Browsing by Author "Srisuda Hanphakphoom"

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    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
    (Elsevier Ltd, 2015) Thanasak Lomthong; Srisuda Hanphakphoom; Rangrong Yoksan; Vichien Kitpreechavanich
    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 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.
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    Enhancement of poly(L-lactide)-degrading enzyme production by Laceyella sacchari LP175 using agricultural crops as substrates and its degradation of poly(L-lactide) polymer
    (Elsevier Ltd, 2017) Thanasak Lomthong; Srisuda Hanphakphoom; Prachumporn Kongsaeree; Nantana Srisuk; Marie Guicherd; Gianluca Cioci; Sophie Duquesne; Alain Marty; Vichien Kitpreechavanich; V. Kitpreechavanich; Department of Microbiology, Faculty of Science, Kasetsart University, Bangkok, 10900, Thailand; email: fsciwck@ku.ac.th
    Optimization of the medium for poly(L-lactide) (PLLA)-degrading enzyme production in shake flask experiments was investigated using agricultural products as substrates. Cassava chips and soybean meal were the best carbon and nitrogen sources, respectively, as determined by the one-factor-at-a-time method. Enzyme production was significantly enhanced by the addition of phosphates, but was suppressed by the addition of ammonium salt. The maximum enzyme production, 65.5 U/mL, was obtained from the optimized medium consisting of 4.64 g/L cassava chips, 1.53 g/L soybean meal and 0.31 g/L PLLA powder using central composite design in the basal medium. The optimal physical factors in 3 L airlift fermenter were 50 �C, pH 7.0 and 0.5 vvm aeration rate for 18 h, yielded 94.4 U/mL. The crude enzyme was shown to be able to hydrolyze PLLA powder (91%) at 50 �C in 72 h which showed high efficiency for recycling of PLLA polymer and reducing the global environmental problem. � 2017 Elsevier Ltd