Phylogenetic study of sponge associated bacteria from the Lakshadweep archipelago and the antimicrobial activities of their secondary metabolites

Abstract

Marine ecosystem of the Lakshadweep archipelago is unique and known to have a very high degree of biodiversity with a number of endemic flora and fauna. The present study focuses to isolate the endosymbiotic microorganism from sponges and its effectiveness against marine ornamental fish pathogens. The sponges were collected from Agatti island of Lakshadweep archipelago and identified as Clathria procera, Sigmadocia fibulata and Dysidea granulosa. In which, 15 different types of bacteria were isolated and screened against marine ornamental fish pathogens (A. hydrophila, Vibrio alginolyticus, V. harveyii, V. parahaemolyticus and Pseudomonas fluorescens). The strain S25 was found as potential bacteria based on their antimicrobial activity against the fish pathogens. Molecular identification of the potential strain (S25) of the 16S rRNA gene showed 99% identity with Acinetobacter sp. The sequenced 16 s rRNA gene with 1,081 bp in length was submitted in NCBI Genbank and Accession was obtained (GenBank Accession number HM004071). The strain exhibited high similarity (99%) with the 16S rRNA gene of Acinetobacter calcoaceticus from GenBank database. Crude extract obtained with acetone and ethyl acetate from extracellular products of S25 showed significant antimicrobial activity by disc diffusion assay using 1,500 μg/ml of crude extract. Extracellular metobolite of A. calcoaceticus was extracted by shake flask method and the crude extract was partially purified by thin layer chromatography. Partially purified crude extract showed significant inhibition zone of antimicrobial activity (A. hydrophila, V. alginolyticus, V. parahaemolyticus) and less similar activity against V. harveyii and P. fluorescens. This is the first report on A. calcoaceticus isolated from sponges of Lakshadweep archipelago and the studies are underway to characterize and purify the antimicrobial compounds of the potential bacteria.

Antimicrobial activities of secondary metabolites and phylogenetic study of sponge endosymbiotic bacteria, Bacillus sp. at Agatti Island, Lakshadweep Archipelago

“…All the Twenty-one sponge samples were subjected to isolation of endosymbiotic bacteria followed by Gopi et al [18] . Using colony morphology different types of bacterial colonies were isolated and were repeatedly streaked to obtain pure cultures and stored in Zobell agar slants at 4 °C for further studies.…”

“…Using colony morphology different types of bacterial colonies were isolated and were repeatedly streaked to obtain pure cultures and stored in Zobell agar slants at 4 °C for further studies. Bacterial strains named as SEB 1 to SEB 113 and antibacterial activity was determined by using culture filtrate of sponge isolates against fish pathogens followed [18] such as Vibrio alginolyticus (FP1), Vibrio vulnificus (FP2), Vibrio parahaemolyticus (FP3), Aeromonas salmonicida (FP4), Flavobacterium sp. (FP5), Edwardsiella sp.…”

“…A seed culture of potential bacterial strain SEB32 was prepared in about 50 ml using Zobell marine broth [18] with pH-7.5, salinity-35 ppm (parts per million) in a shaker (30 °C/150 rpm) for 18 h. Inoculum was transferred to 500 ml Zobell marine broth containing 1 l Erlenmeyer flask and cultured with shaking (250 rpm) for 5–9 days at 28 °C. Cells were separated by centrifugation (4 °C/8671 g ).…”

Phylogenetic Investigations on the Endosymbiotic Bacteria of Axinella donnani

“…The earlier report by Dhinakaran et al showed that the sponge associated strain of Echinodictyum gorgonoides was tested for its antibacterial activity against various human pathogens (E. coli, Proteus Spp, S. aureus, Pseudomonas and B. subtilis) and Annie et al [26] reported the antibacterial activity of A. donnani against fish pathogens (Aeromonas against strains of MRSA and VRE [28]. In another study presence of phenolic compounds was confirmed by thin layer chroma-tography and associated Rf values of crude extract showed that the secondary metabolite was produced by endosymbiotic bacteria A. calcoaceticus in D. granulosa and was not from the sponge tissue [29]. Thus, the 2-(2, 4 -dibromophenoxy)-4,6-dibromo-phenol may be produced by the endosymbiotic bacteria of D. granulose.…”

Sponge-associated actinobacterial diversity: validation of the methods of actinobacterial DNA extraction and optimization of 16S rRNA gene amplification

“…They have attracted substantial research interests because of their ecological importance and their production of a wide range of bioactive compounds for pharmacological use (Ando et al 2010;Blunt et al 2010;Leal et al 2012;Sirirak et al 2013;Vogel 2008;Waters et al 2010). One striking characteristic of sponges is their association with a remarkable array of microorganisms, such as archaea (Preston et al 1996;Radax et al 2012;Turque et al 2010), bacteria (Hentschel et al 2001;Hentschel et al 2012;Montalvo and Hill 2011;Radwan et al 2010;Richardson et al 2012;Schmitt et al 2011;Webster and Hill 2001) including actinobacteria (Abdelmohsen et al 2014a) and cyanobacteria (Alex et al 2012;Thacker and Starnes 2003), unicellular algae (Annenkova et al 2011;He et al 2014;Hentschel et al 2012;Wecker et al 2015) and fungi (Gopi et al 2012;Maldonado et al 2005). These microorganisms are reported to comprise between 35 and 40 % of the total tissue volume in some sponge species Taylor et al 2007;Vacelet and Donadey 1977) and exceed a density of 10 9 microbial cells/ml of sponge tissue (de Voogd et al 2015;Webster and Hill 2001).…”