Structure determination of two new sesquiterpenoids from Streptomyces sanglieri
Sesquiterpenoids are a group of abundant and structurally diverse secondary metabolites mainly derived from plant and fungi. By contrast, they are rarely isolated from bacteria, and the terpene synthase genes had been considered to be silent in prokaryotes. Recently, more and more terpenes were identified from bacteria, and the biosynthesis of some terpenes has been discussed in heterologous bacteria. Actually, it demonstrated that the terpene synthases are widely distributed in bacteria, including streptomycete, and some new sesquiterpenoids and diterpenoids had been obtained through heterologous expression of terpene synthase genes derived from Streptomyces microorganism. In our ongoing investigation of new bioactive natural products from streptomycete, two new sesquiterpenes, 15-hydroxy-(+)-epicubenol (1) and 7β-hydroxy-7-epi-α-eudesmol (2), were identified from a fermentation broth of Streptomyces sanglieri (YIM 121209-2), which was isolated from the forest soil sample collected from Wuyi Mountain, Fujian Province, China. The structures of compounds 1 and 2 (Fig. 1) were elucidated based on detailed spectroscopic data analyses, including 1D and 2D NMR techniques. The cytotoxicity against two human cancer cell lines and antimicrobial activity against a panel of bacteria and fungi of 1 and 2 were evaluated. None of them showed cytotoxic or antimicrobial activities at 100μg/ml.
Toluene degradation via a unique metabolic route in indigenous bacterial species
Tanneries are the primary source of toluene pollution in the environment and toluene due to its hazardous effects has been categorized as persistent organic pollutant. Present study was initiated to trace out metabolic fingerprints of three toluene-degrading bacteria isolated from tannery effluents of Southern Punjab. Using selective enrichment and serial dilution methods followed by biochemical, molecular and antibiotic resistance analysis, isolated bacteria were subjected to metabolomics analysis. GC–MS/LC–MS analysis of bacterial metabolites helped to identify toluene transformation products and underlying pathways. Three toluene-metabolizing bacteria identified as Bacillus paralicheniformis strain KJ-16 (IUBT4 and IUBT24) and Brevibacillus agri strain NBRC 15538 (IUBT19) were found tolerant to toluene and capable of degrading toluene. Toluene-degrading potential of these isolates was detected to be IUBT4 (10.35 ± 0.084 mg/h), IUBT19 (14.07 ± 3.14 mg/h) and IUBT24 (11.1 ± 0.282 mg/h). Results of GC–MS analysis revealed that biotransformation of toluene is accomplished not only through known metabolic routes such as toluene 3-monooxygenase (T3MO), toluene 2-monooxygenase (T2MO), toluene 4-monooxygenase (T4MO), toluene methyl monooxygenase (TOL), toluene dioxygenase (Tod), meta- and ortho-ring fission pathways. But additionally, confirmed existence of a unique metabolic pathway that involved conversion of toluene into intermediates such as cyclohexene, cyclohexane, cyclohexanone and cyclohexanol. LC–MS analysis indicated the presence of fatty acid amides, stigmine, emmotin A and 2, 2-dinitropropanol in supernatants of bacterial cultures. As the isolated bacteria transformed toluene into relatively less toxic molecules and thus can be preferably exploited for the eco-friendly remediation of toluene.
Diversity, Bioactivity and Drug Development of Cultivable Actinobacteria in Six Species of Bird Feces
In order to provide new lead compounds of drugs and other useful products, the diversity and some bioactivities of cultivable actinobacteria in bird feces were studied．Six species of bird fecal samples were collected from Yunnan Wild Animal Park and bank of Dian Lake. The pure cultures of actinobacteria were isolated from these samples by using 6 different media. The partial 16S rRNA gene sequences of 207 selected strains were determined, the phylogenetic analysis was carried out, and antimicrobial activities were determined by using agar diffusion method. The key biosynthase genes (CYP, AHBA and SAL) of antibiotics were also detected. Total 28 genera of actinobacteria from all the samples were identified. 18 genera were identified from Pavo cristatus feces, and the actinomycete community was the most complex. These actinobacteria had wide inhibition against 10 test microbes. In 30, 25, and 36 strains of actinobacteria isolated from Pavo cristatus, Grus japonensis and Larus ridibundus feces respectively, average 22.2%, 8.9% and 40.8% strains had the key biosynthase genes encoding CYP, AHBA and SAL. More than 30 bioactive secondary metabolites from several actinomycete strains of bird feces were isolated and characterized. The study shows that birds fecal actinobacteria are a new potential source for discovering new drugs and other industry products.