Department of Biotechnology, Manipal Institute of Technology, Manipal Academy of Higher Education, Manipal, Karnataka, 576104, India.
Curr Microbiol. 2020 Aug;77(8):1540-1549. doi: 10.1007/s00284-020-01957-w. Epub 2020 Apr 4.
Phytate-linked nutritional deficiency disorders have plagued poultry for centuries. The application of exogenous phytases in poultry feed has served as a solution to this problem. However, they are linked to certain limitations which include thermal instability during prolonged feed processing. Therefore, in this study, Streptococcus thermophilus 2412 based phytase stability was assessed at higher temperatures up to 90 °C. This was followed by probiotic validation of the same bacterium in an in vitro intestinal model. Bacterial phytase showed thermostability up to 70 °C with a recorded activity of 9.90 U. The bacterium was viable in the intestinal lumen as indicated by the cell count of 6.10 log(CFU/mL) after 16 h. It also showed acid tolerance with a stable cell count of 5.01 log(CFU/mL) after 16 h of incubation at pH 2. The bacterium displayed bile tolerance yielding a cell count of 6.36 log(CFU/mL) in the presence of 0.3% bile. Bacterial susceptibility was observed toward all tested antibiotics with a maximum zone of 20 mm against clindamycin. The maximum antagonistic activity was observed against Staphylococcus aureus, Serratia marcescens, and Escherichia coli with inhibition zone diameters up to 10 mm. The above characteristics prove that S. thermophilus 2412 can be used as an effective phytase-producing poultry probiotic.
植酸结合性营养缺乏症困扰家禽已有数百年之久。在禽饲料中应用外源植酸酶是解决这一问题的方法之一。然而，它们也存在一定的局限性，包括在长时间的饲料加工过程中热不稳定性。因此，在本研究中，我们评估了嗜热链球菌 2412 来源的植酸酶在高达 90°C 的高温下的稳定性。随后，我们在体外肠道模型中对同一种细菌进行了益生菌验证。细菌植酸酶在 70°C 下表现出热稳定性，活性记录为 9.90 U。细菌在肠道腔中具有生存能力，16 小时后细胞计数为 6.10 log(CFU/mL)。它还表现出耐酸性，在 pH 2 下孵育 16 小时后，稳定的细胞计数为 5.01 log(CFU/mL)。细菌在存在 0.3%胆汁的情况下表现出胆汁耐受性，细胞计数为 6.36 log(CFU/mL)。细菌对所有测试的抗生素均表现出敏感性，对克林霉素的最大抑菌环为 20mm。最大的拮抗活性观察到对金黄色葡萄球菌、粘质沙雷氏菌和大肠杆菌，抑制环直径高达 10mm。上述特性证明嗜热链球菌 2412 可用作有效的产植酸酶家禽益生菌。
