Extraction, purification and structural elucidation of environmentally benign antifouling metabolite from Streptomyces thermolineatus VITKV6A

Marine actinomycetes are potential sources of secondary metabolites with wide range of applications. In the current study, Streptomyces thermolineatus VITKV6A, which was screened from our previous study, was mass cultivated to obtain the active compound. Analysis of crude extract of this isolate by Thin Layer chromatography (TLC) with the optimum solvent system (Methanol: Ethyl acetate, 40:60 v/v ratio) showed multiple bands at the retention factor values 0.9, 0.6 and 0.4 both under visible and UV light. The individual compounds in the crude extract were eluted by silica gel column chromatography. The antimicrofouling activity of fraction 2 showed antimicrofouling activity against biofilm forming bacteria Psychrobacter celer VITKV3, Psychrobacter alimentarius VITKV4 and Kocuria rhizhophila with MIC of 0.5, 0.75 and 0.75μg/ml respectively. Similarly, the antimacrofouling activity of fraction 2 was examined by mollusc foot adherence assay against Patella sp. The percentage of fouling and regaining decreased with increasing concentration, whereas complete inhibition of fouling was observed at a concentration of 1000μg mL−1. The bioactive compound exhibited low cytotoxicity and higher LC50 value of 173.72μg mL −1 against Artemia salina. HPLC analysis of the active fraction showed a single peak with retention time of 3.117 mins, which reveals the purity of the compound. Further, the active compound was characterized using gas chromatography coupled with mass spectroscopy (GC–MS), Fourier Transform Infrared Spectroscopy (FTIR) and NMR and identified as Oxycyclopentadien with alternative name 1,3-Cyclopentadien-1-ol. This compound is accountable for the antifouling properties of Streptomyces thermolineatus VITKV6A. •Bioactive compound from Streptomyces thermolineatus VITKV6A was characterized by analytical techniques.•Biofilm formation by marine bacteria was inhibited by the bioactive compound from Streptomyces thermolineatus VITKV6A.•The isolated bioactive compound deterred foot adherence by mollusc.•Benignity of the compound towards other organisms was corroborated by anticrustacean assay.