During 2020, the world has experienced extreme vulnerability in the face of a disease outbreak. The coronavirus disease 2019 (COVID-19) pandemic discovered in China and rapidly spread across the globe, infecting millions, causing hundreds of thousands of deaths, and severe downturns in the economies of countries worldwide. Biosurfactants can play a significant role in the prevention, control and treatment of diseases caused by these pathogenic agents through various therapeutic, pharmaceutical, environmental and hygiene approaches. Biosurfactants have the potential to inhibit microbial species with virulent intrinsic characteristics capable of developing diseases with high morbidity and mortality, as well as interrupting their spread through environmental and hygiene interventions. This is possible due to their antimicrobial activity, ability to interact with cells forming micelles and to interact with the immune system, and compatibility with relevant processes such as nanoparticle synthesis. They, therefore, can be applied in developing innovative and more effective pharmaceutical, therapeutics, sustainable and friendly environmental management approaches, less toxic formulations, and more efficient cleaning agents. These approaches can be easily integrated into relevant product development pipelines and implemented as measures for combating and managing pandemics. This review examines the potential approaches of biosurfactants as useful molecules in fighting microbial pathogens both known and previously unknown, such as COVID-19.

In the present study, culture conditions of Streptococcus equi was optimized through Box-Behnken experimental design for hyaluronic acid production. About 0.87 gL of hyaluronic acid was produced under the determined conditions and optimal conditions were found as 38.42 °C, 24 hr and 250 rpm. The validity and practicability of this statistical optimization strategy were confirmed relation between predicted and experimental values. The hyaluronic acid obtained under optimal conditions was characterized. The effects of different conditions such as ultraviolet light, temperature and enzymatic degradation on hyaluronic acid produced under optimal conditions were determined. 118 °C for 32 min of autoclaved HA sample included 63.09 µg mL of d-glucuronic acid, which is about two-fold of enzymatic effect. Cytotoxicity of hyaluronic acid on human dermal cells (HUVEC, HaCaT), L929 and THP-1 cells was studied. In vitro effect on pro or anti-inflammatory cytokine release of THP-1 cells was determined. Although it varies depending on the concentration, cytotoxicity of hyaluronic acid is between 5 and 30%. However, it varies depending on the concentration of hyaluronic acid, TNF-α release was not much increased compared to control study. Consequently, purification procedure is necessary to develop and it is worth developing the bacterial hyaluronic acid.

BACKGROUND In this study, hyaluronic acid (HA) was produced using Streptococcus equi ssp. equi via an optimized Central Composite Design process, with purification by an alternative extraction method. Determinations of molecular weight, cytotoxicity, viscosity; proton nuclear magnetic resonance (H‐NMR) and Fourier transform infrared‐attenuated total reflection (FTIR‐ATR) analyses were provided. RESULTS The HA yield obtained was up to c. 12 g L−1 under the reaction conditions of pH 7.8, 33 °C incubation temperature, 24 h incubation time and 187 rpm agitation rate. According to gel permeation chromatography results, HA has an average molecular weight of 79 416 Da. FTIR‐ATR analysis showed that the spectrum of the standard HA sample overlapped with the spectrum obtained from this study. CONCLUSION In this study, higher titer production of HA was obtained with a simple and economical sequential process. Additionally, the results indicate that the HA produced is an appropriate biomaterial for medical applications. © 2019 Society of Chemical Industry

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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.