Invertase production by Aspergillus niger under solid state fermentation: Focus on physical–chemical parameters, synergistic and antagonistic effects using agro-industrial wastes

Abstract This study reports the application of experimental mixture design as a tool to evaluate the effects of different formulations of media cultivation in invertase production by Aspergillus niger LBA 02 under solid state fermentation (SSF) using wheat bran, soybean meal, cottonseed meal and orange peel as agro-industrial waste substrates. Invertase production was correlated with the physical–chemical parameters of the agro-industrial wastes; it was shown that protein and ash content as well as high apparent density positively influences invertase production. Synergistic effects between the agro-industrial wastes were observed during the fermentation process; however, in most cases, soybean meal presented the highest positive effects on invertase production. After 48 h of fermentation, the formulation containing wheat bran, cottonseed meal and orange peel in equal proportions presented an interesting synergistic effect, reaching predicted values of enzyme activity higher than 100 μg −1 . At 72 h of fermentation, the mixture of wheat bran, soybean meal and cottonseed meal in equal proportions reached predicted values higher than 140 μg −1 . A statistical tool demonstrated an efficient strategy for enhancing enzyme production and evaluating synergistic effects between agro-industrial wastes from various sources. Furthermore, this process can also be applied in studies regarding waste prices, availability and profitability because this work presented alternatives for the formulation of media cultivation containing different agro-industrial wastes and the effects on enzyme production.