Yamanashi, Y. | bioRxiv Science

bioRxiv2021

Bacillus subtilis with a 1% population enhances the activity of Enterococcus faecalis with a 99% population

Microbes are present as communities in the environment. However, the importance of minor populations has not been well studied experimentally. In this study, we evaluated the role of Bacillus subtilis with a 1% population and its effect on co-incubated Enterococcus faecalis with a 99% population. Here we used an azo dye-decolorizing Enterococcus faecalis strain T6a1 and non-dye-decolorizing Bacillus subtilis strain S4ga. The dye decolorization assay enabled the investigation of the effects of B. subtilis S4ga on the activity of E. faecalis T6a1, even when B. subtilis S4ga was present at only 1% relative abundance or lower. We found that non-decolorizing B. subtilis S4ga enhanced the dye decolorization activity of E. faecalis T6a1, shortened the lag time of E. faecalis T6a1 to start decreasing the dye concentration, and increased the time for E. faecalis T6a1 to continue dye decolorization. These effects were correlated with redox potential values. We compared the extracellular amino acids between each incubation culture of E. faecalis T6a1 and B. subtilis S4ga, which revealed their mutual relationship by cross-feeding of specific amino acids. We also compared the intracellular primary metabolites between co-incubation and sole incubation of E. faecalis T6a1. The arginine deiminase (ADI) pathway in the co-incubated E. faecalis T6a1 was activated compared to that of E. faecalis T6a1 incubated solely. These findings explained that co-incubation with B. subtilis S4ga promoted ATP production in E. faecalis T6a1 cells to a greater extent and enhanced dye-decolorization activity. IMPORTANCEThis study highlights the importance of minor bacterial populations and their effects on major populations. We used Enterococcus faecalis as the major population and Bacillus subtilis as the minor population. Both species are becoming increasingly important. Some strains of E. faecalis are antibiotic-resistant pathogens, show probiotic effects, or are applicable for textile wastewater treatment. Some strains of B. subtilis are known to produce antimicrobial agents, reduce intestinal inflammation, or restore gut microbiota. We demonstrated that a low abundance of B. subtilis with 1% population increased the amount of energy produced by E. faecalis with 99% population, which appeared as enhanced dye decolorization activity of dye-decolorizing E. faecalis. Metabolomic analysis suggested that E. faecalis and B. subtilis had a mutual relationship by feeding specific amino acids to each other. These results provide new insights into co-existing minor populations in microbial communities and will improve our understanding of bacterial control. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=155 SRC="FIGDIR/small/462685v2_ufig1.gif" ALT="Figure 1"> View larger version (35K): org.highwire.dtl.DTLVardef@950ce8org.highwire.dtl.DTLVardef@1826200org.highwire.dtl.DTLVardef@f02e5forg.highwire.dtl.DTLVardef@749e07_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2020

Social relationships among captive male pygmy slow lorises (Nyctycebus pygmaeus): Is forming male same-sex pairs a feasible management strategy?

Little is known about the social behavior of pygmy slow lorises, in particular, the social relationships of same-sex individuals have rarely been investigated. The Slow Loris Conservation Center was built at the Japan Monkey Center to enhance the welfare of confiscated slow lorises, promote their conservation, improve public education and perform scientific research on the species. In the course of improving housing conditions, several same-sex pairs of pygmy slow lorises were formed. We monitored their behaviors and fecal glucocorticoid metabolite (FGM) levels to understand whether male same-sex pairings could be a feasible management strategy. The subjects were 10 male and 6 female lorises for comparison, all of whom were over five years old. We successfully formed five pairs of male lorises after eight formation attempts. Male pairs initially showed some aggressive behaviors; however, the rate decreased approximately 10 days after introduction. All of the male pairs eventually exhibited extensive affiliative social behaviors, including allogrooming and social play, during the dark (active) phase, and sleep site sharing during the light (inactive) phase. The rate of sleep site sharing during the light phase was higher than expected, suggesting that the pairs preferred to stay near each other. There was no evidence of increased stress after a long period of male-male social housing. Female same-sex pairs and male-female pairs demonstrated a high level of affiliative behaviors right after introduction. These results highlight the flexibility and high sociability of this species and indicate that such same-sex pairings are a feasible option for their social management.

zoology↗