Incubation temperature is one of the most important factors in SSF because growth and enzyme production depends on temperature. Arora and Gill 2001; Pointing et al 2000) reported that fungi are generally cultivated between the temperature ranges of 25 to 30°C. In our present study lignocellulolytic enzyme production from G.gibbosum and L. sajor – caju were tested in the temperature range of 15 to 35°C. The maximum enzyme production was obtained at 25°C. The optimum temperature for laccase also was found to be 25°C. Further increase in temperature did not increase the production this may be due to the denaturation of metabolites, enzyme alteration in cell membrane , reduced microbial activity fact that at higher temperature (thesis 4). However at lower temperature also reduced productivity was reported that may be due to slowing down of metabolic activities of the fungus. Xin and Geng 2011 have also reported reduction in enzyme production at lower temperature from Trametes versicolor due to retardation of metabolic rate. Ravikumar et al. 2012; Chhaya and Gupte 2013; Elsayed et al. 2012) and many other researchers also reported that temperature between 25 to 30°C to be optimum for laccase enzyme production from white rot fungi. Similarly Iqbal et al 2011 reported 30°C to be optimum temperature and 28 to 30°C reported by Elshafei et al 2012 to be optimum for laccase enzyme production from Penicillium maetensii NRC 345. Zadrazil et al. 1996; Arora and Gill 2000; Tripathi et al. 2008, found that temperature ranging from 25 to 37°C to be optimum for ligninases production from white rot fungi. Tekere et al 2001 found that the optimum temperature for cultures of Coriolus (Trametes, Polyporus) versicolor and P. chrysosporium for ligninase synthesis in SSF varied between 25 – 37°C. Arora and Gill 2000; Tripathi et al., 2008 also reported a significant influence of incubation temperature on lignolytic enzyme production from Pleurotus sp, Dichomitus and other white rots. Latifian et al., 2007 also reported optimum temperature for cellulase production from Trichoderma reesei under SSF was in range of 25 – 30°C, which is comparable with our results. Siddheshwar et al., 2017 reported 30°C for xylanase production from Nocardiopsis sp.KNU under SSF.
Effect of moisture level
During enzyme production under SSF the end product and water requirement of fungus depends entirely on substrate to moisture ratio and also on water holding capacity of substrate used (Kim et al.1985; Asgher et al.2006). Increasing the moisture level from 1:2 to 1:6 causes an enhancement of the fungal growth and enzyme production. Wheat bran and saw dust was fermented at 1:4 (w/v) moisture gave maximum lignocellulolytic production by both strains. However an increase in moisture level of more than 1:4 caused a significant decrease in enzyme activities (Fig). In present study 1:4 substrate to moisture ratio was found to be optimum for lignocellulolytic enzyme production. Higher and lower moisture levels were inhibitory, leading to secretion of lower activities of ligninases in secondary growth due to poor accessibility of nutrients and limited aeration (Regina et al., 2008; Shaheen et al., 2008; Bhatti and Nawaz, 2009). Comparable to our result Patel et al., 2016 also reported 1:4 (w/v) substrates to moisture ratio to be optimum for laccase production from Tricholoma giganteum under SSF. Hemansi et al., 2018 reported 1:3.5 substrate to moisture ratio for cellulase production from Aspergillus niger.
Effect of nitrogen source
The nitrogen source is important for industrial fermentation medium designing to meet maximum enzyme production. The effect of nitrogen sources on enzyme production of both strains by incorporating various nitrogen sources at 0.05% into the production medium under SSF. The maximum ligninases and cellulases were recorded on addition of ammonium sulphate whereas ammonium dihydrogen phosphate was found to be best nitrogen source in enhancing xylanase production probably because this complex nitrogen contains more element that are necessary for the metabolism of fungi (Bairagi et al., 2016).