Inhibition of marine biofouling by aquatic Actinobacteria and coral-associated marine bacteria

Aims: Biofouling is a common biology phenomenon occuring on ship surface. This phenomenon has become serious threat in marine industries because of great economic loss. Tributyltin has been used to prevent biofouling, but it turned to cause the environmental problem. Therefore, the discovery of alternative environment-friendly compound is necessarily needed. Methodology and results: Five Actinobacteria isolates and fourteen marine bacteria isolates were tested against the biofilm formation of eight biofouling bacteria isolates that isolated from boat surface and the attachment of three biofouling diatoms (Amphora, Navicula, Nitzschia). Actinobacteria CW17 supernatant showed the broad spectrum activity against all fouling bacteria, whereas BC 11-5 supernatant was the only marine bacteria that capable to inhibit biofilm formation of V. neocaledonicus. Moreover, three representative diatoms attachment could be inhibited by the bioactive compounds produced by Actinobacteria and marine bacteria. CW01 supernatant showed broad spectrum and high activity against all three representative diatoms which is very promising. Molecular identification based on 16S rDNA gene sequence showed eight fouling bacteria isolates were biofilm-forming bacteria. Conclusions, significance and impact of study: This research showed aquatic Actinobacteria and coral-associated marine bacteria have the potential to prevent biofouling formation. Further studies are needed to purify and characterize these antibiofouling compounds for environmental application.

Characterization of bioactive compound from actinomycetes for antibiofilm activity against Gram-negative and Gram-positive bacteria

Aims: Biofilm is an assemblage of microorganisms enclosed in a matrix of extracellular materials, such as, extracellular polysaccharide (EPS), and relates to bacterial virulence, pathogenesis, and environmental survival. Bacteria inside biofilm are more resistant to conventional antibiotics and the host immune system. Non-biocidal antibiofilm compounds have been developed to address this problem. Specifically, actinomycetes have known to produce many metabolite compounds that have useful application in medicine and biotechnology. The study aimed to characterize bioactive compounds from actinomycetes crude extract that have capability as a multispecies antibiofilm agent. Methodology and results: In this study, none of the isolates had shown any antimicrobial activity. Based on the antibiofilm assay, most of the isolates have the capability to inhibit and to destroy biofilm formation of pathogenic bacteria at a 5% and 10% dosage. The crude extracts showing the highest activity for antibiofilm inhibition were extracted from Streptomyces sp. The characterization of the bioactive compounds showed that different components of a particular isolate responsible for its antibiofilm activity against pathogenic bacteria. The SW19 isolate had a nucleic acid, KP12 isolate had a combination of the three component (polysaccharide, protein, and nucleic acid), and CW17 isolate had a combination of polysaccharide and nucleic acid as the active compound for antibiofilm activity. Conclusion, significance and impact study: Thus, the bioactive crude extracts from actinomycetes has high potential to be used in treating biofilm-related infection and further research is needed to purify the bioactive compound from the crude extract which has antibiofilm activity against Gram-positive and Gram-negative pathogens.