Browsing by Author "Rangrong Yoksan"

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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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    High Loading Degradation of Poly(lactide)/Thermoplastic Starch Blend Film Using Mixed-Enzymes Produced by Fed-Batch Culture of Laceyella sacchari LP175
    (Springer Science and Business Media B.V., 2022) Thanasak Lomthong; Srisuda Samaimai; Rangrong Yoksan; Sukhumaporn Krajangsang; Vichien Kitpreechavanich; V. Kitpreechavanich; Department of Microbiology, Faculty of Science, Kasetsart University, Bangkok, 10900, Thailand; email: fsciwck@ku.ac.th
    Purpose: Co-production of poly(l-lactide) (PLLA)-degrading enzyme and raw starch-degrading enzyme (RSDE) was investigated using a fed-batch culture of Laceyella sacchari LP175 in a 10.0ÊL airlift fermenter. Agricultural products were used as substrates for production of enzymes to degrade the poly(lactide)/thermoplastic starch blend film at high concentration. Methods: Fed-batch culture was performed in a 10.0ÊL airlift fermenter for co-production of PLLA-degrading enzyme and RSDE by L. sacchari LP175. Parameters affecting PLA/thermoplastic starch (TPS) blend film at high loading (100Êg/L) degradation were optimized using response surface methodology (RSM) with a central composite design (CCD) at 50Ê¡C for 24Êh. Results: Maximum enzyme production of PLLA-degrading enzyme and RSDE at 91.6 ± 7.21 and 120.1 ± 9.33 U/mL, respectively, were obtained when incubated at 50Ê¡C for 42Êh after adding raw cassava starch (3.34Êg/L) and PLA powder (0.52Êg/L) at 30Êh of cultivation. The optimum conditions for degradation (92.23%) from the model were enzyme concentration at 0.6% (w/v), time to add CaCO3 3Êh after digestion and 0.2ÊM of Tris-HCl buffer (pH 9.0) in the shaking flask scale with a 95% significance level (p < 0.05). These conditions gave the highest degradation at 90.65 ± 4.03% from the actual experimental. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) revealed the mixed enzymes produced by L. sacchari LP175 hydrolyzed PLA/TPS blend film at 50Ê¡C. Conclusions: Results indicated the feasibility of producing mixed enzymes by L. sacchari LP175 and hydrolysis of PLA/TPS blend film at high concentration to reduce waste accumulation through biotechnological processes. Graphical Abstract: [Figure not available: see fulltext.] © 2021, The Author(s), under exclusive licence to Springer Nature B.V.