Table 1.

Summary of biosurfactant types based on their molecular weight, origin and industrial application. Wherever possible a schematic of the chemical structure is provided.

Biosurfactant type	Origin	Chemical structure	Industrial application	References
Low-molecular weight biosurfactants
Glycolipids
Rhamnolipid	Pseudomonas aeruginosa Burkholderia thailandensis Marinobacter sp. strain MCTG107b	Rhamnose monosaccharide/s linked to 3-hydroxyl fatty acid unit via ß-glycosidic bond	Bioremediation Agriculture Cosmetics Pharmaceuticals Marine oil spills	Funston et al., 2016; Chong and Li, 2017; Twigg et al., 2018; Tripathi et al., 2019
Sophorolipid	Candida spp.	Dimeric sugar sophorose head linked to a long chain hydroxy fatty acid tail	Cosmetics Personal care products	Van Bogaert et al., 2007; Kurtzman et al., 2010; Santos et al., 2017
Trehalose lipids	Rhodococcus erythropolis	Trehalose sugar linked to long chain fatty acids (C20 to C90)		Peng et al., 2007
Mannosylerythrol lipids (MELs)	Candida antarctica Pseudozyma spp.	Long-chain fatty acids linked to a mannopyranosyl-meso-erythritol hydrophilic head group	Food	Adamczak and Bednarski, 2000; Morita et al., 2013; Niu et al., 2019
Lipopeptides
Surfactin, iturin and fengycin	Bacillus subtilis	Cyclic lipopeptide consisting of long hydroxyl fatty acid chain and hydrophobic amino acid ring	Soil bioremediation MEOR	Vanittanakom et al., 1986; Al-Wahaibi et al., 2014; Inès and Dhouha, 2015; Liu et al., 2015
Lichenysin	Bacillus lichenformis	Cyclic lipopeptide similar to surfactin	MEOR	Yakimov et al., 1995; Joshi et al., 2015; Coronel-León et al., 2016
Viscosin	Pseudomonas fluorescens	Cyclic lipopeptide similar to surfactin	Agriculture	Laycock et al., 1991; De Bruijn and Raaijmakers, 2009
High-molecular weight bioemulsifiers
Emulsan	Acinetobacter calcoaceticus RAG-1	A complex of a lipoheteropolysaccharide (apoemulsan) and a protein	MEOR	Rosenberg and Ron, 1999; Uzoigwe et al., 2015
Alasan	Acinetobacter radioresistens KA53	A complex of anionic polysaccharides rich in alanine and proteins with high molecular mass	Bioremediation MEOR	Navon-Venezia et al., 1995; Toren et al., 2001
Liposan	Candida lipolytica	A complex of heterpolysaccharides and protein	Pharmaceuticals Food Cosmetics	Cirigliano and Carman, 1985; Campos et al., 2013
Sphingan	Sphingomonas spp.	Linear tetrasaccharide backbone (glucose-glucoronic acid-glucose-rhamnose/mannose) to which glucosyl, rhamnosyl, mannosyl or acetyl side chains are attached	Food Textile Pharmaceuticals Oil and Gas	Schultheis et al., 2008; Prajapati et al., 2013; Kaur et al., 2014; Li et al., 2016
Xanthan gum	Xanthomonas campestris	A backbone of repeating sub-units of 3 to 8 monosaccharides	Food Oil and Gas	Kuppuswami, 2014; de Mello Luvielmo et al., 2016; Kang et al., 2019