1.
Optimization of the medium composition of a biphasic production system for mycelial growth and spore production of Aschersonia placenta using response surface methodology.
Qiu, J, Song, F, Qiu, Y, Li, X, Guan, X
Journal of invertebrate pathology. 2013;(2):108-15
Abstract
The culture media for mycelial growth and sporulation of the entomopathogenic fungus Aschersonia placenta were optimized using the response surface method (RSM). Interactions of medium components and the optimization of a biphasic production system were studied using Box-Behnken design (BBD) with three levels of three variables. Experimentation confirmed that the model developed based on RSM and BBD successfully predicted mycelia production (R(2) = 0.9336) and conidia production (R(2) = 0.9532). In the first phase, mycelial dry weight was highest (2.14 ± 0.17 g per 100ml of culture, mean±SE) when the concentrations (g/l) of glucose, vitamin B(6), and MgSO(4)·7H(2)O were 31.4, 11.5, and 0.64, respectively. In the second phase, conidia production was highest (9.31 ± 0.48 × 10(7)sporespercm(2)) after 18d of cultivation in the medium containing 33.8 g/l of millet, 1.11 g/l of KH(2)PO(4), and 0.37 g/l of MgSO(4). Mycelial and conidial yields were 3.6- and 10-fold greater, respectively, with the optimized media than with the non-optimized basal media. The results indicate that RSM and BBD methods are effective for increasing the production of A. placenta mycelia and conidia.
2.
Pretreatment of empty fruit bunch from oil palm for fuel ethanol production and proposed biorefinery process.
Tan, L, Yu, Y, Li, X, Zhao, J, Qu, Y, Choo, YM, Loh, SK
Bioresource technology. 2013;:275-82
Abstract
This study evaluates the effects of some pretreatment processes to improve the enzymatic hydrolysis of oil palm empty fruit bunch (EFB) for ethanol production. The experimental results show that the bisulfite pretreatment was practical for EFB pretreatment. Moreover, the optimum pretreatment conditions of the bisulfite pretreatment (180 °C, 30 min, 8% NaHSO3, 1% H2SO4) were identified. In the experiments, a biorefinery process of EFB was proposed to produce ethanol, xylose products, and lignosulfonates.
3.
Bioleaching of heavy metals from mine tailings by indigenous sulfur-oxidizing bacteria: effects of substrate concentration.
Liu, YG, Zhou, M, Zeng, GM, Wang, X, Li, X, Fan, T, Xu, WH
Bioresource technology. 2008;(10):4124-9
Abstract
The aim of this study was to determine the effect of substrate concentration (elemental sulfur) on remobilization of heavy metals from mine tailings by indigenous sulfur-oxidizing bacteria. Also, the variation in the binding forms of heavy metals before and after bioleaching was explored. This work showed the laboratory results of bioleaching experiments on Pb-Zn-Cu mine tailings. The results showed that 97.54% Zn, 97.12% Cu, and 44.34% Pb could be removed from mine tailings by the bioleaching experiment after 13 days at 2% w/v substrate concentration. The results also indicated that substrate concentration 2% was found to be best to bacterial activity and metal solubilization of the five substrate concentration tested (0.5%, 1%, 2%, 3%, and 5%) under the chosen experimental conditions. The bioleaching had a significant impact on changes in partitioning of heavy metals.