Hasan B. Coban

Enhanced phenylpyruvic acid production with Proteus vulgaris in fed-batch and continuous fermentation.

ABSTRACT Phenylpyruvic acid is a deaminated form of phenylalanine and is used in various areas such as development of cheese and wine flavors, diagnosis of phenylketonuria, and to decrease excessive nitrogen accumulation in the manure of farm animals. However, reported phenylpyruvic acid fermentation studies in the literature have been usually performed at shake-flask scale with low production. In this study, phenylpyruvic acid production was evaluated in bench-top bioreactors by conducting fed-batch and continuous fermentation for the first time. As a result, maximum phenylpyruvic acid concentrations increased from 1350 mg/L (batch fermentation) to 2958 mg/L utilizing fed-batch fermentation. Furthermore, phenylpyruvic acid productivity was increased from 48 mg/L/hr (batch fermentation) to 104 and 259 mg/L/hr by conducting fed-batch and continuous fermentation, respectively. Overall, this study demonstrated that fed-batch and continuous fermentation significantly improved phenylpyruvic acid production in bench-scale bioreactor production.

Improved submerged Aspergillus ficuum phytase production in bench-top bioreactors by optimization of fermentation medium

Phytase is an important feed and food additive, which is used in diets to increase the absorption of 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, phytase has been mostly produced in solid state fermentations with insignificant production volumes. Thus, there is a need to produce phytase in submerged fermentations, which can be scaled-up for commercial productions. Additionally, optimization of fermentation medium has not been studied well in the literature. Therefore, this study has been undertaken to improve Aspergillus ficuum phytase production in submerged fermentations by optimizing important nutrients in the fermentation medium (glucose, Na-phytate, and CaSO4) using Box-Behnken design of Response Surface Methodology. Also, effects of pH and temperature on phytase activity were studied. Optimum glucose, Na-phytate, and CaSO4 concentrations were determined as 126, 14, and 1....

Enhanced phenylpyruvic acid production with Proteus vulgaris by optimizing of the fermentation medium

Alpha keto acids are important food additives, which commonly produced by microbial deamination of amino acids. In this study, production of phenylpyruvic acid (PPA), which is the alpha keto acid of phenylalanine was enhanced in 2-l bench scale bioreactors by optimizing of fermentation medium composition using the Box-Behnken Response Surface Methodology (RSM). Optimum glucose, yeast extract, and phenylalanine concentrations were determined to be 119.4 g 1−1, 3.7 g 1−1, and 14.8 g 1−1, respectively, for PPA production, and 163.8 g 1−1, 10.8 g 1−1, and 9.8 g 1−1, respectively, for biomass production. Under these optimum conditions, PPA concentration was enhanced to 1349 mg 1−1, which was 28% and 276% higher than the unoptimized bioreactor and shake-flask fermentations, respectively. Moreover, P. vulgaris biomass concentration was optimized at 4.36 g 1−1, which was 34% higher than under the unoptimized bioreactor condition. Overall, this study demonstrated that optimization of the fermentation media improve...

Chapter 2 – Phytase as a Diet Ingredient: From Microbial Production to Its Applications in Food and Feed Industry

Abstract 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 Lactobacillus, Escherichia, Pseudomonas, Klebsiella , Mucor, Penicillium, Aspergillus, and Rhizopus 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.

Applied Research Perspectives of Alpha-Keto Acids: From Production to Applications

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.

Screening of Phytase Producer Microorganisms and Optimization of Growth Conditions in Submerged Fermentation

Abstract. Phytase is an enzyme, which breaks down phytate to inositol and orthophosphoric acid. Phytate is the major phosphorus source in plants and plays an important role during germination for ATP synthesis. However, six reactive groups of phytate make it a polyanionic chelating agent, which reacts with proteins, amino acids, and divalent cations. Therefore, phytate consumption may cause bone weaknesses, tooth decays, iron deficiencies, and general malnutrition. In addition, while ruminant animals sustain the microflora, which breaks down phytate; monogastric animals such as chickens and pigs can produce little or no phytase in their intestine. Since, monogastric animals are generally fed with soybean and other meals, which have a high concentration of phytate, excessive phosphorus accumulation occurs in their manure. This causes problems such as water pollution, algal blooms, fish kills, and changing of fauna and flora in the environment. In order to solve these problems, supplementing diets with phytase as the feed additive is getting attention in the food and feed industry. 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 o C, pH 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, which is 2 folds higher than shake-flask fermentations. 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.