RESUMEN
Objective: To lay a foundation for elucidating the mechanism of microbial regulation of γ-amino butyric acid (GABA) formation in the processing of Sojae Semen Praeparatum. Methods: The ability of glutamic acid decarboxylase and protease (neutral protease, alkaline protease and acid protease) production of Bacillus subtilis, Enterococcus avium, Enterococcus faecium, Bacillus amyloliquefaciens, Aspergillus niger, Aspergillus flavus, Aspergillus tamarii, Penicillium citrinum, Cladosporium tenuissimum, Phanerochaete sordida, Rhizopus oryzae, Sporidiobolus salmonicolor in different pH and temperature conditions were determined by Berthelot colorimetry and Folin phenol method. Results: The GAD and protease activities of the twelve strains were stronger at pH 5-7 and temperature 28-37 ℃. The highest GAD enzyme activity from A. flavus was 41.97 U/h, the optimum pH was 7 and the temperature was 28 ℃, followed by S. salmonicolor, A. niger, R. oryzae, and B. subtilis, respectively. The enzyme activities were 29.04, 25.78, 22.42 and 19.43 U/h. The highest neutral protease activity of B. subtilis was 24.80 U/mL, the optimum pH was 7 and the temperature was 37 ℃, followed by B. amyloliquefaciens, R. oryzae and E. avium. The enzyme activities were 16.86, 12.51 and 9.18 U/mL. The highest alkaline protease activity of B. amyloliquefaciens was 13.29 U/mL, the optimum pH was 7 and the temperature was 34 ℃, followed by B. subtilis and R. oryzae. The enzyme activities were 8.86 and 6.20 U/mL, respectively. The ability of 12 kinds of microorganisms to produce acid protease was generally poor. Conclusion: The optimal pH and temperature of the 12 kinds of microorganisms selected for this experiment are basically consistent with the natural processing of Sojae Semen Praeparatum. Among them, fungi have stronger GAD production capacity and bacteria have stronger neutral protease production capacity. The high GABA concentration of Sojae Semen Praeparatum is caused by the joint action of multiple strains.
RESUMEN
Aim: The present study was carried out to enhance the production of α-amylase by pelleted Aspergillus tamarii through optimization of various media compositions and cultivation conditions using shake flask and bioreactor experiments. Methodology: Shake flask experiments were conducted to study the effect of pH, temperature and starch concentration using Response Surface Methodology (RSM) and other parameters, namely, nitrogen source, inoculum size and incubation days using single variable optimization technique for the pelleted growth of microorganism and amylase production. Scale up study was carried out for the assessment of results obtained from shake flask experiments using a laboratory scale bioreactor. In the bioreactor study, parameters, namely, pH control, agitation and aeration were considered. Results: Maximum amylase production using pelleted Aspergillus tamarii was achieved at initial pH 6.7, temperature 30.5 °C, 0.5% w/v starch, 0.1% w/v urea, 1.5% v/v inoculum size and 4 days of fermentation in the shake flask experiments. Filamentous growth was observed when the concentration of starch used was above 2%. The specific enzyme activity increased to 2.77 fold after partial purification. When enzyme was used for desizing cotton fabric, it produced 90% efficiency. The scale-up experiments revealed initial pH 6.7, agitation 300 rpm and aeration 1 vvm as the conditions suitable for pelleted growth, as well as to achieve maximum amylase production. Interpretation: The results indicate pelleted growth of Aspergillus tamarii and in turn achievement of maximum amylase activity depends on media composition and fermentation conditions used at the time of enzyme production. Efficient desizing of cotton fabric by amylase showed its effectiveness towards hydrolysis of starch and converting it to soluble products for easy removal.
RESUMEN
The production of tannase by Aspergillus tamarii was studied in submerged cultures. The fungus produced an extracellular tannase after two days of growth in mineral medium containing tannic acid, gallic acid and methyl gallate as carbon source. The best result was obtained using gallic acid as inducer (20.6 U/ml). The production of enzyme was strongly repressed by the presence of glucose. Crude enzyme was optimally active at pH 5.0 and 30º C. The enzyme was stable in a large range of pH and up to the temperature of 45º C.
A produção de tanase por um novo potencial produtor, o fungo filamentoso Aspergillus tamarii, foi parcialmente caracterizada neste estudo. O fungo produziu uma tanase extracelular em culturas submersas após 2 dias de crescimento em meio mineral contendo ácido tânico, ácido gálico ou metil galato como fonts de carbono. Os melhores resultados foram obtidos em culturas com ácido gálico (20,6 U/ml). A produção da enzima foi fortemente inibida por glicose. A enzima bruta foi otimamente ativa em pH 5,0 e a 30º C e estável em ampla faixa de pH e em temperaturas inferiores a 45ºC.