Editorial: Microbiotechnology Based Surfactants and Their Applications

This editorial is an annotation on the exciting research topic ‘Microbiotechnology based surfactants and their applications’ that covers a compilation of original research articles, reviews and mini-reviews submitted by researchers enthusiastically working in the field of biosurfactants. Biosurfactants, which for a long time have been confused with bioemulsifiers, derived their name from biologically produced surfactants. The term ‘Surfactants’ was, however coined by Antara products in 1950 – which covered all products having surface activity, including wetting agents, emulsifiers, dispersants, detergents and foaming agents. The terms biosurfactants and bioemulsifiers have been used interchangeably for a long time until a demarcation has been suggested by several researchers including Uzoigwe et al., 2015. They emphasized that although biosurfactants and bioemulsifiers are both amphiphilic in nature and produced by variety of microbes, there are marked differences between them in terms of their physico-chemical properties and physiological roles. Authors strongly presented their opinion that bioemulsifiers are not biosurfactants as only biosurfactants have the surfactant effect of reducing surface tension, although both can emulsify solutions. Debating on the topic of emulsification, another study by Das et al., 2014 from China, showed that emulsification potential and also the antimicrobial activity of rhamnolipid biosurfactants produced by crude oil extracted Pseudomonas sp. IMP67 is effected by the ratio of monorhamnolipid (MRL) and dirhamnolipid (DRL) congeners. The MRL and DRL congeners were analysed by thin layer chromatography and rhamnose quantification. Rhamnolipids from Pseudomonas sp. IMP67 also reduced the minimum inhibitory concentrations (MICs) of some antibiotics signifying the synergistic role of these rhamnolipids with antibiotics. If there is one major stumbling block in the flourishing of the business of biosurfactants it is their high cost of production. There are many factors that can play a significant role in order to bring down the expenses and make the process cost-effective. One such factor is the usage of low-cost substrates for the production of biosurfactants. Second to this could be the exploration of new strains or strains and classes which has been less-explored for biosurfactant production. An extensive review by Kugler and co-authors precisely talks about the class Actinobacteria and suggest a lack of structural information on a large proportion of Actinobacterial surfactants. Authors claim that the sheer magnitude of Actinobacterial surfactants that still remains undetermined is evident from this comprehensive review (Kugler et al., 2015). A better understanding of the diversity of the Actinobacterial surfactants would allow to further explore their potential for various novel biotechnological applications just as in case of lipopeptide biosurfactants produced by many microorganisms including Bacillus species. Lipopeptides, a series of chemical structural analogues of many different families, are one of the five major classes of biosurfactants known. Among the different families identified, 26 families covering about 90 lipopeptide compounds have been reported in last two decades (Liu et al., 2015). Not only the less-researched strains and classes but a significant leap is required investigating the carbon sources that would work best for high biosurfactant production. Addressing this area are the original research articles by Antoniou et al., 2015, Gudina et al., 2015, and Ismail et al., 2014, and a review by Banat et al., 2014. Eleftheria Antoniou and co-researchers from Greece, investigated the biosurfactant production yield of marine hydrocarbon degraders isolated from Elefsina Bay (Eastern Mediterranean Sea) in presence of heavy oil fraction of crude oil as substrate. Their data particularly emphasized on Paracoccus marcusii to be an optimal choice for various bioremediation applicatio