Utilization of fish meal and fish oil for production of Cryptococcus sp. MTCC 5455 lipase and hydrolysis of polyurethane thereof

Abstract

Fish meal has been used as an additional nitrogen source and fish oil as inducer for the growth and production of lipase from Cryptococcus sp. MTCC 5455. A response surface design illustrated that the optimum factors influencing lipase production were fish meal, 1.5 %, w/v, Na2HPO4, 0.2 %, w/v, yeast extract, 0.25 %, w/v and sardine oil, 2.0 %, w/v with an activity of 71.23 U/mL at 96 h and 25 °C, which was 48.39 % higher than the conventional one-factor-at-a-time method. The crude concentrated enzyme hydrolyzed polyurethane (PUR) efficiently and hydrolysis was 94 % at 30 °C and 96 h. The products, diethylene glycol and adipic acid were quantified by HPLC and scanning electron microscopic studies of the degraded polymer showed significant increase in size of the holes from 24 to 72 h of incubation. Hydrolysis of PUR within 96 h makes the lipase novel for disposal of PUR and provides an innovative solution to the problems created by plastic wastes.

New insights into the microbial degradation of polyurethanes

“…Moreover the effect of so segment to hard segment ratio on the degradation rate of PEU matrix has also been assessed. 109 Although traditional biochemical enzymatic degradation of polyurethane appeared relatively inefficient, the development of new, specic arsenal in a selected organism will offer alternative methods for the production of side compounds with commercial value while degrading the pollutant. The lignin-based polyols used here were obtained by oxypropylation of four distinct lignins (Alcell, Indulin AT, Curan 27-11P, and Sarkanda).…”

The applicability of Impranil®DLN for gauging the biodegradation of polyurethanes

“…The protected composition of Impranil does complicate its use, so alternative non-colloidal polymers like poly(diethylene glycol adipate) [15,16], polycaprolactone [17], ethylphenylcarbamate [18], and diphenylmethane-4-4 0 -dibutylurea [19] dimers have been used for the purpose of mechanistic biodegradation studies. Bulk polyurethane biodegradation research has been performed by following changes in tensile strength or weight loss from polymer coupons over periods of weeks to months [20,21] but detailed mechanistic work was equivocal with these types of assays.…”

Evaluation of biological degradation of polyurethanes

“…Only one study on yeast was found, describing the growth of Cryptococcus sp. MTCC 5455 on fish waste to produce a lipase with activity on PU (Thirunavukarasu et al, 2015 (Oprea, 2010;Oprea and Doroftei, 2011;Oprea et al, 2016). Only a few studies are based on this norm and mentioned these strains.…”

“…SEM allows for a qualitative evaluation of the degradation on the surface after biological treatment by observation of cracks or holes on the degraded polymers. Enzymatic degradation generally leads to cracks (Figure 14a) or holes (Figure 14b) homogeneously spread at the TPU surface (Ozsagiroglu et al, 2012;Schmidt, J. et al, 2017) while degradation with a microbial consortium leads to irregularities (Figure 14c) (Das et al, 2017;Thirunavukarasu et al, 2015;Zafar et al, 2013). For instance, Das et al, showed the appearance of cracks at the surface of a polyester TPU degraded under composting conditions.…”