## 3 Results and Discussion
**Optimization of nutritional parameters for the biodegradation:** The presence of nutrients (carbon and nitrogen sources) in addition to media may support fungal growth in the presence dyestuff and will lead to an enhanced biodegradation process. Five carbon and nitrogen sources selected on the basis of previous studies (Table 2) were added simultaneously as a mixture and their effect on the biodegradation was monitored. The physical parameters were used as mentioned above for each of the effluents. The results confirmed that there is a significant increase in the biodegradation of all three textile industrial effluents after the addition of additional C and N sources [13,15]. There was almost a 10.00% increase (76.23 \(\pm\) 1.43% to 86.17 \(\pm\) 1.02%) in the biodegradation MT industrial effluent after the addition of carbon and nitrogen sources in the biodegradation mixture (Figure 4). The 3D response surface graphs indicated the positive response between different nutrients which lead to enhanced biodegradation of the effluents. The increase in the biodegradation was almost 7.00% (72.09 \(\pm\) 1.22% to 79.14 \(\pm\) 1.12%) in the FST industrial effluent (Figure 5). There was a 9.00% increase (67.16 \(\pm\) 1.24% to 76.22 \(\pm\) 1.16%) observed in the biodegradation of the ST industrial effluent after the addition of carbon and nitrogen sources in different ratios (Figure 6). Further analysis of the 3D response surface graphs showed that biodegradation increased when there was a low and equal amount (1:1) of all carbon and nitrogen sources present in the biodegradation mixture [15,22]. Presence of carbon sources up to 2.20% and nitrogen sources up to 1.20% (except ammonia) showed a positive effect on the biodegradation process. There was a decrease in the biodegradation% when ammonia was more than 1.25% in the biodegradation  
Figure 3: The 3D response surface graphs of interaction between parameters during the biodegradation of ST industrial effluent by _P. betulinus_ IEBL-3; there is positive interaction between (**a**)—pH and size of inoculum (**b**)—pH and temp. (**c**)—size of inoculum and time (**d**)—size of inoculum and temp. (**e**)—temp. and dye conc. (**f**)—statistical analysis. mixture. A higher concentration of ammonia than certain limits causes stress, which leads to lower microbial growth [23]. This may be due to the inhibitory effect of ammonia on proteins involved in microbial growth by degrading nutrients. Similarly, there is a lower biodegradation% in the current study at a higher ammonia concentration, possibly due to the inhibitory effect on enzymes involved in the process [4]. Further, additional nutrients in the media increased the biodegradation process only when present in the right amount and ratio; otherwise, it leads to the instability of the enzymes and lowers the biodegradation. There are other studies that have reported the positive roles of various carbon and nitrogen sources in the biodegradation of different dyes [13; 24]. Figure 4: Response surface 3D graphs showing effect of carbon and nitrogen sources on the biodegradation of Mujahid Textile (MT) industrial effluent by _P. betulinus_ IEBL-3; graphs represent positive interaction between (**a**) fructose and glucose, (**b**) ammonium nitrate and fructose and (**c**) ammonia and ammonium sulfate. (**d**) Statistical analysis indicating the significant effect of parameters (* indicate significance of value). Figure 5: Response surface 3D graphs showing effect of carbon and nitrogen sources on the biodegradation of Sitara Textile (MT) industrial effluent by _P. betulinus_ IEBL-3; graphs represent positive interaction between (**a**) ammonium nitrate and glucose, (**b**) ammonium sulfate and fructose and (**c**) ammonia and ammonium nitrate. (**d**) Statistical analysis indicating the significant effect of parameters (* indicate significance of value).