Production and characterization of biosurfactants produced by microorganisms isolated from milk factory wastewaters

Biosurfactants production by marine yeasts isolated from zoanthids and characterization of an emulsifier produced by Yarrowia lipolytica LMS 24B

The present study investigates the potential for biosurfactant production of 19 marine yeast species obtained from zoanthids. Using the emulsification index test to screen the samples produced by the marine yeasts, we verified that five isolates exhibited an emulsification index ≥50%. Additional tests were performed on such isolates, including oil displacement, drop collapse, Parafilm M assay, and surface tension measurement. The tolerance of produced biosurfactants for environmental conditions was also analyzed, especially considering the media's temperature, pH, and salinity. Moreover, the surfactant's ability to emulsify different hydrocarbon sources and to metabolize kerosene as the sole carbon source was evaluated in vitro. Our results demonstrate that yeast biosurfactants can emulsify hydrocarbon sources under different physicochemical conditions and metabolize kerosene as a carbon source. Considering the Yarrowia lipolytica LMS 24B as the yeast model for biosurfactant production from the cell's wall biomass, emulsification indexes of 61.2% were obtained, even at a high temperature of 120 °C. Furthermore, the Fourier-transform middle infrared spectroscopy (FTIR) analysis of the biosurfactant's chemical composition revealed the presence of distinct functional groups assigned to a glycoprotein complex. Considering the status of developing new bioproducts and bioprocesses nowadays, our findings bring a new perspective to biosurfactant production by marine yeasts, especially Y. lipolytica LMS 24B. In particular, the presented results validate the relevance of marine environments as valuable sources of genetic resources, i.e., yeast strains capable of metabolizing and emulsifying petroleum derivatives.

A comprehensive review on production of bio-surfactants by bio-degradation of waste carbohydrate feedstocks: an approach towards sustainable development

The advancement of science and technology demands chemistry which is safer, smarter and green by nature. The sustainability of science thus requires well-behaved alternates that best suit the demand. Bio-surfactants are surface active compounds, established to affect surface chemistry. In general, microbial bio-surfactants are a group of structurally diverse molecules produced by different microbes. A large number of bio-surfactants are produced during hydrocarbon degradation by hydrocarbonoclistic microorganisms during their own growth on carbohydrates and the production rate is influenced by the rate of degradation of carbohydrates. The production of such biological surfactants is thus of greater importance. This write up is a dedicated review to update the existing knowledge of inexpensive carbohydrate sources as substrates, microorganisms and technologies of biosurfactant production. This is an economy friendly as well as sustainable approach which will facilitate achieving some sustainable development goals. The production is dependent on the fermentation strategies, different factors of the microbial culture broth and downstream processing; these all have been elaborately presented in this article.

Bioremediation of Wastewater Using Yeast Strains: An Assessment of Contaminant Removal Efficiency

The main goal of wastewater treatment is to significantly reduce organic compounds, micronutrients (nitrogen and phosphorus) and heavy metals and other contaminants (pathogens, pharmaceuticals and industrial chemicals). In this work, the efficiency of removing different contaminants (COD, NO₃^-, NO₂^-, NH₄⁺, PO₄^3-, SO₄^2-, Pb²⁺, Cd²⁺) from synthetic wastewater was tested using five different yeast strains: Kluyveromyces marxianus CMGBP16 (P1), Saccharomyces cerevisiae S228C (P2), Saccharomyces cerevisiae CM6B70 (P3), Saccharomyces cerevisiae CMGB234 (P4) and Pichia anomala CMGB88 (P5). The results showed a removal efficiency of up to 70% of COD, 97% of nitrate, 80% of nitrite, 93% of phosphate and 70% of sulfate ions for synthetic wastewater contaminated with Pb²⁺ (43 mg/L) and Cd²⁺ ions (39 mg/L). In contrast, the results showed an increase in ammonium ions, especially in the presence of Pb²⁺ ions. The yeast strains showed a high capacity to reduce Pb²⁺ (up to 96%) and Cd²⁺ (up to 40%) ions compared to the initial concentrations. In presence of a crude biosurfactant, the removal efficiency increased up to 99% for Pb²⁺ and 56% for Cd²⁺ simultaneously with an increase in yeast biomass of up to 11 times. The results, which were obtained in the absence of aeration and in neutral pH conditions, proved a high potential for practical applications in the biotreatment of the wastewater and the recovery of Pb and Cd ions, with a high benefit-cost ratio.

Production of rhamnolipids by the Thermoanaerobacter sp. CM-CNRG TB177 strain isolated from an oil well in Mexico

This study aimed to produce and characterize biosurfactants using the Thermoanaerobacter sp. CM-CNRG TB177 strain isolated from an oil field in Mexico, as well as assessing the influence of different carbon and nitrogen sources on the capacity of the produced surfactant to reduce the surface tension of water. The thin-layer chromatography (TLC) revealed that the obtained extract corresponds to a mono-rhamnolipid; the results of the ultra-performance-liquid chromatography/mass spectrometry (UPLC/MS) analysis revealed that the Thermoanaerobacter sp. CM-CNRG TB177 strain produces a mixture of three rhamnolipids, whose masses correspond to mono-rhamnolipid. The rhamnolipids mixture obtained using 2.5% molasses as carbon source diminished the surface tension of water to 29.67 mNm^-1, indicating that the concentration of molasses influenced the capacity of the produced surfactant to reduce the surface tension of water. Also, the microorganism was not capable of growing in the absence of yeast extract as nitrogen source. To the best of our knowledge, the presented results describe for the first time the nature of the biosurfactant produced by a bacterium of the Thermoanaerobacter genus.Key points• Thermoanaerobacter sp. CM-CNRG TB177 produces biosurfactants, and its glycolipid nature is described for the first time.• The HPLC analysis revealed a mixture of three rhamnolipid congeners, and UPLC/MS analysis determined that two of the congeners are the rhamnolipids Rha-C8-C10 and Rha-C12-C10.• The lowest surface tension of 29.67 mNm^-1 was obtained with molasses as source of carbon at a 2.5% concentration.

Microbial production of rhamnolipids using sugars as carbon sources

Rhamnolipids are a class of biosurfactants with effective surface-active properties. The high cost of microbial production of rhamnolipids largely affects their commercial applications. To reduce the production post, research has been carried out in screening more powerful strains, engineering microbes with higher biosurfactant yields and exploring cheaper substrates to reduce the production cost. Extensive refining is required for biosurfactant production using oils and oil-containing wastes, necessitating the use of complex and expensive biosurfactant recovery methods such as extraction with solvents or acid precipitation. As raw materials normally can account for 10-30% of the overall production cost, sugars have been proven to be an alternative carbon source for microbial production of rhamnolipids due to its lower costs and straightforward processing techniques. Studies have thus been focused on using tropical agroindustrial crop residues as renewable substrates. Herein, we reviewed studies that are using sugar-containing substrates as carbon sources for producing rhamnolipids. We speculate that sugars derived from agricultural wastes rich in cellulose and sugar-containing wastes are potential carbon sources in fermentation while challenges still remain in large scales.

Biosynthesis, characterization and potentiality of lipopeptides produced by Bacillus flexus S1 without inductive carbon sources

This study newly isolated a bacterial stain ofBacillus flexusS1 which had abilities of synthesizing lipopeptides without any inductive operations, and thus it could effectively save operational procedures or cost.

Yarrowia lipolytica and pollutants: Interactions and applications

Yarrowia lipolytica is a dimorphic, non-pathogenic, ascomycetous yeast species with distinctive physiological features and biochemical characteristics that are significant in environment-related matters. Strains naturally present in soils, sea water, sediments and waste waters have inherent abilities to degrade hydrocarbons such as alkanes (short and medium chain) and aromatic compounds (biphenyl and dibenzofuran). With the application of slow release fertilizers, design of immobilization techniques and development of microbial consortia, scale-up studies and in situ applications have been possible. In general, hydrocarbon uptake in this yeast is mediated by attachment to large droplets (via hydrophobic cell surfaces) or is aided by surfactants and emulsifiers. Subsequently, the internalized hydrocarbons are degraded by relevant enzymes innately present in the yeast. Some wild-type or recombinant strains also detoxify nitroaromatic (2,4,6-trinitrotoluene), halogenated (chlorinated and brominated hydrocarbons) and organophosphate (methyl parathion) compounds. The yeast can tolerate some metals and detoxify them via different biomolecules. The biomass (unmodified, in combination with sludge, magnetically-modified and in the biofilm form) has been employed in the biosorption of hexavalent chromium ions from aqueous solutions. Yeast cells have also been applied in protocols related to nanoparticle synthesis. The treatment of oily and solid wastes with this yeast reduces chemical oxygen demand or value-added products (single cell oil, single cell protein, surfactants, organic acids and polyalcohols) are obtained. On account of all these features, the microorganism has established a place for itself and is of considerable value in environment-related applications.

Food-related applications of Yarrowia lipolytica

Yarrowia lipolytica is a non-pathogenic generally regarded as safe yeast. It displays unique physiological as well as biochemical properties that are relevant in food-related applications. Strains naturally associated with meat and dairy products contribute towards specific textures and flavours. On some occasions they cause food spoilage. They produce food-additives such as aroma compounds, organic acids, polyalcohols, emulsifiers and surfactants. The yeast biomass has been projected as single cell oil and single cell protein. Y. lipolytica degrades or upgrades different types of food wastes and in some cases, value-added products have also been obtained. The yeast is thus involved in the manufacture of food stuffs, making of food ingredients, generation of biomass that can be used as food or feed and in the effective treatment of food wastes. On account of all these features, this versatile yeast is of considerable significance in food-related applications.