Production of phytase from Pichia fermentans and its application as a plant growth-promoting agent
摘要
The phylogenetic affiliation of yeast microorganisms newly isolated from 4 different brands of Bulgarian cereal beverage Boza was studied to identify phytase-producing strains. Eight pure cultures were isolated and characterised based on morphological and genetic features. Five of them belonged to the Pichia fermentans species. Representatives of the genera Candida and Rhodotorula were also identified. Phytase activity was detected for two Pichia fermentans strains designated B4-1 and B4-2. The isolate B4-1 was chosen for further investigation of the phytase production based on its higher extracellular phytase activity (0.5 U mL−1) in a synthetic PSM medium with sodium phytate as the only source of phosphorus. Optimal phytase production was observed at T 30 °C and an initial pH of 5.0–5.5. The extracellular enzyme activity increased 1.5-fold after optimisation of culture media composition. The strain produced extracellular phytase during exponential and stationary growth phases, with the maximum phytase synthesis observed between 48 and 72 h of cultivation. At the laboratory scale, the phytase enzyme effectively enhanced growth and increased plastid pigment concentrations in Cucurbita pepo L., highlighting its potential role as a plant growth-promoting microorganism (PGPM).