Sophorolipid production by yeasts: a critical review of the literature and suggestions for future research

Abstract

Sophorolipids are well-known biosurfactants produced by yeasts, having potential applications ranging from nanomaterials, medicine, and cosmetics to large-volume applications such as cleaning and soil remediation. Because of their environmentally friendly nature, they attained much interest during the past decades as a sustainable and ecological alternative to petroleum-derived surfactants. Stronger yet, research activities and scientific publications on the topic are ever increasing. However, often these studies lack proper producer strain identification and detailed structural product characterization. Flaws regarding strain identity can have huge consequences when moving to valorization and moreover tend to persist quite long in scientific literature. Furthermore, too often sophorolipid production is proposed where other biosurfactant structures cannot be ruled out based on the chemical analysis. Finally, absolute quantitative yield determination frequently occurs with variable product purity and without proper calibration standards. This review aims to highlight and discuss these discrepancies and proposes some guidelines for good practice in future sophorolipid research.

Improvement of biosurfactant production by Wickerhamomyces anomalus CCMA 0358 and its potential application in bioremediation

“…Regarding the effect of pH, the biosurfactant produced by W. anomalus CCMA 0358 was more stable under neutral and alkaline conditions (pH [6][7][8][9][10][11][12], where the surface tension remained almost constant ( Table 5). On the contrary, at acidic pH values, a slight increase in the surface tension values was observed, meaning that the biosurfactant was less active in those conditions.…”

“…Most of the traditional chemical surfactants commonly used are obtained from petrochemical resources, and exhibit high toxicity and low biodegradability [9,10]. Given the increasing concern regarding the environmental hazard of synthetic surfactants, and in order to address the growing demand for eco-friendly alternatives, research focusing on the production of bio-based surfactants has increased in the past few years [11]. The market for these "green" alternatives to the traditional chemical surfactants is expected to increase up to USD 2800 million by 2023, with a worldwide production around 462 kilo tons per year [12].…”

“…Among the bio-based surfactants, biosurfactants, a heterogeneous group of surface-active compounds synthesized by different microorganisms, have emerged as promising alternatives to the synthetic surfactants. In the past 10 years, biosurfactants have received pronounced attention owing to their excellent interfacial activities, low toxicity, high biodegradability, and stability under extreme conditions of temperature, pH and salinity [4,8,11,13]. As a result of these properties, biosurfactants could replace chemical surfactants in many industrial applications [14][15][16][17][18].…”

Klinik ve Çevresel Exophiala İzolatlarında Biyosurfaktan Üretiminin Karşılaştırılması

“…Biyosurfaktan varlığı araştırmalarında genel olarak benzer sorunlar tespit edilmektedir. Güncel literatürde biyosurfaktan varlığını araştıran yayınlar giderek artmaktadır 1,10,11 . Ancak bu çalışmaların çoğunda karşılaşılan problemler; biyosurfaktan üreten mikroorganizmanın tanımlanmaması, biyosurfaktanın yetersiz karakterizasyonu ve yetersiz metodolojiden kaynaklanan güvensizliktir 10,11 .…”

Starmerella bombicola: recent advances on sophorolipid production and prospects of waste stream utilization

“…Indeed, the example of Wickerhamiella domercqiae var. sophorolipid (also referred to as W. domercqiae Y2a, CGMCC1576 and CGMCC3798), which was revealed to be an S. bombicola strain after whole genome sequencing, proves the importance of proper strain identification based on molecular techniques . The authors suggest proper strain identity confirmation of this C. albicans species by molecular techniques (e.g.…”