Exploitation of Potentially New Antibiotics from Mangrove Actinobacteria in Maowei Sea by Combination of Multiple Discovery Strategies

Abstract

Rediscovery of known antibiotics from actinobacteria, especially Streptomyces, has become a bottleneck issue. Nowadays, more specific identification and dereplication could be acquired by a combination of modern analytic techniques with various databases. In this study, 261 actinobacterial strains were isolated from 8 mangrove soil samples by culture-dependent method. A total of 83 strains were selected to evaluate antibacterial activities and mechanisms by disc diffusion method and a unique double fluorescent protein reporter system (pDualrep2), respectively. Thirty-two strains exhibited antagonistic activity against at least one of the “ESKAPE” pathogens. Four Streptomyces strains (B475, B486, B353, and B98) showed strong inhibitory activity against Gram-positive bacteria and induced DNA damage SOS response. One Micromonospora strain (B704) exhibited inhibitory activity against several pathogens and induced attenuation-based translational inhibitors reporter. Seven members of quinoxaline-type antibiotics including quinomycin A, quinomycin monosulfoxide, and other five putative new analogues were found from the culture broth of strain B475 by a combination of anti-MRSA guide, HPTLC, HPLC-UV, and UPLC-UV-HRESIMS/MS analysis, Chemspider searching, and MS/MS-based molecular networking analysis. In conclusion, this study not only demonstrated that mangrove is a rich source of actinobacteria with the potentially new antibiotics but showed rapid dereplication of known antibiotics in the early stage can improve efficiency for the discovery of new antibiotics.

Bioprospecting of Soil-Derived Actinobacteria Along the Alar-Hotan Desert Highway in the Taklamakan Desert

“…To gain a comprehensive understanding of chemical diversity in the cultural broth of strain 16Sb2-4, UPLC-QTof-MS/MS-based dereplication analyses coupled with molecular networking were performed prior to the metabolites isolation. Many researches have reported the successful application of molecular networking for effective chemical dereplication and novel metabolite discovery ( Duncan et al, 2015 ; Kleigrewe et al, 2015 ; Esposito et al, 2017 ; Nothias et al, 2018 ; Lu et al, 2019 ), especially in our latest research on endophytic actinobacteria from psammophytes in Taklamakan desert, it has successfully contributed to the discovery of two new griseoviridin-type antibiotics from the fermentation broth of an endophytic Streptomyces strain ( Wang et al, 2020a ). In the present study, four families of bioactive compounds were observed and predicted from the crude extract of strain 16Sb2-4, including lipopeptides, cyclic depsipeptides, 22-membered macrolactams, and 16-membered macrolides.…”

Hetiamacin E and F, New Amicoumacin Antibiotics from Bacillus subtilis PJS Using MS/MS-Based Molecular Networking

“…8P21H-1, and the speculation about the existence of five putative new quinoxaline-type antibiotics in the fermentation broth of Streptomyces sp. B475 [ 37 , 38 ]. Comparison of traditional untargeted or bioassay-guided approaches, molecular networking is fast, requiring minimal time and sample material.…”

Isolation, Selection and Antimicrobial Activity of Actinomycetes from Mangrove Soil of Can Gio Forest, Hochiminh City, Vietnam

“…Streptomyces tanashiensis isolated from mangrove forest soil Maowei, China, it had the ability of antibacterial activity to Bacillus cereus (Lu et al, 2019). According to Johnson and Dietz (1968),Streptomyces tanashiensis synthesized and secrete out to luteomycin (antifungal), mithramycin (anticancer), phosphoramidon (inhibition of enzyme thermolysin from Bacillus spp.)…”