期刊名称：Walailak Journal of Science and Technology (WJST)
印刷版ISSN：2228-835X
出版年度：2017
卷号：14
期号：12
页码：921-939
DOI：10.14456/vol15iss6pp%p
语种：English
出版社：Institute of Research and Development, Walailak University.
摘要：Virgibacillus alimentarius LBU20907 is an efficient extracellular halophilic lipase producer. Isolate LBU20907 was identified by 16S rRNA gene sequence analysis and phenotypic identification before determining the optimal nutritional and cultural conditions for its halophilic lipase activity. Two statistical designs were used to predict the responses to varying factors: Plackett-Burman experimental design (PBD) and central composite design (CCD). The important factors affecting the halophilic lipase production were identified by 2-level PBD of 11 physicochemical parameters screened, 3 factors produced significantly positive effects. These were olive oil, CaCl 2 , and temperature. The response surface methodology (RSM) was applied to the CCD to predict the most productive levels of these 3 factors. The results predicted that a maximum halophilic lipase activity of 65.96 U mL -1 should be achieved with an olive oil concentration of 1.68 %, a CaCl 2 concentration of 0.14 g L -1 and a temperature of 39.5 °C. The predicted halophilic lipase activity in the optimized medium represented an increase of nearly 42 % compared with the predicted result of 46.50 U mL -1 in the non-optimized medium. The model was validated by subsequent experimentation at the optimized conditions. The predicted values were in agreement with the experimental values with a coefficient of determination ( R 2 ) of 0.9995. After scale-up using a 3 L laboratory fermenter, a halophilic lipase yield of 82.50 U mL -1 was effectively achieved: 77 % more than predicted to occur in the non-optimized medium. Therefore, halophilic lipase production by V. alimentarius LBU20907 can be regarded as promising attractive catalysis for several industrial applications.
其他摘要：There are many rice characteristics that contribute to the grain yield. This study aimed to characterize relationships of yield and yield components into direct and indirect effects, and to estimate the magnitude of genotypic and phenotypic variation, heritability and genetic advance. The study was conducted with 232 recombinant inbred lines (RILs) derived from a cross between low yield but good cooking quality, KDML105, and new plant type with high yield, CH1 rice variety. These lines were planted in RCBD with 3 replications. Data were collected for agronomic traits, yield components and yield. The results indicate that path coefficient analysis elucidated a positive direct effect on the number of panicles per plant (0.540) and the number of filled grains per panicle (0.510). Percentages of their direct effect were 62.11 and 74.68 %, respectively. These 2 traits demonstrate high significant value which could be used as selection criteria for yield improvement. Moreover, high values of heritability along with high genetic advance were observed for plant height, grain yield and the number of filled grains per panicle. Thus, these characters may serve as selection criteria combined with flag leaf length for improved high yield potential of rice.
