Integrated Phenotypic and Genomic Characterization of Endophytic Bacillus vallismortis E4 for Biopolymer and Lipopeptide Production

Biopolymers are valuable alternatives to plastics because of their biocompatibility and biodegradability. Biopolymers and lipopeptides have been documented for Bacillus vallismortis; however, its whole-genome sequence (WGS) remains understudied and scarce in public databases. This study analyzed the WGS of endophytic B. vallismortis E4 and its potential for biopolymer and lipopeptide production. The genome showed 43.83% GC content with 4,128,106 bp in a total of 76 contigs. Functional annotation revealed 4167 genes, with 3943 protein-coding sequences. The genome contained genes for nitrogen fixation, stress tolerance, and metabolic pathways relevant to plant growth-promoting attributes. Genes for biosurfactant and polysaccharide synthesis were identified. PHB-related genes were limited to acetyl-CoA acetyltransferase and 3-hydroxybutyryl-CoA dehydrogenase, and canonical phaC and phaB were not detected. Nonetheless, these detected genes were complemented by the corresponding phenotypes. Biosurfactant production was confirmed by oil displacement area (36.65 ± 0.38 cm2) and emulsification index (49.66 ± 3.51%). PHB production was low (5.47 ± 0.12% of dry cell weight) and requires optimization. FTIR preliminarily identified the polymer as PHB, and SEM showed a slightly rough surface with spherical structures. The yield of cell-associated EPSs was 35.3 ± 0.1 mg/100 mL and was visualized using FTIR spectra, while AFM and XRD indicated its spherical and crystalline structure, respectively. The preliminary non-pathogenicity assessment of E4 suggests its suitability for industrial use, although the presence of diverse AMR genes needs to be further validated through physiological and phenotypic studies.