ABSTRACT
ABSTRACT: A synthetic medium containing glucose, glycerol, yeast extract (YE), and ammonium sulfate (AS) was compared to several low-cost media in their ability to produce high emulsification index (EI). The goal was to reduce the production costs of an emulsifier with application in food oil-in-water emulsions. To this end, agro-industrial by-products were screened for bioemulsifier production from Yarrowia lipolytica. The statistical analysis showed that the EIs of media containing residual frying oil from palm oil (RFO_palm) or soybean oil (RFO_soy), residual liquid from butter production (butter whey, BWhey) or cheese production (cheese whey, CWhey), supplemented with YE and AS were similar to the EI of the synthetic medium. The replacement of YE by corn steep liquor (CSL) also resulted in similar EI, except for RFO_soy. BWhey was tested with CSL without AS and similar EI (66.8%) was detected in comparison to that of the same medium with AS (66.3%). The cell-free broth obtained after Y. lipolytica growth in BWhey+CSL was successfully used to obtain vegetable oil-in-water emulsions indicating its potential application in food products.
RESUMO: O meio sintético contendo glicose, glicerol, extrato de levedura (YE) e sulfato de amônio (AS) foi comparado a meios de baixo custo para produzir alto índice de emulsificação (EI). Para este fim, os subprodutos agroindustriais foram rastreados quanto à produção de bioemulsificante por Yarrowia lipolytica. A análise estatística mostrou que EI de meios contendo óleo de fritura residual de óleo de palma (RFO_palm) ou óleo de soja (RFO_soy), líquido residual da produção de manteiga (soro de manteiga, BWhey) ou da produção de queijo (soro de queijo, CWhey), suplementado com YE e AS foram semelhantes ao EI do meio sintético. A substituição do YE por milhocina (CSL) também resultou em EI semelhante, exceto no RFO_soy. O BWhey foi testado com CSL sem AS e EI semelhante (66,8%) foi detectado em comparação com o mesmo meio com AS (66,3%). O meio isento de células obtido após o crescimento de Y. lipolytica no meio BWhey + CSL foi utilizado com sucesso para obter emulsões de óleo vegetal em água, indicando sua potencial aplicação em produtos alimentícios.
ABSTRACT
The plant growth-promoting rhizobacterial strain Pseudomonas putida Rs-198 was isolated from salinized soils from Xinjiang Province. We optimized the composition of the low-cost medium of P. putida Rs-198 based on its bacterial concentration, as well as its phosphate-dissolving and indole acetic acid (IAA)-producing capabilities using the response surface methodology (RSM), and a mathematical model was developed to show the effect of each medium component and its interactions on phosphate dissolution and IAA production. The model predicted a maximum phosphate concentration in medium containing 63.23 mg/L inorganic phosphate with 49.22 g/L corn flour, 14.63 g/L soybean meal, 2.03 g/L K2HPO4, 0.19 g/L MnSO4 and 5.00 g/L NaCl. The maximum IAA concentration (18.73 mg/L) was predicted in medium containing 52.41 g/L corn flour, 15.82 g/L soybean meal, 2.40 g/L K2HPO4, 0.17 g/L MnSO4 and 5.00 g/L NaCl. These predicted values were also verified through experiments, with a cell density of 10(13) cfu/mL, phosphate dissolution of 64.33 mg/L, and IAA concentration of 18.08 mg/L. The excellent correlation between predicted and measured values of each model justifies the validity of both the response models. The study aims to provide a basis for industrialized fermentation using P. putida Rs-198.