Genomics-guided discovery and structure identification of cyclic lipopeptides from the Bacillus siamensis JFL15

Abstract

In this research, a strain with broad-spectrum antimicrobial activities was isolated from the gastrointestinal tract of hairtail (Trichiurus haumela) and identified as Bacillus siamensis JFL15 through morphological, 16S rRNA, and average nucleotide identity analyses. The genome of B. siamensis JFL15 was sequenced, and three gene clusters involved in the biosynthesis of surfactin (srf), bacillibactin (dhb), and fengycin (fen) were predicted through antiSMASH analysis. The combined genomics-metabolics profiling of the strain revealed 20 active compounds, which belong to four main types of cyclic lipopeptides produced by Bacillus species: bacillibactin, iturin, fengycin, and surfactin. Among these lipopeptides, two high-purity antifungal components, namely, components b and c, were successfully identified as iturin A and bacillomycin F. The minimum inhibitory concentrations (MICs) of iturin A for Magnapothe grisea, Rhizoctorzia solani, and Colletotrichum gloeosporioides were 125.00, 62.50, and 125.00 μg/ml, respectively, whereas the MICs of bacillomycin F for these three organisms were 62.50, 31.25, and 62.50 μg/ml, respectively. The mechanism of bacillomycin F and iturin A against M. grisea was also investigated. Scanning electron microscopy (SEM) indicated that the surface of the hypha treated with iturin A or bacillomycin F became sunk, lumpy, and wrinkled. The diversity of the identified and predicted compounds from B. siamensis JFL15 suggested that this strain might be a promising biocontrol agent for an effective and environmentally friendly control of pathogenic microorganisms. To the best of our knowledge, this study is the first to describe cyclic lipopeptides purified and identified from B. siamensis.

Antifungal Activity of Cyclic Tetrapeptide from Bacillus velezensis CE 100 against Plant Pathogen Colletotrichum gloeosporioides

“…In this study, the BCF of B. velezensis CE 100 displayed significant antifungal activities against the pathogen, C. gloeosporioides, which causes anthracnose disease in plants. Results of in vitro tests suggested the involvement of secondary metabolites, consistent with findings from several previous studies stating the promiscuous action of the secondary metabolites against fungal pathogens [14][15][16][42][43][44][45]. In this study, we identified a cyclic tetrapeptide compound from B. velezensis CE 100 culture filtrate based on one-and two-dimensional NMR spectral analysis.…”

“…Bacillus species demonstrating wide array of bioactive metabolites have been recognized as effective candidates to control several phytopathogens [ 14 , 15 , 16 , 42 , 43 , 44 , 45 ]. In this study, the BCF of B. velezensis CE 100 displayed significant antifungal activities against the pathogen, C. gloeosporioides, which causes anthracnose disease in plants.…”

“…The role of active metabolites derived from biocontrol agents as viable and reliable alternatives to chemical fungicides cannot be underestimated [ 9 , 14 , 15 , 16 , 17 ]. Among various biocontrol agents, Bacillus species show strong abilities to restrict the growth of plant pathogens by synthesizing hydrolytic enzymes and antifungal compounds [ 14 , 15 , 16 , 18 , 19 ]. Moreover, Bacillus species are known to produce peptide antibiotics [ 20 , 21 , 22 ] used for biocontrol of agricultural crops [ 23 ].…”

“…Numerous microorganisms have been used for controlling fungal diseases including the diseases caused by C. gloeosporioides [ 14 , 15 , 16 ]. However, many researchers are focusing on antagonistic microorganisms that can more effectively control C. gloeosporioides and improve crop production and quality.…”

Screening of tomato seed bacterial endophytes for antifungal activity reveals lipopeptide producing Bacillus siamensis as a potential bio-control agent

“…A similar study conducted by Pan et al (2019) reported B. siamensis to produce sets of bacillibactins, fengycins, bacillomycins, and surfactins through the mining of genome and metabolic profiling. The PCR study demonstrated the existence of genes (i.e., surfactin synthetase D and bacillomycin synthetase D) involved in cyclic lipopeptide biosynthesis against multidrug-resistant aquatic bacterial pathogens (Xu et al, 2018). This concludes that so far, no endophytic strain of B. siamensis with antifungal potential has been reported to produce surfactin and Bacillomycin D. Complete isolation and identification of these lipopeptides from B. siamensis KCTC 13613(T) isolated from the varieties of tomato plants is first to be reported.…”