Bacillus subtilis TR47II as a source of bioactive lipopeptides against Gram-negative pathogens causing nosocomial infections

Abstract

This study aimed to investigate the antimicrobial, antibiofilm, and cytotoxic effects of biosurfactant lipopeptides synthesized by Bacillus subtilis TR47II. For this purpose, the lipopeptides were partially purified using a three-step process and characterized. In the first step, the crude extract obtained from acid precipitation exhibited strong antibacterial activity against the Gram-negative opportunistic pathogens Alcaligenes faecalis ATCC 8750, Achromobacter xylosoxidans ATCC 13138, Pseudomonas alcaligenes ATCC 14909, and Pseudomonas putida ATCC 15175. Moreover, partial inhibition was observed against Klebsiella aerogenes ATCC 13048 (42%), Escherichia coli ATCC 25922 (16%), and Pseudomonas aeruginosa ATCC 27853 (47%). The lipopeptides in the crude extract were extracted with methanol and fractioned on a silica gel chromatography column, rendering four TLC-pooled chromatographic fractions, named F1, F2, F3, and F4. The chromatographic fraction F4 was the most bioactive, with MIC values between 300 and 600 µg mL −1. Besides, F4 at sub-MIC doses dislodged the biofilms of A. faecalis, A. xylosoxidans, and P. alcaligenes by about 100, 85, and 81%, respectively. No cytotoxic effect was observed in mammalian cells at MIC. MALDI-TOF-MS analysis revealed that F4 contained cyclic lipopeptides belonging to two families: iturins (m/z 1004 to 1087) and fengycins (m/z 1424 to 1545). The dual effect of F4 on planktonic and sessile growth could suggest that the synergistic application of these biosurfactants could be efficient in the control of these opportunistic pathogens.

Endophytic Bacillus altitudinis Q7 from Ginkgo biloba inhibits the growth of Alternaria alternata in vitro and its inhibition mode of action

“…Cyclic lipopeptides have a wide range of biological activities, including antimicrobial, antiviral, anticancer and immunosuppressive activities, and have specific mechanisms that affect membrane permeability, eventually leading to cell disuption [41]. The same conclusion was obtained among studies of Fernanda (2020), their result showed the lipopeptides'capability to disturb the structure and functions of biological membranes, leading to the increased membrane permeability [42]. Ongena and Jacques [43] used a versatile weapons for plant disease biocontrol to describe Bacillus lipopeptides and the recent investigations have shed light on the fact that lipopeptides play a key role in the beneficial interaction of Bacillus species with parasitic plants by stimulating its host defence mechanisms.…”

A comprehensive description of the TolC effect on the antimicrobial susceptibility profile in Enterobacter bugandensis

“…It has been well characterized that Bacillus strains are able to synthesize various secondary metabolites, including fengycin, iturin, surfactin, difficidin, bacilysin, bacillibactin, bacillaene, amylocyclicin, subtilosin A, sublancin, and macrolactin, that possess antibacterial activity (Wilson et al, 1987;Scholz et al, 2014;Cavera et al, 2015;Liu et al, 2019;de Souza Freitas et al, 2020;Lv et al, 2020;Li et al, 2021a;Chakraborty et al, 2022;Erega et al, 2022;Zhou et al, 2022). There is a recent study showing that the transportation of bacilysin and bacillaene can be affected by RND-type transporters in Campylobacter jejuni (Erega et al, 2022).…”

Chemical diversity and cellular effects of antifungal cyclic lipopeptides from cyanobacteria

“…Hassallidins are so far the only known cyanobacterial antifungal cyclic lipopeptides with an exocyclic peptide moiety (Neuhof et al, 2005; Neuhof, Schmieder, et al, 2006). In this sense, they are analogous to the bacterial lipopeptide fengycin, which is shown to act on both bacteria and fungi but does not affect mammalian cells (de Souza Freitas et al, 2020; Desmyttere et al, 2019; Lin et al, 2020). Hassallidins were reported to possess promising antifungal activities with low minimum inhibitory concentration values ranging from 0.29 to 8.0 μM against Candida strains (Neuhof et al, 2005; Neuhof, Schmieder, et al, 2006; Neuhof, Seibold, et al, 2006; Shishido, Humisto, et al, 2015; Shishido, Jokela, et al, 2015).…”