| Summary: | Background. The important problem of biosurfactants production is biosynthesis optimization. But lack of effective isolation methods elaboration with simultaneous new costeffective products is the greatest weaknesses of existing technologies.
Objective. The aim of the study is rational technology elaboration for isolation of biosurfactants obtained from strains Pseudomonas sp. PS-17 and P. fluorescens 8573. Investigation of the influence of different acids and temperatures on the efficiency of isolation of the surfactant products, study the properties of the obtained products. Determination of the possible directions of the use of supernatant obtained after precipitation of the biocomplexes (SPL) as a new inexpensive product.
Methods. Rhamnolipid surfactant concentrate was precipitated from culture liquid supernatant (CLS) by acidification to pH 3-4 with acid solutions (HCl, H2SO4, H3PO4, HNO3, CH3COOH), kept at 100 °C for 25 min, cooled to room temperature, centrifuged before the phase separation, the supernatant was decanted. The surface tension of the SPL was determined by du Noüy method (with a platinum ring). The emulsification index of biosurfactants was determined regarding mineral oil and sunflower oil. The RLs were isolated from the SPL by extraction with a mixture of ethyl acetate and isopropanol, their composition was determined by thin layer chromatography. Influence on plants was assessed by their morphometric parameters after presowing seed treatment.
Results. The rational technology for surfactants isolation from strains Pseudomonas sp. PS-17 and P. fluorescens 8573 was developed It was shown that the suitable method of the isolation of the biosurfactants of Pseudomonas sp. PS-17 and P. fluorescens 8573 is acidic precipitation from CLS with heating. As a result, the product yield was increased by 20%, and the duration of the process was reduced. The physico-chemical properties of the SPLs after the isolation of biosurfactants from the CLS were studied. SPLs have been shown to be effective oil emulsifiers, foaming and wetting agents for various surfaces. It was shown that SPLs (at dilutions 1:10) do not exhibit phytotoxic effects and stimulate the growth of watercress.
Conclusions. The new wasteless technology for Pseudomonas strains biosurfactants isolation has been proposed, which provides for the elimination of the extraction stage with solvents, as a result, the yield of the target products has been increased. Thus, the technology has economic and environmental advantages. It was shown that SPLs, being inexpensive and effective products, can be used in environmentally friendly technologies: in agriculture (for stimulation of plant growth), for remеdiation of contaminated soils, production of detergent compositions.
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