifting tree algorithm, were used to construct risk prediction models for gastric cancer and advanced gastric cancer.ResultsThe microbiota diversity and the abundance of bacteria was different in the healthy group, early gastric cancer and advanced gastric cancer (P < 0.05). The top five abundant bacteria among the three groups were Streptococcus, Rhodococcus, Prevotella, Pseudomonas and Helicobacter. Bacterial flora such as Streptococcus, Rhodococcus and Ochrobactrum were significantly different between the healthy group and the gastric cancer group. The accuracy of the random forest prediction model is the highest (82.73% correct). The bacteria with the highest predictive value included Streptococcus, Lactobacillus and Ochrobactrum. The abundance of bacteria such as Fusobacterium, Capnocytophaga, Atopobium, Corynebacterium was high in the advanced gastric cancer group.ConclusionGastric juice bacteria can be used as potential biomarkers to predict the occurrence and development of gastric cancer.

Increase in Cd Tolerance through Seed-Borne Endophytic Fungus Epichloë gansuensis Affected Root Exudates and Rhizosphere Bacterial Community of Achnatherum inebrians.

Soil cadmium (Cd) pollution is a serious environmental problem imperiling food safety and human health. The endophyte Epichloë gansuensis can improve the tolerance of Achnatherum inebrians to Cd stress. However, it is still unknown whether and how the endophyte helps host plants build up a specific bacterial community when challenged by CdCl2. In this study, the responses of the structure and function of bacterial community and root exudates of E+ (E. gansuensis infected) and E- (E. gansuensis uninfected) plants to Cd stress were investigated. Analysis of bacterial community structure indicated that the rhizosphere bacterial community predominated over the root endosphere bacterial community in enhancing the resistance of CdCl2 in a host mediated by E. gansuensis. E+ plant strengthened the interspecific cooperation of rhizosphere bacterial species. Moreover, the analysis of root exudates demonstrated E. gansuensis and increased the contents of organic acids and amino acids under Cd stress, and most root exudates were significantly correlated with rhizosphere bacteria. These results suggested that E. gansuensis employed a specific strategy to recruit distinct rhizosphere bacterial species and relevant functions by affecting root exudates to improve the tolerance of the host to Cd stress. This study provides a firm foundation for the potential application of symbionts in improving phytostabilization efficiency.

Comparison of Bacterial and Fungal Community Structure and Potential Function Analysis of Yak Feces before and after Weaning.

Weaning is one of the most stressful periods in yak growth. However, the impact of weaning on microbial diversity, structure, and potential function of yak feces is not clear. In this study, 12 Xinjiang yaks aged 3, 4, 5, and 6 months old were selected to collect fresh feces before and after weaning. Through 16S rRNA and ITS high-throughput sequencing, the dynamic distribution and potential function of yak fecal, bacterial, and fungal communities in each month were revealed. The study found that the richness of fungi had a significant impact on weaning. At the phylum level, Firmicutes, Bacteroidetes, Ascomycota, and Basidiomycota, and at the genus level, 5-7N15, Oscillospira, Roseburia, Dorea, Preussia, Neoascochyta, Naganishia, and Sporormiella were enriched in yak feces of different months old. The abundance and proportion of bacteria Firmicutes, Bacteroidetes, 5-7N15, and fungi Mucoromyceta changed significantly before and after weaning. With the increase of months, Verrucomicrobia and Akkermansia have shown a downward trend. Through the prediction and analysis of fecal microbial function, it was found that at the level of primary pathways, weaning has a significant impact on cellular processes, environmental information processing, genetic information processing, metabolism, and organismal systems. At the level of secondary metabolic pathways, weaning has a significant impact on cell motility, signal transduction, folding, sorting and degradation, translation, amino acid metabolism, glycan biosynthesis and metabolism, metabolism of terpenoids and polyketides, and xenobiotics biodegradation and metabolism. In addition, by analyzing the differences in functional pathways and microbial composition between sample groups of different months, it was found that the differences in functional pathways were related to the abundance differences of some microorganisms. In general, the changes in the composition and structure of yak fecal microflora may reflect the adaptability of the intestinal microbiota.

Comparison of the disinfection efficacy between ferrate(VI) and chlorine in secondary effluent

Disinfection is essential for the microbial safety of reclaimed water. Traditional chlorine disinfection leads to secondary problems such as disinfection by-products and chlorine-resistant bacteria. Ferrate (Fe(VI)) is a novel green disinfectant. However, research on the disinfection characteristics of Fe(VI) remains insufficient. This study compared the disinfection efficacy between Fe(VI) and chlorine in secondary effluent, including the inactivation efficiency of coliforms and heterotrophic bacteria and the control effect on typical chlorine-resistant bacteria. The results showed that Fe(VI) was more effective than chlorine in inactivating Escherichia coli and total coliforms at low doses, whereas chlorine was more effective than Fe(VI) in inactivating heterotrophic bacteria. A severe trailing phenomenon was observed in Fe(VI) disinfection. Based on bacterial community structure analysis, Fe(VI) was also found to be capable of controlling the relative abundance of some chlorine-resistant bacteria such as Sphingomonas, Bacillus, Mycobacterium and Legionella except for Pseudomonas. The results of this study could have implications in evaluating Fe(VI) disinfection ability and optimizing Fe(VI) dosing for disinfection.

Mechanism of dielectric barrier discharge plasma technology to improve the quantity of short-chain fatty acids in anaerobic fermentation of waste active sludge.

The mechanism of improving the anaerobic fermentation performance of waste active sludge by using dielectric barrier discharge (DBD) plasma pretreatment technology was investigated. The maximum accumulation of short-chain fatty acids (SCFAs) was observed on the 7th day of anaerobic fermentation when the DBD power was 76.50 W, which was 1726.70 mg COD/L, 1.50 times of the control group. The ratio of acetic acid in DBD group was 9.30% higher than that in the control. Further mechanism research indicated that DBD pretreatment can destroy the structure of extracellular polymer substances and release organic substances such as protein and polysaccharide. The dissolved organic matter analysis indicated that the DBD technique could increase the release of biodegradable organics (eg., tyrosine proteins, soluble microbial by-products), thus accelerate the biotransformation of organic substance. Bacterial community structure analysis showed that the increase in the abundance of Firmicutes and Bacteroidetes and the decrease in the abundance of Proteobacteria in DBD group were beneficial to the accumulation of SCFAs. Besides, further archaeal analysis indicated that the decrease of Methanosaeta sp. and Methanosarcina sp. abundance in the DBD group facilitate acetic acid accumulation. This study demonstrated that the DBD technique can be used as an effective and potential pretreatment method to improve sludge anaerobic fermentation performance.

Contribution of hippocampal BDNF/CREB signaling pathway and gut microbiota to emotional behavior impairment induced by chronic unpredictable mild stress during pregnancy in rats offspring.

BackgroundNumerous studies have shown that exposure to prenatal maternal stress (PMS) is associated with various psychopathological outcomes of offspring. The accumulating evidence linking bacteria in the gut and neurons in the brain (the microbiota-gut-brain axis) has been aconsensus; however, there is a lack of research on the involvement mechanism of gut microbiota in the regulation of the BDNF/CREB signaling pathway in the hippocampus of prenatally stressed offspring.MethodsPregnant rats were subjected to chronic unpredictable mild stress (CUMS) to establish the prenatal maternal stress model. The body weight was measured and the behavioral changes were recorded. Offspring were tested to determine emotional state using sucrose preference test (SPT), open-field test (OFT) and suspended tail test (STT). Gut microbiota was evaluated by sequencing the microbial 16S rRNA V3–V4 region, and the interactive analysis of bacterial community structure and diversity was carried out. The expression of hippocampal BDNF, TrkB and CREB mRNA and proteins were respectively measured using RT-PCR and Western blotting.ResultsPrenatal maternal stress increased maternal plasma corticosterone levels, slowed maternal weight gain and caused depression-like behaviors (all P < 0.05). In offspring, prenatal maternal stress increased plasma corticosterone levels (P < 0.05) and emotional behavior changes (depression-like state) were observed (P < 0.05). The species abundance, diversity and composition of the offspring’s gut microbiota changed after the maternal stress during pregnancy (P < 0.05). Compared with the control group’s offspring, the species abundance of Lactobacillaceae was dropped, while the abundance of the Muribaculaceae species abundance was risen. Concurrent, changes in the hippocampal structure of the offspring and decreases in expression of BDNF/CREB signaling were noted (P < 0.05).ConclusionsPrenatal maternal stress leads to high corticosterone status and abnormal emotion behavior of offspring, which may be associated with the abnormal BDNF/CREB signaling in hippocampus of offspring caused by the change of gut microbiota composition.

Molecular Analysis of Soil Bacterial Community Structures for Environmental Risk Assessment with Varieties of Genetically Modified Soybean and Hot Pepper

With the advance in gene technology, genetically modified (GM) crops have increased in recent years. GM crops offer us various benefits. However, there are potential risks of GM crops for the environment. In this study, the impacts of transgenic plants on soil microbial community structures were assessed. Two varieties of soybean (Glycine max L.) and hot pepper (Capsicum annuum L.), which introduced the herbicide-resistant gene, bar, were used in this study. The effects of GM crops on soil microbial community structures were investigated using a cultural method, the denaturing gradient gel electrophoresis (DGGE) procedure, and 16S rRNA gene sequencing on the Illumina platform. Additionally, the persistence of transgenes was monitored using a quantitative real-time PCR procedure. The cultural method, DGGE analysis, and the amplicon-based community profile indicated that soil microbial communities were not significantly different between GM and non-GM lines. The level of the bar gene in GM soybean plots greatly increased when the crops were actively growing, but thereafter gradually decreased to the initial level. Meanwhile, the level of the bar gene in GM hot pepper plots repeatedly increased and decreased according to the flowering stages. These results indicated that soil microbial community structures were not significantly affected.

Effects of pyroxsulam on soil enzyme activity, nitrogen and carbon cycle-related gene expression, and bacterial community structure

Pyroxsulam is a new herbicide which is being widely used to prevent the growth of broad-leaved weeds in wheat fields because of its low quantity of application and high efficiency. However, its ecotoxic effects on soil microorganisms have yet to be clarified. In the present study, the effects of pyroxsulam on soil enzymes, nitrogen and carbon cycle functional genes, and bacterial community structure in the soil were investigated. The effect of pyroxsulam on urease and dehydrogenase activities was not obvious at the end of the experiment (56 d), but β-glucoside activity was consistently promoted. At the enzyme level, the effect of different concentrations of pyroxsulam on soil enzymes was within an acceptable range. Functional gene expression analysis indicated that the expression of the nitrogen-fixing gene (nifH), nitrifying gene (amoA), and carbon fixation gene (cbbL) was inhibited by three different doses of pyroxsulam, and the inhibition was most effective at 2.5 mg kg−1. Therefore, the 2.5 mg kg−1 pyroxsulam dose had adverse effects on functional genes, and application should be controlled. Combined with the results of soil bacterial community structure analysis, we concluded that pyroxsulam inhibited soil nitrogen fixation, nitrification, and carbon dioxide fixation and promoted soil denitrification. In addition, pyroxsulam increased the abundance of beneficial bacteria with the ability to inhibit the spread of soil diseases and degrade organic pollutants. According to the integrated biomarker response calculations, the green-like cbbL gene was the most sensitive indicator of pyroxsulam toxicity. A high concentration of pyroxsulam may have a negative impact on soil microorganisms in different aspects and dosage should therefore be carefully considered.

Changes in bacterial community structure and quality characteristics during fermentation of stinky variegated carp ( Aristichthys nobilis )

Bacterial metabolism greatly affects the quality and flavor of traditional, low-salt fermented fish. We assessed changes in the bacterial community structure and quality characteristics of “stinky” variegated carp (Aristichthys nobilis) during fermentation at 20°C. The total viable count (TVC), firmness, chewiness, tackiness, total volatile base nitrogen (TVB-N) and thiobarbituric acid-reactive substance (TBARS) levels, and relative peak area of volatile compounds significantly (p < .05) increased, while the pH, weight, and elasticity dramatically decreased, during fermentation. The total free amino acid (FAA) content decreased early during fermentation (from 0–2 d) and then significantly (p < .05) increased (from 3–5 d). The levels of flavorful AAs (aspartic acid, glutamate, phenylalanine, tyrosine, alanine, and glycine) increased markedly after 4 d of fermentation. Solid-phase microextraction-gas chromatography–mass spectrometry (SPME-GC–MS) revealed that the levels of ketones, ethers, and nitrogenous compounds increased significantly (p < .05) during fermentation. Illumina MiSeq sequencing identified Plesiomonas as the dominant bacterial genus during fermentation, followed by Aeromonas, Cetobacterium, Vibrio, and Hathewaya. These bacteria may contribute to the flavor and aroma of stinky variegated carp. The association between bacterial succession and the flavor and taste of stinky fish was also discussed. Practical applications Variegated carp could be processed to create stinky fish. In this study, bacterial community structure and quality characteristics analysis were assessed. FAAs and volatile compounds related to flavor and aroma were found. A potential starter culture that could improve the quality of stinky variegated carp was identified. Our findings provide a theoretical basis for the industrial production of fermented stinky fish.

Peanut and cotton intercropping increases productivity and economic returns through regulating plant nutrient accumulation and soil microbial communities

BackgroundIntercropping (IC) has been widely adopted by farmers for enhancing crop productivity and economic returns; however, the underpinning mechanisms from the perspective of below-ground interspecific interactions are only partly understood especially when intercropping practices under saline soil conditions. By using permeable (100 μm) and impermeable (solid) root barriers in a multi-site field experiment, we aimed to study the impact of root-root interactions on nutrient accumulation, soil microbial communities, crop yield, and economic returns in a peanut/cotton IC system under non-saline, secondary-saline, and coastal saline soil conditions of China.ResultsThe results indicate that IC decreased the peanut pods yield by 14.00, 10.01, and 16.52% while increased the seed cotton yield by 61.99, 66.00, and 58.51%, respectively in three experimental positions, and consequently enhanced the economic returns by compared with monoculture of peanut (MP) and cotton (MC). The higher accumulations of nutrients such as nitrogen (N), phosphorus (P), and potassium (K) were also observed in IC not only in the soil but also in vegetative tissues and reproductive organs of peanut. Bacterial community structure analysis under normal growth conditions reveals that IC dramatically altered the soil bacterial abundance composition in both peanut and cotton strips of the top soil whereas the bacterial diversity was barely affected compared with MP and MC. At blossom-needling stage, the metabolic functional features of the bacterial communities such as fatty acid biosynthesis, lipoic acid metabolism, peptidoglycan biosynthesis, and biosynthesis of ansamycins were significantly enriched in MP compared with other treatments. Conversely, these metabolic functional features were dramatically depleted in MP while significantly enriched in IC at podding stage. Permeable root barrier treatments (NC-P and NC-C) counteracted the benefits of IC and the side effects were more pronounced in impermeable treatments (SC-P and SC-C).ConclusionPeanut/cotton intercropping increases crop yield as well as economic returns under non-saline, secondary-saline, and coastal saline soil conditions probably by modulating the soil bacterial abundance composition and accelerating plant nutrients accumulation.