Valorization of chicken feathers for polyhydroxyalkanoates production using Rohodococcus quinshengii LS18 and the biodegradation studies with the extracted polymer and its blends.

Abstract

Polyhydroxyalkanoates (PHAs) are promising polymer in the battle against plastic pollution. Here, Rhodococcus qingshengii LS18 bacterial strain recovered from abattoir soil was identified as significant PHA producer (2.16 g/L PHA). Amongst five animal wastes tested, chicken feathers (2.2 g/L) were found to be best for PHA production from R. qingshengii LS18. Finest conditions for PHA production after statistical optimization were found at 120 h with 40 g/L chicken feathers and 1 g/L urea at 80 rpm which showed 2.6 times increment in PHA production as compared to One-factor-at-a-time optimization (OFAT). The extracted PHA was analysed using NMR, FTIR, XRD and GCMS. The melting temperature (T_m) of microbial PHA was recorded at 176.63 °C as per DSC analysis and this polymer suffered complete disintegration at ~ 300 °C as per the TGA profile which is better than the standard PHA (~ 283.14 ± 10 °C). Blending of microbial PHA was done to overcome the brittleness with sole extracted PHA and for better degradation capability. Best PHA blend obtained with gelatin and Egg shell powder (ESP) in ratio 2:1:1 where 94% Elongation at break, 62% Elongation at max load and 9.81 MPa Tensile strength was found. Here, biodegradation rate of PHA blend in unaltered garden soil (at 30-40 °C, humidity ~ 30%, pH 7.4) was recorded to be 94% on 60th day of soil burial experiment. The study concludes that R. qingshengii LS18 is a promising PHA producer having the ability to utilize chicken feathers in optimised conditions and can be used for packaging applications in the form of PHA blends.