Bacillus subtilis subsp. subtilis CBMDC3f with antimicrobial activity against Gram-positive foodborne pathogenic bacteria: UV-MALDI-TOF MS analysis of its bioactive compounds

Abstract

In this work a new Bacillus sp. strain, isolated from honey, was characterized phylogenetically. Its antibacterial activity against three relevant foodborne pathogenic bacteria was studied; the main bioactive metabolites were analyzed using ultraviolet matrix assisted laser desorption-ionization mass spectrometry (UV-MALDI MS). Bacillus CBMDC3f was phylogenetically characterized as Bacillus subtilis subsp. subtilis after rRNA analysis of the 16S subunit and the gyrA gene (access codes Genbank JX120508 and JX120516, respectively). Its antibacterial potential was evaluated against Listeria monocytogenes (9 strains), B. cereus (3 strains) and Staphylococcus aureus ATCC29213. Its cell suspension and cell-free supernatant (CFS) exerted significant anti-Listeria and anti-S. aureus activities, while the lipopeptides fraction (LF) also showed anti-B. cereus effect. The UV-MALDI-MS analysis revealed surfactin, iturin and fengycin in the CFS, whereas surfactin predominated in the LF. The CFS from CBMDC3f contained surfactin, iturin and fengycin with four, two and four homologues per family, respectively, whereas four surfactin, one iturin and one fengycin homologues were identified in the LF. For some surfactin homologues, their UV-MALDI-TOF/TOF (MS/MS; Laser Induced Decomposition method, LID) spectra were also obtained. Mass spectrometry analysis contributed with relevant information about the type of lipopeptides that Bacillus strains can synthesize. From our results, surfactin would be the main metabolite responsible for the antibacterial effect.

Antifungal Activity of Isolated Bacillus amyloliquefaciens SYBC H47 for the Biocontrol of Peach Gummosis

“…However, surfactin had a similar suppressive effect on conidial germination as that of fengycin, and it had limited action on the growth of mycelia (Fig 6). This result was slightly different from that of previous research [52]. It is well-know that surfactin is an acidic lipopeptide, and it can destabilize of lipid-packing of membranes and induce content leakage, but the membrane-perturbing effect is attenuated by adding sterol [63].…”

“…Honey is a desirable food source that has attracted more attention because of the production of antifungal compounds from its bacterial isolates [24, 52]. In this study, 225 bacterial strains were isolated from raw honey, strain SYBC H47 had the strongest antifungal activity against B .…”

16S rRNA gene sequencing and MALDI-TOF mass spectrometry based comparative assessment and bioprospection of psychrotolerant bacteria isolated from high altitudes under mountain ecosystem

“…While the emerging MALDI biotyping is being popular in different fields of microbiology that has partly replaced conventional biochemical identification methods [12], variability of this methodology for the identification of microbes has been attributed to factors such as sample processing methods, matrix solutions, spectral quality, and data analysis methods [6,21]. The methodology is becoming more popular in clinical set-ups for speedy and low-cost microbial identification [28,34] and also in the analysis of bioactive compounds [46].…”

Biosurfactants Production Using Permeate from Whey Ultrafiltration and Bioproduct Recovery by Membrane Separation Process

“…, the MALDI‐MS spectrum with expansion in the m/z 1000–1140 region showed the characterization of the chemical structure of the biosurfactants produced by the bacteria. Ions of m/z 1044, 1058, and 1074 are homologous molecules of the biosurfactants identified as surfactin (Torres et al, ).…”