Bacterial diversity and VBNC bacteria in silkworm excrement from Guangxi

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.