Co-production of poly(l-lactide)-degrading enzyme and raw starch-degrading enzyme by Laceyella sacchari LP175 using agricultural products as substrate, and their efficiency on biodegradation of poly(l-lactide)/thermoplastic starch blend film. (October 2015)

• Record Type: Journal Article
• Authors: Lomthong, Thanasak; Hanphakphoom, Srisuda; Yoksan, Rangrong; Kitpreechavanich, Vichien
• Is Part Of: International biodeterioration & biodegradation. Volume 104(2015)
• Page Start: 401
• Page End: 410
• Publication Date: 2015-10
• Subjects: Poly(l-lactide)-degrading enzyme -- Raw starch-degrading enzyme -- Laceyella sacchari LP175 -- Mixture design -- Biodegradation; Biodegradation -- Periodicals; Bioremediation -- Periodicals; Biodegradation -- Periodicals; Biodégradation -- Périodiques; Biorestauration -- Périodiques; Electronic journals; 620.11223
• DOI: 10.1016/j.ibiod.2015.07.011
• Languages: English
• ISSNs: 0964-8305

Abstract

Abstract: The 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 5 g of raw material – consisting of 2.35 g L −1 cassava chips and 2.65 g L −1 soybean meal in a suspension of 2.0 g L −1 K2 HPO4 and 1.0 g L −1 KH2 PO4 – gave the highest production of both enzymes when the culture was grown at 50 °C for 24 h cultivation. Addition of 1.0 g L −1 of poly-(l -lactide) powder and 1.0 g L −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 0.52 g L −1 poly(l -lactide) powder and 3.34 g L −1 cassava starch increased poly-(l -lactide)-degrading enzyme and raw starch-degrading enzyme activities up to 68.8 U mL −1 and 86.1 U mL −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 4 h. 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. Highlights: Co-production of poly (l -lactide)-degrading enzyme and raw starch-degrading enzyme was archived by Laceyella sacchari LP175. Cheap and abundant agricultural products was used for enzyme productions. Mechanisms on biodegradation of the bioplastic PLLA/TPS blend were elucidated. Application of crude enzyme could degrade 99.7% of poly-(l -lactide)/thermoplastic starch (TPS) blend within 4 h.