Enzymatic Pretreatment Coupled with the Addition of p-Hydroxyanisole Increased Levulinic Acid Production from Steam-Exploded Rice Straw Short Fiber.

Levulinic acid production, directly from lignocellulosic biomass, resulted in low yields due to the poor substrate accessibility and occurrence of side reactions. The effects of reaction conditions, enzymatic pretreatment, and inhibitor addition on the conversion of steam-exploded rice straw (SERS) short fiber to levulinic acid catalyzed by solid superacid were investigated systematically. The results indicated that the optimal reaction conditions were temperature, time, and solid superacid concentration combinations of 200 °C, 15 min, and 7.5 %. Enzymatic pretreatment improved the substrate accessibility to solid superacid catalyst, and p-hydroxyanisole inhibitor reduced the side reactions during reaction processes, which helped to increase levulinic acid yield. The levulinic acid yield reached 25.2 % under the optimal conditions, which was 61.5 % higher than that without enzymatic pretreatment and inhibitor addition. Therefore, enzymatic pretreatment coupled with the addition of p-hydroxyanisole increased levulinic acid production effectively, which contributed to the value-added utilization of lignocellulosic biomass.

[Genetic polymorphism of 5 short tandem repeat loci in Hui population in Ningxia area].

OBJECTIVE: To analyze the genetic polymorphism of 5 short tandem repeat(STR) loci in Hui population in Ningxia area. METHODS: The genetic polymorphisms of five selected STR loci(D11S1984, D14S306, D14S617, D17S1290 and D19S433) in chromosomes 11, 14, 17 and 19 in 144 unrelated individuals in Hui population in Ningxia area were analyzed by PCR amplification, denaturing polyacrylamide gel electrophoresis(PAGE) and silver staining. RESULTS: 10, 8, 11, 13 and 8 alleles, 30, 25, 33, 40 and 23 genotypes of the 5 STR loci in Hui population in Ningxia were detected. The measured values of the heterozygosity of the 5 STR loci were 0.8413, 0.8033, 0.8331, 0.8369 and 0.7703; of the polymorphism information content were 0.8217, 0.7746, 0.8121, 0.8174 and 0.7332; of the discrimination power (DP) were 0.9516, 0.9257, 0.9611, 0.9660 and 0.9135. The calculated discrimination power was 0.9999995. The measured values of paternity exclusion were 0.7046, 0.6367, 0.6911, 0.7012 and 0.5801; the calculated paternity exclusion was 0.9958. The genotype distributions were in accordance with Hardy-Weinberg equilibrium. CONCLUSION: The 5 STR loci have better polymorphism in Hui population in the Ningxia area, and thus could serve as useful markers for population genetics research and for individual identification and paternity test in forensic medicine.