Hongsheng Liu , Huawei Feng , Li Zhang , Jinhui Meng , Xue Dong
2020, 60(5):841-855. DOI: 10.13343/j.cnki.wsxb.20190403 CSTR: 32112.14.j.AMS.20190403
Abstract:Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is a novel high-throughput technology widely used in rapid identification of clinical microorganisms, food microorganisms and aquatic microorganisms. Currently, however, how to further improve the resolution of MALDI-TOF MS in microbial identification is a major challenge for this technology. To effectively deal with the large amounts of high-dimensional microbial MALDI-TOF MS data, a variety of machine learning algorithms have been applied. This paper reviews the applications of machine learning in MALDI-TOF MS identification of microorganisms. Herein, the workflow of machine learning in the classification of microbial MALDI-TOF MS is introduced. Then, the characteristics of MALDI-TOF MS data, MALDI-TOF MS database, the preprocessing of the MALDI-TOF MS data, and the performance evaluation of the model are further described. The applications of typical machine learning classification algorithms and ensemble learning algorithms are also discussed.
Xinyan Dong , Xue Liu , Manni Liu , Xiangling Zhang , Guoqing Wang
2020, 60(5):856-863. DOI: 10.13343/j.cnki.wsxb.20190420 CSTR: 32112.14.j.AMS.20190420
Abstract:Gut microbiota plays a significant role in the balance between health and disease. Akkermansia muciniphila is one of the intestinal bacteria and its specialization in mucin degradation makes it a key organism at the mucosal interface between the lumen and host cells. A. muciniphila is found inversely associated with obesity, diabetes, cardiometabolic diseases and low-grade inflammation. Oral administration of A. muciniphila reduces the symptoms of metabolic disease in mice. Therefore, A. muciniphila is a promising candidate for the treatment of diabetes and obesity. Here, we summarize the existing data on A. muciniphila and its role in diabetes and obesity, to provide insight into the intricate mechanisms of A. muciniphila regulation of the cross-talk between the host and gut microbiota, so as to provide ideas for further research on A. muciniphila bacteria and the development of new drugs for diabetes.
Tao Peng , Siyi Zhang , Luting Wang , Zhenzhen He , Longfei Shu
2020, 60(5):864-874. DOI: 10.13343/j.cnki.wsxb.20190454 CSTR: 32112.14.j.AMS.20190454
Abstract:Amoebas are important components of terrestrial ecosystems, and play a key role in soil nutrient cycling and energy flow. Amoebas have complex relationships with bacteria. On one hand, amoebas can directly affect the bacterial community and diversity through predation and enhance bacterial activity. On the other hand, bacteria have also evolved mechanisms to resist predation and even to infect amoebas, thus adversely affecting the growth and diversity of amoebas. In recent years, the interactions between amoebas and bacteria have attracted much attention. This paper summarizes the evolutionary history of amoebas-bacteria interactions, ecological relationships (predation, commensalism, parasitism, and mutualism) and their potential impacts on the environment. This review will improve our understanding about this research field and provide new ideas for the study of other protists-bacteria interactions, as well as exploring the mechanism of host-bacteria interactions in general.
Xiaona An , Weicheng Li , Jie Yu , Lin Pan , Lanxin Mo , Caiqing Yao , Heping Zhang
2020, 60(5):875-886. DOI: 10.13343/j.cnki.wsxb.20190345 CSTR: 32112.14.j.AMS.20190345
Abstract:[Objective] We studied the genetic diversity and habitat adaptability mechanism of 34 strains of Lactobacillus reuteri from different sources. We aimed to compared the differences of their adaptability in extraintestinal and intraintestinal habitats to provide theoretical basis for the development of Lactobacillus reuteri strains. [Methods] Based on the second generation sequencing platform, We sequenced 11 Lactobacillus reuteri strains from fermented food (yogurt and sour porridge) and compared with the genomes of fermented food, sour dough and herbivore sources of Lactobacillus reuteri strains by comparative genomics. [Results] The average genome size and GC content of L. reuteri isolated from yoghurt and sour porridge were 2.14 Mb and 38.77% respectively, and the phylogenetic relationship between the isolates from the same source was close. Pan-core gene sets consisted of 7242 and 969 gene families, yoghurt isolates had the most specific genes (459). Functional annotation showed that the number and types of carbohydrate and amino acid related genes varied greatly among strains from different sources, and the antibiotic resistance genes were found only in fermented food and herbivores strains. The carbohydrate-active enzymes of GH3 (β-glucosidase etc.) and GH43 (β-xylosidase etc.)only appeared in fermented food herbivore isolates, and the specific ones were AA3 (cellobiose dehydrogenase etc.) and GH66 (dextranase etc.), respectively. [Conclusion] Lactobacillus reuteri from different sources has a wide range of genetic diversity and is closely related to the living environment. Fermented food isolates had the characteristics of some herbivorous intestinal strains and their unique environmental adaptability, and reflected the host environmental adaptability. It can deepen the understanding of food fermentation and bacterial habitat adaptability in intestinal environment.
Peng Xu , Dahong Wang , Yingying Zheng , Wenhao Shen
2020, 60(5):887-896. DOI: 10.13343/j.cnki.wsxb.20190349 CSTR: 32112.14.j.AMS.20190349
Abstract:[Objective] The aim of this study was to isolate and identify ε-polylysine-producing (ε-PL) actinomycetes from the environment, followed by determining the structure of ε-PL, and studying its inhibition of microbial growth. [Methods] Strains were isolated based on the transparent zone formed by themethylene blue and ε-PL. Itzhaki method was used to screen the strains. A bacterium strain was identified by morphological and physiological characterization and sequence analyses of 16S rRNA and gyrB gene. The structure of ε-PL was studied by spectrum analysis. Its antimicrobial activity was measured by inhibition zone method. [Results] We isolated 3 actinomycete strains. Strain X-18, with the highest ε-PL yield (0.8 g/L), was identified as Streptomyces albulus. The molecular polymerization degree of ε-PL was 25-30 by the spectral data analysis and the comparison with the ε-PL standard. Its antimicrobial effect was better on bacteria than fungi. [Conclusion] An ε-PL-producing strain S. albulus X-18 was successfully isolated to enrich the resources of ε-PL producers.
Dongjin Leng , Xiaojing Hu , Xing Li , Yixin Ou , Qianjin Kang , Linquan Bai , Zixin Deng
2020, 60(5):897-911. DOI: 10.13343/j.cnki.wsxb.20190352 CSTR: 32112.14.j.AMS.20190352
Abstract:[Objective] To obtain targeted natural products and the bacterial producers based on characteristic biosynthesis genes and transcription level analysis. [Methods] First, we directionally mined the secondary metabolites producers by 5 pair of degenerate primers according to the conserved biosynthesis genes. Then RT-qPCR guided fermentation medium optimization was performed. Finally, the targeted natural products were isolated using different chromatography technologies, and their chemical structures were identified based on High Resolution Mass Spectrometry (HRMS) and Nuclear Magnetic Resonance (NMR).[Results] The AHBA synthase and epoxidase-encoding genes positive Streptomyces lavendulae subsp. CQ01819 was successfully obtained from soil. Targeted compounds purification led to discovering AHBA-derived mitomycin C, polyether antibiotic monensin A and valindolmycin.[Conclusion] Our findings provide a good example for efficiently discovering bacterial resource of expected natural products.
Jiaming Qi , Dongxu Zhang , Shaoli Wang , Libin Huang , Lili Xia , Wangyang Dong , Qiang Zheng , Qing'e Liu , Jianzhong Xiao , Zhiwen Xu
2020, 60(5):912-923. DOI: 10.13343/j.cnki.wsxb.20190353 CSTR: 32112.14.j.AMS.20190353
Abstract:[Objective] The prebiotic effect of xylo-oligosaccharides (XOS) has obtained much attention in recent years due to their fermentation properties. In this study, a kimchi-derived strain, Weissella confusa XU1 grew better on XOS than on glucose and xylose. The mechanism of XOS utilization by W. confusa XU1 was further explored. [Methods] Differential transcriptomes of W. confusa XU1, induced by XOS, glucose and xylose, were analyzed to identify the genetic loci involved in the uptake and catabolism of XOS. [Results] Transcriptome analysis reveals that several major facilitator superfamily (MFS) transporters and glycoside hydrolases were involved in the uptake and hydrolysis of XOS. In addition, glycolysis pathway and pentose phosphate pathway in W. confusa XU1 were enhanced when XOS were present, indicating that XOS were utilized more efficiently compared with other carbon sources. [Conclusion] This study reveals a proposed XOS utilization mechanism in W. confusa XU1.
Yu Wang , Jie Zhao , Zhihong Sun , Tiansong Sun , Heping Zhang
2020, 60(5):924-938. DOI: 10.13343/j.cnki.wsxb.20190368 CSTR: 32112.14.j.AMS.20190368
Abstract:[Objective] Streptococcus thermophilus is one of the most commonly used strains in fermented dairy industry. Therefore, it is important to screen S. thermophilus with good fermentation properties. [Methods] The genetic diversity and defense systems of 27 S. thermophilus genomes were analyzed using comparative genomics. [Results] The genetic diversity of S. thermophilus was high based on whole genome analysis. The phylogenetic tree built based on the core genes was divided into two clades, and the strains in Clade 2 were lack of the complete histidine synthesis pathway, thus could not grow normally in the medium lacking histidine. The analysis of defense systems of S. thermophilus reveals the same type of CRISPR locus and restriction modification system was fixed in the genome relatively. The numbers of CRISPR-Cas (P<0.05, r=0.43) and restriction modification systems (P<0.01, r=-0.59) correlated significantly with the number of genes encoding transposases, indicating S. thermophilus has evolved multiple defense systems to protect its genetic integrity by preventing the invasion of exogenous DNA. In addition, the number of CRISPR-Cas system of the Clade 1 strains was significantly (P<0.001) higher than the Clade 2 strains, whereas there was no significant difference in restriction modification systems. These results suggest that the Clade 1 strains had stronger capacity in resistance to phages. [Conclusion] The phylogenetic analysis based on the core genes was divided into two clades. There were some differences in histidine metabolism and defense system between the different clades, providing a new method for the rapid screening of S. thermophilus starters with excellent fermentation characteristics.
Hong Pan , Zhenhua Xie , Xiying Wang , Ying Zeng , Zhenxing Fang , Jing Wu
2020, 60(5):939-950. DOI: 10.13343/j.cnki.wsxb.20190369 CSTR: 32112.14.j.AMS.20190369
Abstract:[Objective] This study was done to understand the diversity of bacteria in the Wudalianchi volcanic region of China. [Methods] High-throughput sequencing with the Illumina MiSeq system was used to analyze the community composition and distribution of the bacteria occurring in different volcanic sediments of the Wudalianchi region. [Results] In total 23 categories of bacteria, including Firmicutes, Proteobacteria, Verrucomicrobia, Acidobacteria, Chloroflexi and Actinobacteria were found and further analyzed. Among them, the abundance of Firmicutes and Proteobacteria were higher, and Bacillus was the predominant genus. In addition, the homology of volcanic materials caused that the metabolic pathways of bacteria were mostly related to the biochemical cycle of C, N, S and Fe, therefore there was a certain degree of similarity between the community structure and function of the bacteria. However due to differences in sedimentary components, environmental factors and geological evolution in different research regions, some populations of Bacillus, Geobacter, Acidobacterium, Gallionella and Blastocatala were distributed differently in volcanic sediments with typical regional adaptability. [Conclusion] It showed that microbial resources were abundant in the volcanic sedimentary environments of the Wudalianchi region. Our results will provide the basic data for the future mining of functional microbial resources and further discussion of the relationship between microbial communities and volcanic environment.
Jianlong Xiao , Sitong Zhang , Xiaozhong Sun , Guang Chen
2020, 60(5):951-962. DOI: 10.13343/j.cnki.wsxb.20190373 CSTR: 32112.14.j.AMS.20190373
Abstract:[Objective] To obtain engineered Saccharomyces cerevisiae with high-yield of lignin peroxidase. [Methods] We cloned a constitutive promoter PGK, an exogenous protein secretion signal peptide α-factor, lignin peroxidases (LiP) genes and a terminator CYC1. We constructed complete expression box (PαLC) by overlap extension PCR method. Then, we established expression vector of lignin peroxidase S. cerevisiae via rDNA integration method, to achieve multi-copy expression of lignin peroxidase in S. cerevisiae. Then, we identified the copy number via droplet digital PCR technology, to explore the relationship between the copy number and protein expression amount. [Results] We got the engineered strain of S. cerevisiae to produce lignin peroxidase with the copy number of 1, 2, 4, 5, 6, 7, 8, 9, 10, 11, 12 and 13 via rDNA integration method, through enzymatic activity determination, it shows that the enzymatic activity is as highest as 367 U/L when the copy number is 7. [Conclusion] In this study, lignin peroxidase was expressed in S. cerevisiae, and the relationship between gene copy number and enzyme activity was studied, which is of great significance to the development of lignin degradation technology.
Xiaomin Wang , Peng Xu , Chuan Rao , Weiwei Wang , Qiuli Yang , Jiuxian Xiong
2020, 60(5):963-971. DOI: 10.13343/j.cnki.wsxb.20190384 CSTR: 32112.14.j.AMS.20190384
Abstract:[Objective] This study aims to explore the characteristics of intestinal microflora of BALB/c mice infected with Streptococcus suis (S. suis) type 2 by studying the characteristics of fecal microflora. [Methods] The V3-V4 region of 16S rRNA hypervariable genes in fecal samples of BALB/c mice infected with S. suis Type 2 and healthy controls were sequenced using the Illumina MiSeq platform. The microbiota composition and diversity of fecal samples were compared and analyzed. [Results] Alpha and Beta diversity showed that the fecal microflora diversity and community composition were different between the infection group and the control group. The infection group had higher bacterial diversity and microbial community richness than that of the control group. At the phylum level, compared with the control group, the infection group increased the proportion of Firmicutes and Bacteroidetes which were beneficial microorganisms to enhance the immunity of the body, but also increased the proportion of opportunistic pathogen such as Proteobacteria, which enhanced the likelihood of illness. At family level, Ruminococcaceae occurred in both groups with significantly different proportion, accounting for 36.58% and 11.02% respectively. At the genus level, Ruminococcaceae UCG-002 and Lactobacillus were dominant in the infection group, while Spirochaetaceae GWE 2-31-10 and Treponema 2 were dominant in the control group. [Conclusion] There were remarkable differences in the types and dominant bacteria between the infection group and the control group. Our results provide insights into the community and diversity of fecal microflora and foundation for screening beneficial microflora and adjusting microflora to treat S. suis type 2 infection in the future.
Anqi Liu , Wei Zhang , Mingfeng Wang , Tougen Liao , Maoqiang He , Jinwei Ren , Ruilin Zhao
2020, 60(5):972-981. DOI: 10.13343/j.cnki.wsxb.20190408 CSTR: 32112.14.j.AMS.20190408
Abstract:[Objective] The aim of this study was to explore aromatic macrofungi resources, and obtain volatile aroma components.[Methods] An aromatic mushroom collected from northern Thailand was identified by combining the traditional morphological taxonomy and molecular phylogenetic analysis. HP20 macroporous resin and gas chromatography-mass spectrometry (GC-MS) were used to analyze the volatile components in fermentation broth. Then, carbon source, nitrogen source and inorganic salts were optimized. [Results] The fungus was identified as Marasmius jasminodorus. The analysis result suggests that the main aromatic compounds and their peak area percentage include linalool (33.11%), 5-Hydroxymethylfurfural (4.64%), 5-Thiazoleethanol, 4-methyl (4.55%), Maltol (4.49%), 2-Furanmethanol (4.46%), 2(3H)-Furanone, 5-heptyldihydro (2.20%), 2-Propanone and 1-hydroxy (2.18%). In addition, the optimal fermentation conditions of carbon source, nitrogen source and inorganic salts were maltose, yeast powder and KH2PO4. [Conclusion] The study shows that this macrofungi can produce a variety of volatile aroma components that are widely used in existing industrial production, such as linalool, and it has potential application in the production of natural flavor.
Huihui Jia , Xinyue Xie , Yuanyuan Pan , Zhengguang Ren , Gang Liu , Yanmin Wei
2020, 60(5):982-991. DOI: 10.13343/j.cnki.wsxb.20190410 CSTR: 32112.14.j.AMS.20190410
Abstract:Bacillus sp. is one of the most studied microorganisms in biological control of plant diseases. It is widely distributed in nature and has great potential in agriculture.[Objective] To identify strain BJ-6 and explore its biological control function.[Methods] We identified the strain BJ-6 by morphological characteristics, physiological and biochemical tests and 16S rRNA, gyrA and gyrB gene sequence analysis. We measured the antimicrobial spectrum of BJ-6 by antagonistic experiment and studied the biocontrol effects and growth promotion on melon seedlings by pot experiment. [Results] We identified strain BJ-6 as B. amyloliquefaciens through the phylogenetic analysis of 16S rRNA, gyrA and gyrB sequences, and the characteristics of morphology, physiology and biochemistry. We found that BJ-6 strain had the bioactivity against 15 plant pathogens by the antagonistic experiment. The fermentation broth of BJ-6 had very good control efficiency to bacterial fruit blotch of melon seedlings in the pot experiment. Pot tests also showed that BJ-6 strain could promote the melon seedlings growth significantly. [Conclusion] We identified BJ-6 strain as B. amyloliquefaciens. Due to its broad spectrum of inhibiting plant pathogens and plant growth promoting ability, this stain had a good development value as biocontrol agents in plant protection.
Cuiling Xiong , Yu Du , Ruirong Feng , Haibin Jiang , Xiaoyu Shi , Haipeng Wang , Xiaoxue Fan , Jie Wang , Zhiwei Zhu , Yuanchan Fan , Huazhi Chen , Dingding Zhou , Yanzhen Zheng , Dafu Chen , Rui Guo
2020, 60(5):992-1009. DOI: 10.13343/j.cnki.wsxb.20190421 CSTR: 32112.14.j.AMS.20190421
Abstract:[Objective] This study aimed to reveal miRNA-mediated mechanism underlying Ascosphaera apis infection of Apis cerana cerana larvae. [Methods] Small RNA (sRNA) dataset of A. apis during infection (AaT) was screened out from sRNA-seq data from Ascosphaera apis-infected A. c. cerana 6-day-old larval guts. The filtered sRNA datasets from the purified spores (AaCK) and AaT were aligned against miRBase using Blast, followed by analyses of number and structural characteristics of pathogen miRNAs before and after Ascosphaera apis infection. Prediction, GO categorization and KEGG pathway enrichment analysis of targets of DEmiRNAs were conducted using related software. The regulation network between DEmiRNAs and corresponding targets was visualized using Cytoscape. Stem-loop RT-PCR, qPCR and molecular cloning were used to verify the reliability of our sequencing data. [Results] Totally, 380 and 387 miRNAs were identified in AaCK and AaT, respectively. The length of Ascosphaera apis miRNAs were mainly distributed between 18 nt and 25 nt; and the first base had a U bias. There were 155 up-regulated and 115 down-regulated miRNAs in AaCK vs AaT, targeting 6091 and 6145 mRNAs. Targets of DEmiRNAs were involved in 15 biological processes, 12 cell components and 11 molecular functions. Additionally, these targets were engaged in 123 pathways, regulating material metabolisms, energy metabolisms and signaling pathways. Moreover, complex regulation networks existed between DEmiRNA and corresponding targets, among them miR-29-x, miR-250-x, miR-4968-y, miR-11200-x, novel-m0023-5p, novel-m0130-5p and novel-m0135-5p can target mRNAs associated with cysteine proteinase, DNA methyltransferases and chitinase; miR-7-x, miR-9-z, miR-319-y and miR-5951-y can simultaneously regulate MAPK signaling pathway; miR-250-x may be involved in cross-kingdom regulation between A. apis and A. c. cerana larvae. [Conclusion] Our results revealed DEmiRNAs may participate in the infection process of A. apis via regulating targets associated with material and energy metabolisms, pathogen proliferation, virulence, and several signaling pathways; several key miRNAs including miR-7-x were potential targets for chalkbrood control.
Hongyun Jin , Mengyao Pan , Mingliang Wang , Qin Yan , Yaoxing Li , Rui Zhao , Heng Zhang , Peng Bai , Wei Liu
2020, 60(5):1010-1022. DOI: 10.13343/j.cnki.wsxb.20190425 CSTR: 32112.14.j.AMS.20190425
Abstract:[Objective] We studied how Acetobacter orientalis and Lactobacillus brevis regulate the oviposition preference of Drosophila melanogaster by oxygen concentration and further explored the biological significance of this phenomenon through the survival rate and developmental duration of offspring. [Methods] The egg-laying behavior of Drosophila melanogaster was analyzed by using a double selection device. The OD value and pH value of bacteria were measured by spectrophotometer and pH meter. The system that mediates the oviposition preference of Drosophila was detected by altering the visual, taste and olfactory senses of Drosophila. The biological significance was evaluated by the developmental duration and survival rate of offspring.[Results] Drosophila melanogaster tended to avoid laying egg on the side of Acetobacter orientalis, the oviposition index was -0.76, but liked to lay egg on the side of Lactobacillus brevis, and the oviposition Index was 0.5, the ratio of the two bacteria determined the oviposition selection of Drosophila melanogaster. Anaerobic environment reversed the oviposition preference to Acetobacter orientalis and Lactobacillus brevis. The OD value of Acetobacter orientalis was 1.3 in aerobic environment but 0.4 in anaerobic environment. The OD value of Lactobacillus brevis was 2.2 in both aerobic and anaerobic environment. Disrupting the sense of smell affected the Drosophila's oviposition to bacteria. Both Acetobacter orientalis and Lactobacillus brevis promoted the growth of Drosophila under anaerobic and aerobic environment, increased the survival rate by 1 and 1.5 times respectively, and shortened the development period of Drosophila by 1 and 2 days respectively. [Conclusion] Both Acetobacter orientalis and Lactobacillus brevis affected the oviposition preference of Drosophila, and the ratio of them determined the final oviposition selection. Acetobacter orientalis and Lactobacillus brevis had different metabolic modes by sensing the change of oxygen, and further regulated the oviposition preference of Drosophila. Olfactory system mediated the oviposition selection behavior of Drosophila melanogaster. Both Acetobacter orientalis and Lactobacillus brevis improved the survival rate of offspring and shorten the development duration.
Yanxia Wang , Zhihong Xie , Lei Zhang , Dayong Chang
2020, 60(5):1023-1035. DOI: 10.13343/j.cnki.wsxb.20190458 CSTR: 32112.14.j.AMS.20190458
Abstract:[Objective] To explore the effects of halophyte Sesbania cannabina and its rhizosphere functional microorganisms on ameliorating saline alkali soil, we isolated and identified the plant growth promoting rhizobacteria (PGPR) of S. cannabina grew in saline-alkali soil of Yellow River Delta, and further studied the growth-promoting and salt-tolerant characteristics of PGPRs. [Methods] Nitrogen-fixing, phosphorus-dissolving and potassium-dissolving bacteria were isolated from rhizosphere soil of S. cannabina by selective culture and identified by 16S rRNA molecular biology. Traits of plant growth-promoting and salt tolerance of the strains were determined and analyzed, and strains with excellent traits were selected to further study their growth promotion effect on corn. [Results] We totally obtained 105 rhizosphere isolates, of which N102 had growth-promoting and salt tolerance activities. As shown by seed germination test, N102 could significantly increase the germination rate (47%, P<0.05), bud length (48.5%, P<0.05), root length (60%, P<0.05) of S. cannabina. The pot experiment also shows that N102 could significantly improve plant height, root length, shoot dry weight, root dry weight and chlorophyll content of corn under salt stress. According to phylogenetic analysis, the similarity between N102 and Enterobacter soli ATCC BAA-2102 (NR117547) sequence was 99.30%, this it was identified as Enterobacter genus.[Conclusion] Strain N102 has high salt-tolerant and plant growth-promoting characteristics, promising to develop as microbial inoculants or microbial fertilizers that can effectively promote the growth of crops in saline-alkali soils.
Yanjun Zhang , Baoting Chen , Yumei Zhang , Yifei Zhang , Baolin Zhu , Pan Su , Linxian Ding , Naijun Xie , Pinghua Zhang
2020, 60(5):1036-1046. DOI: 10.13343/j.cnki.wsxb.20200020 CSTR: 32112.14.j.AMS.20200020
Abstract:[Objective] To analyze the composition and diversity of bacterial in silkworm excrement from Guangxi, and to explore microbial resource of silkworm excrement. [Methods] Through high-throughput sequencing technology, we analyzed the composition of bacterial communities in silkworm excrement. Meanwhile, we isolated culturable bacteria and those in viable but non-culturable (VBNC) state in silkworm excrement using spread-plate method and resuscitation promoting factor (Rpf)-based MPN method, and then classified and identified the isolated strains through 16S rRNA gene sequence analysis. [Results] The bacteria detected from silkworm excrement of Guangxi belonged to 10 phyla, 18 classes, 27 orders, 57 families and 96 genera, in which the bacteria abundance of 4 genera was greater than 1% and the dominant microflora was Enterobacter (Proteobacteria). We obtained 33 culturable bacteria from 14 genera through the spread-plate method, in which 4 genera (Citrobacter, Weissella, Chitinophaga, Pseudoclavibacter) were not detected by high-throughput sequencing. The detection abundance of bacteria increased by up to 100 times by Rpf-based MPN method. Also, we found 21 Rpf-sensitive and resuscitation-cultivable VBNC strains from the Rpf-treatment group, in which 6 genera (Paenibacillus, Caulobacter, Roseomonas, Pantoea, Erwinia, Acinetobacter) and 2 genera (Paenibacillus and Caulobacter) were not found through spread-plate method and high-throughput sequencing, respectively. [Conclusion] Our results provide a new perspective and a new approach for exploring and utilizing the microbial resources in silkworm excrement.
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