Structural and Functional Insights into Iturin W, a Novel Lipopeptide Produced by the Deep-Sea Bacterium Bacillus sp. Strain wsm-1

Abstract

In the present study, a deep-sea bacterial strain designated Bacillus sp. wsm-1 was screened to exhibit strong antifungal activity against many plant pathogenic fungi, and corresponding antifungal agents were thereby purified and determined by tandem mass spectrometry to be two cyclic lipopeptide homologs. These two lipopeptide homologs were identified to possess identical amino acid sequences of β-amino fatty acid-Asn-Ser-Asn-Pro-Tyr-Asn-Gln, which were different from any previously reported lipopeptides, and deduced as two novel lipopeptides designated as C14 iturin W and C15 iturin W, respectively. Electron microscopy observation indicated that both iturin W homologs caused obvious morphological changes and serious disruption of plasma membrane toward fungal cells, while C15 iturin W exhibited more serious cell damages than C14 iturin W did, which was consistent well with the results of the antifungal activity assays. To improve the yield and antifungal activity of iturin W, the effects of different carbon and nitrogen sources and amino acids on production of C14 iturin W and C15 iturin W were investigated, respectively. The results indicated that supplements of most of the detected carbon and nitrogen sources could increase the yield of C14 iturin W, but inhibit the yield of C15 iturin W, while supplements of tryptone and most of the detected amino acids could increase the yield of both C14 iturin W and C15 iturin W. IMPORTANCE Plant disease caused by pathogenic fungi is one of the most devastating diseases, which affects the food safety of the whole world to a great extent. Compared with traditional chemical control, biological control of plant diseases by microbial natural products is more desirable. In this study, we discovered a novel lipopeptide iturin W with promising prospect in biological control of plant diseases. Moreover, the effects of different carbon and nitrogen sources and amino acids on production of C14 iturin W and C15 iturin W would provide a reasonable basis for the optimization of fermentation process of lipopeptides. Notably, the structure of iturin W was different to any previously reported lipopeptides, suggesting deep-sea microorganisms might produce many novel natural products and have significant potentials to develop biological products in the future.

Characterization and Antimicrobial Studies of Iturin-Like and Bogorol-Like Lipopeptides From Brevibacillus spp. Strains GI9 and SKDU10

“…Initially, the detailed structure of iturin-A and bogorol A were elucidated by the use of nuclear magnetic resonance (NMR) (Garbay-Jaureguiberry et al, 1978;Barsby et al, 2001). Consequently, by utilizing the original primary structure as template, several analogs of iturins and bogorols were identified using mass spectrometry and reported (Rautenbach et al, 2001;Barsby et al, 2006;Zhou et al, 2020;Singh et al, 2021). Considering the role of purity of peptide for such studies, reversephase HPLC was used for the successful separation of unknown compounds in pure form (Figure 1B).…”

Characterization of Two Unique Cold-Active Lipases Derived from a Novel Deep-Sea Cold Seep Bacterium

“…The deep-sea sedimental samples were collected at a depth of 1146 m in the cold seep (22°06′58.598″ N 119°17′07.322″ E), P.R. China, in June 2018, and bacteria from the samples were isolated on the modified Zobell 2216E medium (5.0 g peptone, 1.0 g yeast extract, 15.0 g agar, a liter of filtered seawater, pH 7.0) at 28 °C as described previously [ 14 , 15 ]. To screen lipase-producing bacteria, isolated strains were cultivated in plates containing 2216E medium supplemented with 1% ( v / v ) Tween 80 [ 16 ].…”

Isolation, Identification and Characterization of Two Kinds of Deep-Sea Bacterial Lipopeptides Against Foodborne Pathogens

“…According to amino acid sequences and fatty acid branches, lipopeptides can be classified into three families: iturin, surfactin, and fengycin (Romero et al, 2007;Yang et al, 2015). Iturin is composed of heptapeptide containing β-amino fatty acids (Zhou et al, 2020). Surfactin is formed by a C 12 -C 16 β-hydroxy fatty acid linked to heptapeptide (Bonmatin et al, 1995).…”