Enhanced submerged Aspergillus ficuum phytase production by implementation of fed-batch fermentation

Phytase is an important feed and food additive, which is both used in animal and human diets. Phytase has been used to increase the absorption of several divalent ions, amino acids, and proteins in the bodies and to decrease the excessive phosphorus release in the manure to prevent negative effects on the environment. To date, microbial phytase has been mostly produced in solid-state fermentations with insignificant production volumes. There are only a few studies in the literature that phytase productions were performed in submerged bench-top reactor scale. In our previous studies, growth parameters (temperature, pH, and aeration) and important fermentation medium ingredients (glucose, Na-phytate, and CaSO4) were optimized. This study was undertaken for further enhancement of phytase production with Aspergillus ficuum in bench-top bioreactors by conducting fed-batch fermentations. The results showed that addition of 60 g of glucose and 10 g of Na-phytate at 96 h of fermentation increased phytase activity to 3.84 and 4.82 U/ml, respectively. Therefore, the maximum phytase activity was further enhanced with addition of glucose and Na-phytate by 11 and 40 %, respectively, as compared to batch phytase fermentations. It was also reported that phytase activity increased higher in early log stage additions than late log stage additions because of higher microbial activity. In addition, the phytase activity in fed-batch fermentation did not drop significantly as compared to the batch fermentation. Overall, this study shows that fungal phytase can be successfully produced in submerged fed-batch fermentations

Food Biosynthesis

Alpha-keto acids are the deaminated form of amino acids, which have been used in several applications in the medicine, food, and feed industries. In vivo, alpha-keto acids are ketogenic or glucogenic precursors, which regulate protein turnover. Since alpha-keto acids do not have amino groups, substitution of amino acids with their specific alpha-keto acids in the diets helps kidneys and livers to reduce urea accumulation in the body. Additionally, alpha-keto acids are used in animal diets, especially in the poultry industry as a nutrient supplement for environmental and animal growth issues. Moreover, several alpha-keto acids have been reported to be used as flavor enhancers in the food industry. In this review, characteristics, chemical and biological production methods, detection analyses, and the application of various alpha-keto acids are summarized. Furthermore, potential future studies and applications of alpha-keto acids are discussed.</p

Screening of phytase producers and optimization of culture conditions for submerged fermentation

Phytase (myo-inositol-hexakisphosphate phosphohydrolase) is an enzyme, which breaks down phytate to inositol and orthophosphoric acid. Phytase has been used as feed additive, and in some medical applications for years. To date, phytase production has been usually performed as a solid-state fermentation with small production volumes. Therefore, the aim of this study was to increase the phytase activity in submerged fermentations by screening several microorganism strains based on the literature to select the most productive phytase producer and optimizing growth parameters such as temperature, pH, and aeration level using response surface methodology (RSM). As a result, among the four different microorganisms evaluated, Aspergillus ficuum (NRRL 3135) was selected as the most productive strain. Optimum temperature, pH, and aeration values were determined as 33 degrees C, 4.5, and 0.9 vvm, respectively, for A. ficuum in 2-l batch submerged phytase productions. Under these conditions, phytase activity was measured as 2.27 U/ml. Therefore, this is a unique study showing the production of phytase with A. ficuum successfully in submerged fermentation as opposed to the traditional solid-state fermentation

Enhancement and modeling of microparticle-added Rhizopus oryzae lactic acid production

Lactic acid has a wide industrial application area and can be produced by fungal strains. However, excessive bulk growth form of fungi during the fermentations is a major problem, which limits the fermentation performance. Microparticles are excellent tools to prevent bulk fungal growth and provide homogenized fermentation broth to increase uniformity and the prediction performance of the models. Therefore, in this study, addition of aluminum oxide and talcum microparticles into fermentations was evaluated to enhance the production of lactic acid by Rhizopus oryzae. The results showed that the bulk fungal growth was prevented and the lactic acid concentration increased from 6.02 to 13.88 and 24.01 g/L, when 15 g/L of aluminum oxide or 10 g/L of talcum was used, respectively, in the shake-flask fermentations. Additionally, substrate concentration, pH, and agitation were optimized in the bioreactors using response surface methodology, and optimum values were determined as 126 g/L of glucose, 6.22 pH, and 387 rpm, respectively. Under these conditions, lactic acid production further increased to 75.1 +/- A 1.5 g/L with 10 g/L of talcum addition. Also, lactic acid production and glucose consumption in the batch fermentation were successfully modeled with modified Gompertz model and modified logistic model. RMSE and MAE values for lactic acid production were calculated as 2.279 and 1.498 for the modified Gompertz model; 3.6 and 4.056 for the modified logistic model. Additionally, modified logistic model predicted glucose consumption with -2.088 MAE and 2.868 RMSE, whereas these values were calculated as 2.035 and 3.946 for the modified Gompertz model

Gıda Bileşenleri ve Katkı Maddelerinin Mikrobiyal Üretimi

Phytate, the major phosphorus source in plants, is reported to be a strong chelating agent, which can bind various nutrients in the body and cause malnutrition in animals and humans. In addition, phytate cannot be effectively utilized by monogastritic animals, which results in high amounts of phosphorus excretion in manure and adverse effects on the environment. Phytase can break down phytate and is secreted by various microorganism genera, such as&nbsp;Lactobacillus, Escherichia, Pseudomonas, Klebsiella,&nbsp;Mucor, Penicillium, Aspergillus,&nbsp;and&nbsp;Rhizopus&nbsp;spp. The addition of phytase to food and feed is important to prevent the negative effects of phytate. This chapter provides an extensive review about microbial phytase production, phytase characterization, various systems of phytase fermentation, and its application in the food and feed industries.</p