Effects of Aspergillus niger inoculum concentration upon the kinetics of starchy wastewater pretreatment in a tanks-in-series bioreactor under transitory conditions

Abstract

-This paper discusses the effects of three Aspergillus niger inoculum concentrations (0.12, 2.3 and 3.6 g/l) upon the kinetics of starch pretreatment under aerobic and transitory conditions using a tanks-in-series reactor. A synthetic wastewater containing starch as model polysaccharide was fed into the reactor system to study this polymer transformation by Aspergillus niger. Starch and metabolites (oligosaccharides with a molecular weight lower than 1 kDa) in the individual reactors were quantified respectively by the starch iodine complex (SIC) and anthrone methods. Enzyme activities were characterised with API ZYM kits. Starch degradation and metabolite accumulation were both influenced by both fungal inoculum and reactor HRT. Starch degradation improved from 34 to 99% with a parallel in increase inoculum concentration from 0.12 to 3.6 g/l. An overall of 400 mg/l of metabolites accumulated in the reactor system. A. niger secreted both extracellular and cell-wall-bound enzymes among which amylases.

Influence of silver nanoparticles on metabolism and toxicity of moulds

“…For A. niger, all 8 enzymes had low activity (5 nmol). The activity of 7 out of 8 enzymes (alkaline and acid phosphatase, esterase (C4), β-galactosidase, α-and β-glucosidase, naphtol-AS-BI-phosphohydrolase) was in agreement with the previous studies for A. niger (Coulibaly & Agathos, 2007;Janda et al, 2009). For P. chrysogenum 8 out of 10 enzymatic activities (alkaline and acid phosphatase, esterase (C4), esterase lipase (C8), naphtol-AS-BI-phosphohydrolase, β-glucosidase, N-acetyl-β-glucosamidase, leucin arylamidase) were confirmed (Gutarowska et al, 2010;Kołodziejczyk et al, 2014).…”