Plantazolicin(Humboldt-Universität zu Berlin)

Bacillus velezensis MFSS1 (previously known as B. subtilis FS6) was reported to have good probiotic criteria and antibacterial activity against Vibrio spp. and Aeromonas spp., through phenotypic analysis. However, whole genome sequencing is required for commercialising a new probiotic, especially due to reports on probiotics that can cause horizontal gene transfer towards the host microbiome. Therefore, this study aims to investigate the comprehensive genomic characteristics of B. velezensis MFSS1, focusing on its antimicrobial genes against aquaculture pathogens, its probiotic traits, and safety assessment. The bacterial genome was sequenced using Oxford Nanopore sequencing, resulting in 7 contigs with a total length of 3,914,361 base pairs and an average G + C content of 46.58 %. The analysis using ContEst16S and average nucleotide identity revealed that the bacterium previously reported as B. subtilis is actually B. velezensis. Additionally, secondary metabolites against pathogens were predicted using the antiSMASH website, which identified eight secondary metabolites: Bacillibactin, Bacilysin, Surfactin, Difficidin, Fengycin, Bacillaene, Macrolactin H, and Plantazolicin. Furthermore, several probiotic markers were detected, functioning in acid tolerance, bile salt tolerance, adhesion, osmotic stress, and intestinal persistence during the delivery of the bacteria to the host. Interestingly, the in silico safety assessment of the bacterium revealed a lack of 96 antibiotic resistance genes and confirmed it as non-pathogenic to humans, compared with genomic bacteria from ATCC. The study indicates that B. velezensis MFSS1 is a good probiotic through genomic analysis and can be commercialised to control aquaculture pathogens and reduce reliance on antibiotics.

Bacillus safensis 2T-2 was isolated from potable water at a municipal water treatment facility in the North West province of South Africa, representing the first report of this species in treated drinking water systems. Whole genome sequencing revealed a 3.78 Mb genome with 41.3 % GC content and 4000 coding sequences distributed across 126 contigs. Genome analysis identified six antibiotic resistance genes, including vancomycin resistance genes (vanT, vanY), fosfomycin resistance (fosBx1), chloramphenicol resistance (cat86), and two disinfectant resistance genes (qacG, qacJ). Despite the presence of resistance genes, PathogenFinder analysis confirmed low pathogenic potential (0.168 probability). The strain demonstrated significant biosynthetic capabilities with 12 secondary metabolite gene clusters, including antimicrobial compound production (plantazolicin), biosurfactants (lichenysin), siderophores (bacillibactin, schizokinen), and the lipopeptide fengycin. Five bacteriocin gene clusters were identified, containing three core peptide genes (UviB, plantazolicin, pumilarin) with associated modification and transport genes. Phylogenetic analysis positioned strain 2T-2 closest to B. safensis F0-36b, confirming species identification. These findings highlight the dual nature of environmental bacteria in water systems, possessing both concerning antibiotic resistance traits and beneficial biotechnological potential, emphasizing the need for enhanced water treatment strategies while revealing opportunities for bioactive compound discovery.