Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil.
Institute of Biosciences, University of São Paulo, São Paulo, SP, Brazil.
Appl Microbiol Biotechnol. 2023 Oct;107(19):6103-6120. doi: 10.1007/s00253-023-12712-z. Epub 2023 Aug 10.
Bacillus subtilis species complex is known as lipopeptide-producer with biotechnological potential for pharmaceutical developments. This study aimed to identify lipopeptides from a bacterial isolate and evaluate their antifungal effects. Here, we isolated and identified a lipopeptide-producing bacterium as a species of Bacillus subtilis complex (strain UL-1). Twenty lipopeptides (six iturins, six fengycins, and eight surfactins) were identified in the crude extract (CE) and fractions (F1, F2, F3, and F4), and the highest content of total lipopeptides was observed in CE and F2. The chemical quantification data corroborate with the hemolytic and antifungal activities that CE and F2 were the most hemolytic and inhibited the fungal growth at lower concentrations against Fusarium spp. In addition, they caused morphological changes such as shortening and/or atypical branching of hyphae and induction of chlamydospore-like structure formation, especially in Fusarium solani. CE was the most effective in inhibiting the biofilm formation and in disrupting the mature biofilm of F. solani reducing the total biomass and the metabolic activity at concentrations ≥ 2 µg/mL. Moreover, CE significantly inhibited the adherence of F. solani conidia on contact lenses and nails as well as disrupted the pre-formed biofilms on nails. CE at 100 mg/kg was nontoxic on Galleria mellonella larvae, and it reduced the fungal burden in larvae previously infected by F. solani. Taken together, the lipopeptides obtained from strain UL-1 demonstrated a potent anti-Fusarium effect inducing morphological alterations and antibiofilm activities. Our data open further studies for the biotechnological application of these lipopeptides as potential antifungal agents. KEY POINTS: • Lipopeptides inhibit Fusarium growth and induce chlamydospore-like structures. • Lipopeptides hamper the adherence of conidia and biofilms of Fusarium solani. • Iturins, fengycins, and surfactins were associated with antifungal effects.
枯草芽孢杆菌复合群是一种具有生物科技潜力的脂肽产生菌，可应用于药物开发。本研究旨在从细菌分离株中鉴定脂肽，并评估其抗真菌作用。在此，我们分离并鉴定了一种产生脂肽的细菌，为枯草芽孢杆菌复合群的一个种（菌株 UL-1）。在粗提物（CE）和各馏分（F1、F2、F3 和 F4）中鉴定出 20 种脂肽（6 种伊枯草菌素、6 种丰原素和 8 种表面活性剂），CE 和 F2 中的总脂肽含量最高。化学定量数据与溶血活性和抗真菌活性相符，CE 和 F2 具有最强的溶血活性，在较低浓度下即可抑制真菌生长，尤其是对镰刀菌属真菌。此外，它们还导致菌丝形态发生变化，如缩短和/或异常分枝，以及诱导类似于厚垣孢子的结构形成，尤其是在茄病镰刀菌中。CE 在抑制生物膜形成和破坏茄病镰刀菌成熟生物膜方面最有效，在浓度≥2µg/mL 时可降低总生物量和代谢活性。此外，CE 可显著抑制茄病镰刀菌分生孢子在接触镜和指甲上的黏附，并破坏指甲上预先形成的生物膜。CE 在 100mg/kg 时对大蜡螟幼虫无毒，且可降低幼虫中先前感染茄病镰刀菌的真菌负荷。综上所述，从菌株 UL-1 获得的脂肽具有诱导形态改变和抗生物膜活性的强效抗真菌作用。我们的数据为这些脂肽作为潜在抗真菌剂的生物技术应用提供了进一步的研究方向。
