Commonly-used screening techniques for determination of biosurfactants production by microorganisms include haemolysis assay, generally depicted to confirm the ability of microorganisms in production of biosurfactants. Diameters of zones of haemolysis surrounding microbial colonies are considered as quantitative indication of biosurfactant production whereas; haemolytic reactions on blood agar plates are specifically associated with pathologic types of erythrocyte lysis by microorganisms, due to haemolysins production. Haemolytic microorganisms can destroy erythrocyte membranes, by compromise in integrity of cytoplasmic membranes, through pore-forming mechanisms, multiple-hit mechanism, formation of sphaerocytes, derangement of membrane integrity, detergentlike action, or lipase activity. Relative levels of acute toxicity, cell invasiveness and virulence factors, which can make biosurfactants become opportunistic pathogens that use haemin or haemoglobin as a source of iron, have also been reported. Haemolysins are further classically defined as exotoxins that can be thermostable, and can cross membranes of microorganisms. Haemolysis assay thus, identifies haemolytic microbial strains with lytic, pathogenic, toxigenic, and/or virulent potentials, rather than biosurfactant-producing potential, as the assay does not correlate particularly with specific characteristics of biosurfactants’ production. However, based on new insights and perspectives appropriately extrapolated for the first time in this report, microbial haemolysis assay is considered, the easiest, most-economical, non-animal-based, highly-determinative, reliable and sensitive biosafety selection criterion protocol, for selection of safe and environmental-friendly biosurfactant candidates, for the petroleum industries’ process conditions.
Published Date: 2021-09-21; Received Date: 2021-07-10