Antibiofilm activity of secondary metabolites from bacterial endophytes of Red Sea soft corals

Endophytic marine bacteria are a significant unexplored resource for the search of new compounds with anti-fouling activity. In this study, endophytic marine bacteria isolated from Red Sea soft corals were subjected to secondary metabolites extraction and evaluation of the extracts for the antibiofilm activity to reveal compounds that can prevent biofilm bacterial colonization on surfaces. Six bacteria were isolated from two species of soft corals: Sarcophyton glaucum and Heteroxenia fuscescens. Extracts obtained from each strain were screened for antibiofilm activity against three biofilm-forming bacteria and evaluated to detect compounds with antibiofilm properties by Gas chromatography-mass spectrometry (GC-MS). The isolated strains are closely related and belong to the family Bacillaceae and all except one belong to the Bacillus genus. The extracts from the endophytes show significant antibacterial activity against the tested organisms. Biofilm formation inhibition activity of the extracts ranges from 3.16 to 98.41%. The extracts also showed significant activity against biofilm formation across all the tested strains. Compounds detected in the extracts include known compounds with antibiofilm properties such as 2,4-dimethyl-2-nitro-, 2,4-bis(1,1-dimethylethyl)-phenol, Pyrrolo[1,2-a] pyrazine-1,4-dione, hexahydro-3-(2-methylpropyl)-; Bis(tridecyl) phthalate, Heinecosane, Pentane, and Undecane.This indicates the ability of the bacteria to produce compounds relevant in preventing biofilm colonization on surfaces which could serve as a novel source of antifouling compounds.