Abstract
Seaweeds of the intertidal regions are a rich source of surface associated bacteria and are potential source of antimicrobial molecules. In the present study, 77 epiphytic isolates from eight different algae collected from Little Andaman were enumerated. On testing for their antimicrobial activities against certain pathogens twelve isolates showed positive and six of them showed significant antimicrobial inhibition zone against Shigella boydii type 1, Shigella flexneri type 2a, Shigella dysenteriae type 5, Enterotoxigenic Escherichia coli O115, Enteropathogenic E. coli serotype O114, Vibrio cholera; O1 Ogawa, Aeromonas hydrophila, Klebsiella pneumoniae, Staphylococcus aureus. Based on the activity these six isolates (G1C, G2C, G3C, UK, UVAD, and Tor1) were identified by 16S rRNA gene sequence and were found to belong to the phyla Firmicutes and Proteobacteria. Purified antimicrobial compounds obtained from these isolates were identified by GC-MS. Furan derivatives were identified from G2C Pseudomonas stutzeri KJ849834, UVAD Alcanivorax dieselolei KJ849833, UK Vibrio sp. KJ849837, Tor1 Exiguobacterium profundum KJ849838. While 2-Pyrrolidinone, Phenol, 2, 4-bis (1, 1-dimethylethyl) were from G3C Vibrio owensii KJ849836 and (1-Allylcyclopropyl) methanol from the extracts of G1C Bacillus sp. KJ849835. The results of the present study shows that these six potent isolates isolated from the seaweeds are found to be a source of antimicrobial compounds.
Highlights
Marine eukaryotes such as seaweeds are one of the primary producers which offers nutrient rich environment for microbial communities (Egan et al, 2008; Wahl, 2008)
All the seventy seven cultivable epiphytic bacterial isolates obtained from the thallus of eight different seaweeds were plated on Marine agar
The Isolate UVAD was identified as Alcanivorax dieselolei with 99% similarity and Torl strain was identified with 99.7% similarity as Exiguobacterium profundum (Figure 1)
Summary
Marine eukaryotes such as seaweeds are one of the primary producers which offers nutrient rich environment for microbial communities (Egan et al, 2008; Wahl, 2008). Surface associated marine organisms such as bacteria, fungi, diatoms, larval forms of marine invertebrate’s have been reported to be associated with the thallus of seaweeds (Goecke et al, 2010; Burke et al, 2011; Murthy et al, 2016; Karthick and Mohan, 2017). Such host association epiphytic bacteria are sources of certain natural compounds (Singh et al, 2011; Ali et al, 2012; Martin et al, 2014). Importance of microbial diversity of seaweeds, bacterial genus are highly host specific with novel species, which have emerged from these algal environment (Goecke et al, 2013).
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