The true methodology for rhamnolipid: Various solvents affect rhamnolipid characteristics

Abstract

Rhamnolipid, among the most effective biosurfactants, is a glycolipid‐type biosurfactant primarily produced by Pseudomonas aeruginosa. In this study, rhamnolipid production was carried out using a strain of P. aeruginosa and it is aimed to compare rhamnolipid biopolymers obtained from various extraction methods using glycine (RG), hydrochloric acid (RH), diethyl ether (RD), ethyl acetate (RE). Comparison analyses were performed through NMR, FTIR techniques and viscosity, density measurements apart from determination of rhamnolipid yields. It can be concluded that rhamnolipid from diethyl ether for extraction is far from molecular structure to reference rhamnolipid molecule according to instrumental analyses performed. Besides, the yield of this rhamnolipid is much more than other rhamnolipids extracted through other methods but this is misleading because the value in there may be total sugar content apart from rhamnolipid. Therefore, RD extraction method can be said to be non‐selective process for rhamnolipid obtained. In RH method, some functional group peaks belonging to rhamnolipid were not observed. NMR analysis showed that some CH groups were not observed in the RG method. However, especially NMR and FTIR analyses showed that rhamnolipid obtained from RE method represented more accurate rhamnolipid based on reference molecule. Practical applications: This study showed that rhamnolipid production and its comparative analyses using various solvent extraction methods. Comparison analyses were carried out through NMR, FTIR techniques and viscosity, density measurements as well as determination of rhamnolipid yields. Different solvents affect seriously characteristics of rhamnolipid, which were defined in the previous literature reports. Especially, some methods are not selective ways for mentioning true biomolecule. To avoid misleading characterization information in the literature, these extraction methods were discussed through comparison methods such as NMR, FTIR analyses, and quantification measurements. Rhamnolipid biopolymers obtained from various extraction methods using glycine (RG), hydrochloric acid (RH), diethyl ether (RD), ethyl acetate (RE) are compared through NMR, FTIR techniques, and viscosity, density measurements. These analyses show that rhamnolipid obtained from RE method represents more accurate rhamnolipid based on reference molecule.

Adaptive evolution of Methylotuvimicrobium alcaliphilum to grow in the presence of rhamnolipids improves fatty acid and rhamnolipid production from CH4

“…The UHPLC method used was as described (Baidoo et al, 2019 ; Kim et al, 2021 ). For RL analysis, the cell pellets and supernatants were processed using an acidic (HCl) methanol/chloroform precipitation method described previously (Çakmak et al, 2017 ).…”

Microbial biosurfactant research: time to improve the rigour in the reporting of synthesis, functional characterization and process development

“…Such methods are widely applied for both glycolipid type biosurfactants and high molecular weight bioemulsifier type compounds (Kourmentza et al ., 2019; Naughton et al ., 2019; Roelants et al ., 2019). When performing biosurfactant purification via liquid‐phase extraction followed by evaporation of the solvent or by precipitation of the compounds from broth or supernatant the end point is often an oily, honey‐like product (Roelants et al ., 2016; Çakmak et al ., 2017). These oily products typically also still contain up to 60 % water, which is mostly not determined and/or reported and thus results in an overestimation of the reported production.…”

Biosurfactants’ Potential Role in Combating COVID-19 and Similar Future Microbial Threats

“…Their hydrophilic moieties can be made of acid, cationic peptide, anion, sugar (monosaccharide, disaccharide, or polysaccharide) and hydrophobic moieties made of hydrocarbon or fatty acid chains. They are environmentally friendly and have been shown to have many industrial applications sometimes performing better than synthetic surfactants [3][4][5][6][7]. Their physico-chemical properties include; high stability in a wide range of environmental conditions such as extreme pH, temperature and also salt concentration [8,9], high biodegradability with a high rate of mineralization by soil microcosms [10], low toxicity, surface tension reduction, foaming capacity and antimicrobial activity against pathogens [11][12][13][14].…”