Antimicrobial Gageomacrolactins Characterized from the Fermentation of the Marine-Derived Bacterium Bacillus subtilis under Optimum Growth Conditions

Abstract

Marine bacteria are a potential source of structurally diversified bioactive secondary metabolites that are not found in terrestrial sources. In our continuous effort to search for new antimicrobial agents from marine-derived bacteria, we isolated bacterial strain 109GGC020 from a marine sediment sample collected from Gageocho, Republic of Korea. The strain was identified as Bacillus subtilis based on a 16s rRNA sequence analysis. After a 7-day fermentation of the B. subtilis strain under optimum growth conditions three new and four known secondary metabolites were discovered using chromatographic procedures, and their biological activities were evaluated against both bacteria and crop-devastating fungi. The discovered metabolites were confirmed by extensive 2D NMR and high-resolution ESI-MS data analyses to have the structures of new macrolactin derivatives gageomacrolactins 1-3 and known macrolactins A (4), B (5), F (6), and W (7). The stereoconfigurations of 1-3 were assigned based on coupling constant values, chemical derivatization studies, and a literature review. The coupling constants were very crucial to determine the relative geometries of olefins in 1-3 because of overlap of the ¹H NMR signals. The NMR data of these compounds were recorded in different solvents to overcome this problem and obtain accurate coupling constant values. The new macrolactin derivatives 1-3 displayed good antibiotic properties against both Gram-positive (S. aureus, B. subtilis, and B. cereus) and Gram-negative (E. coli, S. typhi, and P. aeruginosa) bacteria with minimum inhibitory concentration (MIC) values of 0.02-0.05 μM. Additionally, the antifungal activities of 1-7 were evaluated against pathogenic fungi and found to inhibit mycelial growth of A. niger, B. cinerea, C. acutatum, C. albicans, and R. solani with MIC values of 0.04-0.3 μM, demonstrating that these compounds were good fungicides.

Macrolactins from Marine-Derived Bacillus subtilis B5 Bacteria as Inhibitors of Inducible Nitric Oxide and Cytokines Expression

“…It was a newly isolated compound produced by deep-sea sediment of the Pacific Ocean. Many isolated macrolactins including epoxyl-macrolactin that have been isolated [19,20,21,22] and all macrolactins contain three separate diene structure elements.…”

“…Macrolactins, an important 24-membered macrolactones, are mainly produced by Bacillus [19,20,21,22]. In our previous study [19], a new macrolactin ( 2 ) and three known ones ( 3 – 5 ), were isolated from Bacillus subtilis B5 , a bacteria derived from the 3000-meter deep-sea sediment of the Pacific Ocean.…”

Integration of proteome and transcriptome data reveals the mechanism involved in controlling of Fusarium graminearum by Saccharomyces cerevisiae

“…The control of crop diseases with beneficial microorganisms or microbial metabolites is a strategy for biological control . There are some success stories where microbial biocontrol agents have been used to control the growth and reproduction of plant pathogens . The microorganisms used for biological control are mainly strains isolated from plants and soils in ecosystems, including bacteria, fungi and small amounts of actinomycetes that have antagonistic properties …”

“…10 There are some success stories where microbial biocontrol agents have been used to control the growth and reproduction of plant pathogens. 11,12 The microorganisms used for biological control are mainly strains isolated from plants and soils in ecosystems, including bacteria, fungi and small amounts of actinomycetes that have antagonistic properties. 13,14 Postharvest disease control using biological agents has especially attracted the attention of more and more researchers.…”

Antibacterial activity of marine bacteria isolated from marine sponges at Phu Quoc island, Vietnam

“…Trong đó, hợp chất lipopeptides thể hiện hoạt tính kháng các chủng nấm gây bệnh Rhizoctocnia solani, Botrytis cinerea và Colletotrichum acutatum với nồng độ ức chế tối thiểu (MIC) là 0,02-0,06 µM. Hợp chất gageopeptides và macrolactin có hoạt tính kháng lại một số chủng vi khuẩn Gram(-) và Gram(+) với giá trị MIC lần lượt là 0,04-0,08 µM và 0,02-0,05 µM [7,8]. Prem et al (2006) [5] đã phân lập được 75 chủng vi khuẩn từ 4 loài bọt biển (Echinodictyum sp., Spongia sp., Sigmadocia fibulatus và Mycale mannarensis) ở bờ biển Tuticorin, vịnh Mannar.…”