Genotyping-Guided Discovery of Persiamycin A From Sponge-Associated Halophilic Streptomonospora sp. PA3

Microbial natural products have been a cornerstone of the pharmaceutical industry, but the supply of novel bioactive secondary metabolites has diminished due to extensive exploration of the most easily accessible sources, namely terrestrialStreptomycesspecies. The Persian Gulf is a unique habitat for marine sponges, which contain diverse communities of microorganisms including marine Actinobacteria. These exotic ecosystems may cradle rare actinomycetes with high potential to produce novel secondary metabolites. In this study, we harvested 12 different species of sponges from two locations in the Persian Gulf and isolated 45 symbiotic actinomycetes to assess their biodiversity and sponge-microbe relationships. The isolates were classified intoNocardiopsis(24 isolates),Streptomyces(17 isolates) and rare genera (4 isolates) by 16S rRNA sequencing. Antibiotic activity tests revealed that culture extracts from half of the isolates displayed growth inhibitory effects against seven pathogenic bacteria. Next, we identified five strains with the genetic potential to produce aromatic polyketides by genotyping ketosynthase genes responsible for synthesis of carbon scaffolds. The combined data led us to focus onStreptomonosporasp. PA3, since the genus has rarely been examined for its capacity to produce secondary metabolites. Analysis of culture extracts led to the discovery of a new bioactive aromatic polyketide denoted persiamycin A and 1-hydroxy-4-methoxy-2-naphthoic acid. The genome harbored seven gene clusters involved in secondary metabolism, including a tetracenomycin-type polyketide synthase pathway likely involved in persiamycin formation. The work demonstrates the use of multivariate data and underexplored ecological niches to guide the drug discovery process for antibiotics and anticancer agents

Isolation of ASR7 Actinomycete Isolated from S12 Demospongia Marine Sponge and Study of Its Antibacterial Activity

Background and Aims: Marine Actinomycetes are gram-positive bacteria that sometimes are free, saprophytic or plant and animal-associated, including marine sponges. More than 75% of antibiotics and antimicrobial compounds are produced by actinomycetes. In recent years, due to the need for new drugs, marine microorganisms have been considered as new sources of potential production of significant metabolites. The purpose of this study is isolation and identification of marine sponge-associated Actinomycete and investigation of its antibacterial activity. Materials and Methods: The Actinomycete was isolated from the marine Sponge collected from the depths of coastal waters in Bushehr and screened for antibacterial activity on pathogenic microorganisms of Escherichia coli، Bacillus cereus، Klebsiella spp.، Salmonella spp. and Proteus spp. using a Disk Diffusion Method. For molecular identification, genomic DNA was first extracted from isolate and then, the16S rDNA gene was amplified by PCR and Sequenced. The results were analyzed using bioinformatic programs, Bioedit and MEGA6. Results: In this study, based on phylogeny studies, it was determined that the isolate belonged to thegenus Streptomyces, and biochemical studies showed that all tests except catalase and gram were negative; antibacterial activity study showed significant activity against three pathogenic bacteria, E. coli, Bacillus cereus and Salmonella spp. It was more active against Salmonella spp. (around 16mm inhibition zone diameter). Conclusions: The results showed that depths of the Bushehr coastal waters have marine sponge associated actinomycetes, which are a source of secondary metabolites with biological activity

Vitellogenin Gene Expression and Sex Steroid Levels as Biomarkers in Yellowfin Seabream (Acanthopagrus latus) Exposed to Bisphenol-A

Background: The egg yolk precursor protein vitellogenin (VTG) has proven to be a useful biomarker, used to identify organisms exposed to estrogenic compounds. Methods: We investigated variations in the VTG gene expression pattern and plasma sex steroid hormones concentrations in the yellowfin Seabream, Acanthopagrus latus, (A. latus) by various doses of bisphenol-A (BPA) exposure for 7 and 14 days. We developed a quantitative real time polymerase chain reaction (RT-PCR) assay for the expression of VTG gene in A. latus. The dose-response pattern of VTG gene expression in A. latus exposed to various doses of BPA was characterized. In order to design RT-PCR primers specific to A. latus VTG, a partial sequence of the VTG gene was obtained. Results: The RT-PCR assay was effective in detecting increased VTG gene expression in A. latus exposed to BPA. It also demonstrated that the VTG expression was affected by BPA in a dose and time-dependent manner. Plasma testosterone (T) levels were decreased in the treated fish in comparison with those found in the control group, when they were exposed to 100 µg/g of BPA and 2 µg/g of E2. In contrast, the plasma levels of 17β-estradiol (E2) were significantly increased in a dose-dependent manner. Conclusion: The results suggest that VTG mRNA quantification can provide a sensitive and early signal in the detection of estrogens in marine wildlife. It also indicated that BPA could lead to an imbalance of sex steroid hormones with potentially harmful consequences on sexually immature male A. latus

Screening, isolation and study of antifungal activity of marine actinomycetes from Deylam nearshore sediments

Background: Marine actinomycetes, gram positive bacteria, have been prolific sources of novel secondary metabolites with a range of biological antibacterial activities. Marine sediments are potential sources for isolation of novel actinomycetes yielding new products and are recognized as source of novel antibiotic. In this study, we reported the isolation, characterization and antifungal activities of 8 actinomycetes isolated from Deylam nearshore sediments. Materials and Methods: The marine soil sediment samples were collected from Deylam nearshore at the depth of 10 cm. The treated samples were serially diluted and used starch casein agar as a culture medium. Morphological and biochemical characterization of isolated strain was carried out by using standard methods. Antifungal assay of the bacterial extracts was performed using standard well diffusion assay. Results: In this study, 8 marine actinomycetes were isolated from Deylam near shore sediments according to their morphology. All of isolate was belonged to Streptomyces genus. Differential analyses results for catalase and Gram test were positive for all isolates, the positive isolates for TSI, simmon citrate and ornitin decarboxylase were 1, 2 and 5 respectively, all isolates were negative for lysine decarboxylase, VP, MR and indol test, SIM test results showed that all isolates were non-motile, one isolate was produced H2S and some isolates formed pigmented colony. Most isolates showed antifungal activity against tested pathogenic fungi. Conclusion: Results of this investigation revealed that the marine actinomycetes of Deylam nearshore sediments were potent source of bioactive compounds with antifungal activity