Thanasak LomthongSrisuda HanphakphoomRangrong YoksanVichien Kitpreechavanich2025-03-102025-03-102015International Biodeterioration and Biodegradation964830510.1016/j.ibiod.2015.07.0112-s2.0-84938078876https://repository.dusit.ac.th//handle/123456789/4841The co-production of poly-(l-lactide)-degrading enzyme and raw starch-degrading enzyme by the thermophilic filamentous bacterium Laceyella sacchari LP175 in liquid medium using low-cost agricultural crops as substrates was investigated. Statistical mixture design experiments indicated that 5g of raw material - consisting of 2.35gL-1 cassava chips and 2.65gL-1 soybean meal in a suspension of 2.0gL-1 K2HPO4 and 1.0gL-1 KH2PO4 - gave the highest production of both enzymes when the culture was grown at 50�C for 24h cultivation. Addition of 1.0gL-1 of poly-(l-lactide) powder and 1.0gL-1 cassava starch to the medium increased poly-(l-lactide)-degrading enzyme and raw starch-degrading enzyme, respectively. Response surface methodology by central composite design found that the optimized concentration of 0.52gL-1 poly(l-lactide) powder and 3.34gL-1 cassava starch increased poly-(l-lactide)-degrading enzyme and raw starch-degrading enzyme activities up to 68.8UmL-1 and 86.1UmL-1, respectively. The 2% poly-(l-lactide)/thermoplastic starch (PLLA/TPS) blend (50:50) film was degraded up to 99.7% of weight loss by the crude enzyme at an initial pH of 9.0 for 4h. The high efficiency on biodegradation of poly-(l-lactide)/thermoplastic starch blend polymer by the obtained mixed enzymes from cheap and abundant agricultural products could be applied to reduce global environment from non-biodegradable materials. � 2015 Elsevier Ltd.BiodegradationLaceyella sacchari LP175Mixture designPoly(l-lactide)-degrading enzymeRaw starch-degrading enzymeArticleScopus