Chiang Mai Journal of Science

This research demonstrated a new method to utilize nutrient composition in non-rubber skim latex for Poly (L-lactic acid) (PLA)-degrading enzymes production due to the enzyme is a very important trend regarding recycling plastic wastes in the future. Moreover, we attempted to find an alternative supporter such as scrub pad for cell immobilization and used as material for the enzyme production under open continuous fermentation. The PLA-degrading enzyme production was determined using a non-rubber skim latex and basal medium containing 0.035% (w/v) PLA powder and 1% (w/v) scrub pad as a supporter for the bacterial cells in a shake flask and fermenter. The effect of the physical parameters and the nitrogen sources were studied. The following optimal conditions were used: gelatin as the nitrogen source, a temperature of 45°C, an initial pH of 7.0, an agitation speed of 100 rpm, without aeration support and 3 days of cultivation. This resulted in an activity of approximately 41 U/ml and 0.56 U/ml.h of productivity in the 2 L fermenter. The highest PLA-degrading activity, 45 U/ml, was achieved in the fermenter by a continuous process under open fermentation with a dilution rate of 0.013 h-1. These results mean that non-rubber skim latex has the potential for PLA-degrading enzyme production through an open fermentation method in strain T16-1.