Aims: This study was aimed to investigate the anti-inflammatory and anti-rheumatoid effects of the Bacillus amyloliquefaciens derived surfactin. Methodology and results: Crude and biosurfactant extracts were analyzed using thin-layer chromatography to determine the presence of biosurfactant. Both extracts were evaluated for their inhibitory effects against the acetylcholinesterase and 5-lipoxygenase enzymes. Human synovial cells were induced with TNF-α and IL-1β. The percentages of the cell viability for both normal and induced cells were determined with an MTT assay. Results showed that surfactin was detected in the biosurfactant extract and demonstrated higher inhibitory effects compared to the crude extract against both inhibitory enzymes acetylcholinesterse (IC50=30.60 μg/mL) and lipoxygenase (IC50=110.10 μg/mL). Both crudes showed no cytotoxic effects at the highest concentration used (50 μg/mL) against normal human synovial cells but showed active reactions against the induced cells. The anti-proliferative effects of biosurfactant and crude extracts were in dose-dependent manner. Conclusion, significance and impact of study Notably, surfactin obtained from B. amyloliquefaciens has shown an inhibitory effect against pro-inflammatory enzymes and cell viability of the induced rheumatoid arthritis cell line. These results highlighted the therapeutic potential of surfactin application as an anti-inflammatory agent for arthritis treatment. Further study is needed to elucidate the mechanisms underlying the anti-inflammatory effect of surfactin.
Bacillus amyloliquefaciens ; Surface-Active Agents ; Anti-Inflammatory Agents ; Rheumatoid Factor

Heme, which exists widely in living organisms, is a porphyrin compound with a variety of physiological functions. Bacillus amyloliquefaciens is an important industrial strain with the characteristics of easy cultivation and strong ability for expression and secretion of proteins. In order to screen the optimal starting strain for heme synthesis, the laboratory preserved strains were screened with and without addition of 5-aminolevulinic acid (ALA). There was no significant difference in the heme production of strains BA, BAΔ6 and BAΔ6ΔsigF. However, upon addition of ALA, the heme titer and specific heme production of strain BAΔ6ΔsigF were the highest, reaching 200.77 μmol/L and 615.70 μmol/(L·g DCW), respectively. Subsequently, the hemX gene (encoding the cytochrome assembly protein HemX) of strain BAΔ6ΔsigF was knocked out to explore its role in heme synthesis. It was found that the fermentation broth of the knockout strain turned red, while the growth was not significantly affected. The highest ALA concentration in flask fermentation reached 82.13 mg/L at 12 h, which was slightly higher than that of the control 75.11 mg/L. When ALA was not added, the heme titer and specific heme production were 1.99 times and 1.45 times that of the control, respectively. After adding ALA, the heme titer and specific heme production were 2.08 times and 1.72 times higher than that of the control, respectively. Real-time quantitative fluorescent PCR showed that the expressions of hemA, hemL, hemB, hemC, hemD, and hemQ genes at transcription level were up-regulated. We demonstrated that deletion of hemX gene can improve the production of heme, which may facilitate future development of heme-producing strain.
Gene Deletion ; Bacillus amyloliquefaciens/metabolism* ; Aminolevulinic Acid/metabolism* ; Heme/metabolism* ; Fermentation

In order to explore the effect of peptidoglycan hydrolase on the viable cell counts of Bacillus amyloliquefaciens and the yield of alkaline protease, five peptidoglycan hydrolase genes (lytC, lytD, lytE, lytF and lytG) of B. amyloliquefaciens TCCC111018 were knocked out individually. The viable cell counts of the bacteria and their alkaline protease activities before and after gene deletion were determined. The viable cell counts of the knockout mutants BA ΔlytC and BA ΔlytE achieved 1.67×10⁶ CFU/mL and 1.44×10⁶ CFU/mL respectively after cultivation for 60 h, which were 32.5% and 14.3% higher than that of the control strain BA Δupp. Their alkaline protease activities reached 20 264 U/mL and 17 265 U/mL, respectively, which were 43.1% and 27.3% higher than that of the control strain. The results showed that deleting some of the peptidoglycan hydrolase genes effectively maintained the viable cell counts of bacteria and increased the activity of extracellular enzymes, which may provide a new idea for optimization of the microbial host for production of industrial enzymes.
Bacillus amyloliquefaciens/genetics* ; Bacterial Proteins ; Cell Count ; Endopeptidases/genetics* ; N-Acetylmuramoyl-L-alanine Amidase/genetics*