Molecular characterisation and biomass and metabolite production of Lactobacillus reuteri LPB P01-001: a potential probiotic

Lactobacillus reuteri LPB P01-001 was isolated from the gastrointestinal tract of wild swine and was characterised by biochemical testing and sequencing of gene 16S rRNA. A simple and low-cost culture medium based on cane sugar (2.5% p/v) and yeast extract (1% p/v) was used in the production of this probiotic. The fermentative conditions were a) pH control at 6.5 and b) no pH control; both were set at 37°C in a 12 L slightly stirred tank bioreactor. Fermentation parameters such as the specific growth rate, productivity and yield of biomass, lactic and acetic acid levels were determined. L. reuteri LPB P01-001 behaves as an aciduric bacteria because it grows better in a low pH medium without pH control. However, the lactic acid production yield was practically half (9.22 g.L-1) of that obtained under a constant pH of 6.5, which reached 30.5 g.L-1 after 28 hours of fermentation. The acetic acid production was also higher under pH-controlled fermentation, reaching 10.09 g.L-1 after 28 hours of fermentation. These parameters may raise the interest of those committed to the efficient production of a probiotic agent for swine.

Recovery of phytase produced by solid-state fermentation on citrus peel

The extraction of phytase produced by solid-state fermentation of citrus peel was studied employing a multistage leaching process. It was observed that the extracts containing EDTA retained over 90 percent of phytase activity at room temperature after 24 h after the leaching. A fractional design 2² (with 4 replicates at the central point) was carried out for testing the pH and agitation as process independent factors. Only the interaction between the pH and agitation showed a significant influence. These factors were optimized with a central composite design. Agitation at 300 rpm and pH at 5.0 were the best conditions to extract the enzyme from solid matrix. The modeling of the process indicated that diffusivity of the enzyme in the solvent was the controlling mechanism. The corresponding kinetic constant and saturation concentration in this process were 0.89 min-1 and 4.0 IU/mL, respectively. The multistage process indicated that after two steps, it was possible to recover 85 percent of total enzyme produced.

A extração de fitases produzidas por fermentação em estado sólido de polpa cítrica foi estudada utilizando um processo de extração sólido-líquido em varias etapas. A adição de EDTA permite manter durante 24 horas a temperatura ambiente 90 por cento da atividade inicial do caldo com a enzima extraída. Um planejamento fatorial 2², com 4 replicas no ponto central, foi desenvolvido para testar os valores de ph e agitação convenientes para a extração das enzimas. A interação entre ambos os fatores foi estadisticamente significativa. A atividade da enzima foi otimizada nos valores onde o pH (5.0) e a agitação (350 rpm) resultaram ser as melhores condições para extrair a enzima da matriz sólida. O ajuste do modelo matemático obtido mostra que é possível considerar a difusividade como o mecanismo que controla o processo de transferência de massa. A constante cinética que descreve este processo e a concentração de saturação foram 0.039 min-1 e 4.01 IU/mL respectivamente. A extração em varias etapas mostrou que nas duas primeiras etapas é possível recuperar 85 por cento da fitase produzida.

Xylanase production by Streptomyces viridosporus T7A in submerged and solid-state fermentation using agro-industrial residues

The study of xylanase production was conducted by Streptomyces viridosporus T7A in submerged (SmF) and solid-state fermentation (SSF), using agro-industrial residues and sub-products. Napier grass, sugarcane bagasse and soybean bran were used as carbon source, substrate/support, and nitrogen source, respectively. In SmF, Napier grass (1 percent v/w) supplemented with soybean bran, hydroxyethylcellulose and B complex vitamins were used. Soybean bran (1.5 percent w/v), B complex vitamins (0.1 percent), and hydroxyethilcellulose (0.15 percent) led to an increase in xylanase production (23.41 U/mL). In SSF, the effects of the following parameters were studied: substrate composition (sugarcane bagasse, Napier grass and soybean bran), initial moisture, and inoculum rate. In SSF, the highest xylanase activity (423.9 U/g) was reached with: 70 percent sugarcane bagasse, 20 percent Napier grass and 10 percent soybean meal, 90 percent of moisture, and 10(7)/g substrate.

A produção de xilanase por Streptomyces viridosporus T7A foi realizada em fermentação submersa (FSm) e fermentação no estado sólido (FES) utilizando resíduos e sub-produtos agroindustriais. Capim Napier, bagaço de cana e farelo de soja foram empregados como fonte de carbono, suporte/substrato e fonte nitrogênio, respectivamente. Em FSm, o capim Napier (1 por cento p/v) foi suplementado com farelo de soja (1,5 por cento p/v), hidroxietilcelulose (0,15 por cento) e vitaminas do complexo B (1,5 por cento) sendo que a produção de xilanase atingiu 23.41 U/mL. Em FES, o efeito dos seguintes parâmetros foi estudado: composição do substrato (bagaço de cana, Capim Napier e farelo de soja), umidade inicial, aeração e taxa de inoculação. A mais elevada produção de xilanase (423,9 U/g) foi atingida com 70 por cento bagaço de cana, 20 por cento de capim Napier e 10 por cento farelo de soja, 90 por cento de umidade inicial e 10(7) células/g substrato.