Exploring the potential of immobilized phytase to enhance phosphorus uptake by Catharanthus roseus

Abstract

The current study was designed to establish stable phytases, using poly-(acrylamide-co-acrylic acid) hydrogels as an entrapment matrix, for their application in the promotion of plant growth. Different production parameters were optimized to gain the maximum enzyme yield of 14.3 ± 0.41 U/g and a protein content of 0.7 ± 0.03 mg/ml from Rhizopus oligosporus under solid-state fermentation. For plants, phytase is a source of phosphorus, an essential nutrient for their growth. The study outlined the standardized conditions for the physical entrapment of phytase within polyhydrogel as; 1.5 ml APS, 0.25 ml enzyme, and a 12-minute procurement period. Moreover, the optimal temperature and pH for the partially purified immobilized enzyme were recorded as 50 ºC and 7.5, respectively, under the optimized conditions. The immobilized enzyme has shown enhanced stability over the free enzyme at 70 °C and a wide pH range. During the study, the maximum enzyme activity achieved by partially purified free and immobilized phytase was 7.65 ± 0.43 and 9.12 ± 0.28 U/g. Furthermore, the characterization of the poly-hydrogel revealed that it contains a rough and porous 3-D structure, with abundant cross-linking channels. In a pot experiment, phytase-entrapped poly-(acrylamide-co-acrylic acid) hydrogel was applied to the soil and displayed a positive impact upon different growth parameters as well as phosphorus content of the C. roseus than free enzyme and control groups. The phosphorus-status of the soil having entrapped phytase, increased up to 1.69 and 2.17-fold compared to the plants of free enzyme and control. The study has shown that immobilized phytase was effective to deliver phytate-P to Catharanthus roseus as it significantly increased its rate of photosynthesis (25.9 ± 1.4 µ mol m−2s−1), shoot length (36.1 ± 1.3 cm), and leaf chlorophyll content (56.7 ± 2.8) as compared to the other experimental groups. Overall, the work declares the considerable potential of phytases in phosphorus uptake and plant growth-promoting activities.