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

Abstract

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 °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.

PRODUCTION AND CHARACTERIZATION OF PHYTASE FROM INDIGENOUS Aspergillus niger ISOLATES

“…for phytase production through cobalt chlorie staining. Cobalt chloride staining is used to rule out false positive results (Coban and Demirci, 2014). Out of 20, only 9 (45%) A. niger isolates were screened as positive on PSM media.…”

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

“…4), which was very similar compared to the predicted value from the model, which clearly demonstrated the model represents the fermentation successfully. Additionally, maximum glucose consumption rate and maximum phytase activity production rate were calculated as 0.70 g glucose ml -1 h -1 and 0.0426 U ml -1 h -1 , respectively, under optimized conditions, which were both around 2-fold more compared to base medium production results (COBAN & DEMIRCI, 2014). …”

“…In our previous study, Aspergillus fi cuum phytase activity was obtained as 1.02 U ml -1 in shake-fl ask productions. After scaling up to 1-liter (working volume) bioreactors and optimizing of the growth parameters, phytase activity increased to 2.27 U ml -1 (COBAN & DEMIRCI, 2014). There are also several other studies performed in the literature to optimize fermentation medium composition for phytase production with different microorganisms.…”

“…Aspergillus fi cuum (NRRL 3135) was used in this study as suggested by our previous study (COBAN & DEMIRCI, 2014). A. fi cuum was obtained from Agricultural Research Service Culture Collection (Peoria, IL) and grown on potato dextrose agar (PDA) (Difco, Sparks, MD) slants for 6 days at 30 °C and stored at 4 °C as the working culture.…”

“…Reactors were inoculated with 3% (v/v) prepared inoculum. Fermentation runs were performed at 33 °C, 4.5 pH, and 0.9 vvm aeration as suggested by our previous studies (COBAN & DEMIRCI, 2014). Agitation was maintained at 300 r.p.m.…”