Simultaneous production of ligninolytic enzymes by a temperature and pH tolerant strain of Aspergillus niger under different cultural conditions

Ligninolytic activity, represented by laccase, lignin peroxidase (LiP) and manganese peroxidase (MnP), of a temperature and pH tolerant strain of Aspergillus niger isolated from a temperate location in the Indian Himalayan Region (IHR), has been studied under different cultural (physico-chemical & nutritional) conditions. In plate assays, the fungus exhibited ligninolytic activity at wide range of temperature (5-45°C) and pH (3.5-9.5). In quantitative estimations, carried out at 15, 25 and 35°C, production of laccase was favoured by low temperature (15°), while production of LiP and MnP were favoured by higher temperatures (25 & 35°C). At optimum growth temperature (25°C), laccase production was the maximum at 7.5 pH. LiP and MnP production was favoured between 7.5 to 9.5, and 5.5 to 9.5 pH, respectively. Amongst nutritional sources, nitrogen sources were recorded as better enhancers for enzyme production, followed by vitamins and carbon sources. Folic acid (0.01%) was also found to be a good enhancer for production of all the three enzymes.