Dhale Mohan A, Mohan-Kumari H Puttananjaiah
Department of Food Microbiology, Central Food Technological Research Institute, Council of Scientific and Industrial Research, Mysore, 570 020, India.
Department of Grain Science & Technology, Central Food Technological Research Institute, Council of Scientific and Industrial Research, Mysore, 570 020, India.
J Microbiol Methods. 2014 Jul;102:66-8. doi: 10.1016/j.mimet.2014.04.010. Epub 2014 Apr 30.
Fungi are well known to produce various industrial enzymes and secondary metabolites with different colours. Fungi producing l-asparaginase enzyme are conventionally screened on medium containing phenol red (PR). The contrast between enzyme-hydrolysed zone and unhydrolysed l-asparagine is not very evident and distinct in medium containing PR and bromothymol blue (BB) due to coloured secondary metabolite production. Thus, PR and BB limit and affect the detection and screening method. In the present investigation, an improved method for screening is reported by comparing with PR and BB, wherein methyl red (MR) is incorporated as pH indicator. The enzyme activity was distinctly observed (red and light-yellow) in MR incorporated medium compared to PR and BB.
众所周知，真菌能产生各种具有不同颜色的工业酶和次生代谢产物。传统上，生产L-天冬酰胺酶的真菌是在含有酚红（PR）的培养基上进行筛选的。由于有色次生代谢产物的产生，在含有PR和溴百里酚蓝（BB）的培养基中，酶水解区和未水解的L-天冬酰胺之间的对比度不是很明显。因此，PR和BB限制并影响了检测和筛选方法。在本研究中，通过与PR和BB进行比较，报道了一种改进的筛选方法，其中加入甲基红（MR）作为pH指示剂。与PR和BB相比，在加入MR的培养基中能明显观察到酶活性（红色和浅黄色）。
