Cellulose-dependent expression and antibacterial characteristics of surfactin from Bacillus subtilis HH2 isolated from the giant panda

Abstract

Surfactin secreted by Bacillus subtilis can confer strong, diverse antipathogenic effects, thereby benefitting the host. Carbon source is an important factor for surfactin production. However, the mechanism that bacteria utilize cellulose, the most abundant substance in the intestines of herbivores, to produce surfactin remains unclear. Here, we used B. subtilis HH2, isolated from the feces of a giant panda, as a model to determine changes in surfactin expression in the presence of different concentrations of cellulose by quantitative polymerase chain reaction and high-performance liquid chromatography. We further investigated the antimicrobial effects of surfactin against three common intestinal pathogens (Escherichia coli, Staphylococcus aureus, and Salmonella enterica) and its resistance to high temperature (60–121°C), pH (1–12), trypsin (100–300 μg/mL, pH 8), and pepsin (100–300 μg/mL, pH 2). The results showed that the surfactin expressed lowest in bacteria cultured in the presence of 1% glucose medium as the carbon source, whereas increased in an appropriate cellulose concentration (0.67% glucose and 0.33% cellulose). The surfactin could inhibit E. coli and Staphylococcus aureus, but did not affect efficiently for Salmonella enterica. The antibacterial ability of surfactin did not differ according to temperature (60–100°C), pH (2–11), trypsin (100–300 μg/mL), and pepsin (100–300 μg/mL; P > 0.05), but decreased significantly at extreme environments (121°C, pH 1 or 12; P < 0.05) compared with that in the control group (37°C, pH = 7, without any protease). In conclusion, our findings indicated that B. subtilis HH2 could increase surfactin expression in an appropriate cellulose environment and thus provide benefits to improve the intestinal health of herbivores.

Dynamics of Gut Microbiome in Giant Panda Cubs Reveal Transitional Microbes and Pathways in Early Life

“…Resisting the propagation of these microbes is of great importance for keeping cubs healthy. Apart from certain members of Bacillaceae that are able to secrete antipathogenic surfactin (Zhou et al, 2018), both Lactobacillus and Bifidobacterium show antimicrobial activities (Liu et al, 2017), and aid milk digestion by converting lactose into lactic acid. The abundance of Lactobacillus and Bifidobacterium increased quickly after the birth of the cubs, but declined rapidly in adults, particularly Bifidobacterium .…”

“…Lactobacillus and Bifidobacterium were enriched during breast or formula feeding, yet sharply decreased in adults. Bifidobacterium significantly promoted the pathway ‘proteasome’ in 6 ~ 9-month-old cubs, aiding proteolytic degradation and maintaining stability of cells (Wang and Maldonado, 2006), which expanded the gut microbiota defense system of giant panda (Hall-Stoodley et al, 2004; Zhou et al, 2018). Besides, Bifidobacterium was reported to take part in cellulose degradation (Yang et al, 2018).…”

“…Disorder of gut microbiota structure can be triggered by an abnormal increase in internal enteropathogens or invasion by exogenous pathogens (Zhao et al, 2017a; Zhang et al, 2017). In contrast, biofilm (Hall-Stoodley et al, 2004) or surfactin (Zhou et al, 2018) secreted by internal microbes of giant panda can stabilize the gut microbial structure.…”

Induction of Systemic Resistance in Maize and Antibiofilm Activity of Surfactin From Bacillus velezensis MS20

“…Likewise, earlier studies have also shown that in the presence of fibers, fever, and high salt in fermentation medium results in selective up-regulation of certain genes to resist exposure to elements in an exigent environment by secretion of some proteins for protection of cells as a defense mechanism ( Zhou et al, 2015 ). A recent q-RTPCR study by Zhou et al (2018) and Choub et al (2021) reported lowest fold gene expression (surfactin sfp gene) in 1% glucose and highest expression in the presence of a combination of 0.67% glucose and 0.33% cellulose. In the present study we have shown enhanced s rf A-A gene expression by q-RTPCR in the presence of 2% glucose and 0.5% MgSO 4 which upregulated to 9.34 ± 11 -fold in comparison with controls where gene expression was found to be 8-fold less when treated with glucose (1.03 ± 0.1) and MgSO 4 (1.06 ± 0.1) individually and in untreated controls (1.01 ± 0.1) carbon source; this study can be considered as an early report.…”

In-Vitro Antibacterial and Anti-Inflammatory Effects of Surfactin-Loaded Nanoparticles for Periodontitis Treatment

“…Surfactin is a surface-active biomolecule that has low toxicity, biodegradability, and can survive in extreme pH and temperature conditions [ 51 ]. It was noted that surfactin produces antimicrobial activity by leakage and lysis of lipid membranes of the targeted organisms [ 61 ]. However, the nanocarrier provides a suitable environment for the effective delivery of therapeutic agents.…”