Isolation of microorganisms from vinasse and black liquor and screening of potential biosurfact.ant producers

RIVERO, MARIANO; IRAZUSTA, VERÓNICA PATRICIA; GUTIERREZ CACCIABUE, DOLORES; RAJAL, VERÓNICA BEATRIZ

Virtual

Congreso; CONGRESO SAIB-SAMIGE; 2020

Biosurfactants are compounds produced by microorganisms that have the ability to reduce interfacial tension. These biomolecules have advantages over their synthetic counterparts: they are biodegradable and don?t accumulate in the environment, they have a low level of toxicity and they have suitable physical and chemical properties for different applications. However, the downside is their higher production costs. The use of cheap substrates, some of them industrial by-products in whose composition are carbon sources, would be a viable option.The objectives of this work were: (1) to selectively isolate microorganisms capable of growing in media prepared with black liquor (alkaline) and vinasse (acid), from the paper industry and alcohol, respectively, and (2) evaluate the potential of production of biosurfactants from isolated strains that showed promise, by measuring surface tension (TS) by the modified pendant drop method.The selected substrates were two by-products from the production of paper and alcohol, respectively: black liquor and vinasse. A first isolation was carried out in prepared solid media (aqueous solution, substrate and agar), from which a total of 39 strains were obtained (19 from vinasse and 20 from black liquor).This was followed by two consecutive screening trials. For the first, tubes with 15 ml of medium (nutrient broth and 5% of the corresponding substrate) were inoculated with the 39 strains. For the second test, culture media with 5% and 20% proportions of each substrate were prepared and inoculated with preinoculars of selected strains from the first test, with an initial optical density established (OD600nm = 0.1). Both tests were performed in duplicate and with controls (sterile media without the addition of microorganisms) and the tubes were incubated at 35 ° C and 200 rpm. In the second trial, DO values were recorded.In both tests, the production of biosurfactants was evaluated by measuring TS by the pendant drop method (ADSA), performing simultaneous measurements with a multi-needle device developed for this purpose.Of the 39 strains evaluated, 15 strains were able to decrease TS compared to the control: 5 acidophilic (a1, a5, a6, a14 and a15) and 10 alkaliphilic (b1, b2, b3, b5, b6, b8, b10, b14, b17 and b20).In addition, of the 15 selected strains, 3 acidophilic strains (a1, a5 and a6) and 3 alkaliphilic (b1, b2 and b17), were able to appreciably decrease TS compared to the control (p