Biological surfactants are amphipathic molecules produced by microorganisms and are considered multifunctional compounds of the 21st century. The current work aimed to use low-cost renewable substrates for economic production of biosurfactant by Issatchenkia orientalis UCP 1603. Fermentations were carried out at 28°C and 150 rpm for 72 h, using agro-industrial by-products (cassava wastewater, corn steep liquor and post-frying soybean oil) as substrates, according to a 23 full-factorial design (FFD) to identify their influence on biosurfactant production. The results showed the ability of the yeast to produce biosurfactant in all conditions of FFD, standing out the condition 4 due to the greatest reduction of surface tension (from 72 to 29.7 mN/m). The statistical analyses evidenced the significative influence of cassava wastewater and corn steep liquor on biosurfactant production. The tensoactive properties of the biomolecule were confirmed by parafilm test and emulsification index. This study evidenced I. orientalis as promising biosurfactant-producing yeast, with excellent ability and higher biotechnological potential for transformation of agro-industrial by-products.

Microbial surfactants are amphiphilic molecules with attractive industrial prospects due to their advantages over commonly commercialized chemical surfactants, such as low toxicity, high biocompatibility and biodegradability, and efficiency at extreme conditions. However, the large-scale production of biosurfactants still becomes uncompetitive due to the low yields and onerous costs, being considered the use of renewable substrates as a viable strategy. In this sense, the present study aimed to investigate the sustainable production of biosurfactant by the yeast Issatchenkia orientalis UCP 1603 in 2 L of salt-based medium supplemented with 7.5% cassava wastewater, 5% corn steep liquor and 1% post-frying soybean oil. Fermentation was carried out in 2.8 L-Fernbach flasks for 72 h, at 28°C and 150 rpm, and reduction in surface tension to 30.1 mN/m was verified. The highest yield of the biosurfactant produced (4.02 g/L) was observed after extraction with 70% ethanol (2:1, v/v) and the isolated biosurfactant reduced the surface tension of the medium to 28.7 mN/m, the interfacial tension against n-hexadecane to 16.6 mN/m and has a CMC of 800 mg/L. The biocompound showed anionic and polymeric nature and did not present toxicity against cabbage (Brassica oleracea var. capitata) seeds. The stability in the range of pH 4-10, salinity 5-25% and temperature 5-100°C, evidenced a highly stable biosurfactant, with promising potential of application in several industrial activities or environmental processes in adverse conditions.

Caatinga of Pernambuco is an area with a potential richness of microorganisms that produce biosurfactants, which are considered good candidates to replace synthetic surfactants in industrial applications due to their functional stability and low toxicity. In this context, current study aimed to investigate the biosurfactant production by the bacterium Enterobacter cloacae UCP 1597, isolated from the Caatinga soil. First fermentation was carried out in Erlenmeyer flasks containing 100 ml of medium, according to a 2³ full-factorial design (FFD). The results showed higher reduction in surface tension (28.3 mN/m) in condition 2 of the FFD, where dispersion of 38.46 cm2 of burnt motor oil was also verified. Then, a second fermentation was performed in Fernbach flasks, containing 2 L of selected medium, confirming reduction in surface and interfacial tension to 30.5 and 2.3 mN/m, respectively, as well as excellent emulsifying properties. The critical micellar dilution (CMD) of the crude biosurfactant was determined (70%) and its use in phytotoxicity assay verified the absence of toxicity for cabbage seeds. The biomolecule showed a high yield (13.69 g/L) after extraction with ethyl acetate and anionic and lipopeptide nature. The stability in acid pH, high temperature and salinity, showed an acid-resistant, thermostable, and halotolerant biocompound. Thus, this lipopeptide was shown to be a multifunctional biosurfactant, since it not only has excellent surface-active properties, but it is also a good emulsifier, dispersant, and potent agent to germination of cabbage seeds. Hence, is suggested its promising application in industrial activities or environmental processes under adverse conditions.

RESUMO -O presente trabalho investigou a desidratação da microalga Spirulina platensis em secador rotatório com recheio de inertes e os efeitos das variáveis operacionais nos teores de compostos bioativos da microalga desidratada. Observouse que, em condições específicas dessas variáveis, é possível obter teores satisfatórios de bioativos, reforçando o potencial da técnica estudada no aproveitamento dessa microalga.

A utilização de enzimas microbianas tem movimentado o mercado mundial industrial e/ou ambiental, pelo interesse nos processos que envolvem baixo custo energético e pela eficácia das enzimas. As proteases constituem um grande grupo de enzimas hidrolíticas que catalisam a hidrólise de proteínas e possuem diversas aplicações industriais. O gênero Aspergillus se apresenta como um excelente produtor de biomoléculas. A utilização de resíduos provenientes das indústrias de alimentos tem surgido como uma excelente alternativa para formulação de meios de produção em processos fermentativos, por apresentarem elevados índices de nutrientes em sua composição. Foram realizados ensaios de produção de protease através de planejamento fatorial 22 utilizando soro de leite e resíduo de sorvete. Os ensaios ocorreram durante 144 horas, 37Cº, 150 rpm. Os resultados obtidos indicaram que ambos os meios contendo os resíduos da indústria de alimentos obtiveram atividade proteolítica de 0,118U/mL para o soro de leite e de 0,093U/mL para o resíduo de sorvete, respectivamente. A utilização de resíduos na formulação de meios alternativos tem surgido como uma opção viável na produção de moléculas bioativas, pois reduzem os custos de produção enzimática.