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Validamycin A (Val-A) is produced by Streptomyces as a secondary metabolite with wide agricultural applications of controlling rice sheath blight, false smut and damping-off diseases. The effect of alkaline pH shock on enhancing Val-A production and its mechanism were investigated. A higher yield of Val-A was achieved by NaOH shock once or several times together with faster protein synthesis and sugar consumption and alkaline pH shock can increase Val-A production by 27.43%. Transcription of genes related to amino acid metabolism, carbon metabolism and electron respiratory chain was significantly up-regulated, accompanied by the substantial increase of respiratory activity and glutamate concentration. Val-A production was promoted by a series of complex mechanisms and made a response to pH stress signal, which led to the enhancement of glutamate metabolism and respiration activity. The obtained information will facilitate future studies for antibiotic yield improvement and the deep revealment of molecular mechanism., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

In this study the effect of different particle sizes of inorganic suspended solids (ISS) on the ISS accumulation in an activated sludge system was investigated. The volume mean particle diameters (Dv) of ISS were 26, 73, 106, 165, and 210 μm. There are four fates of ISS in an activated sludge system: (1) suspending in the activated sludge, (2) depositing at the bottom of the reactors, (3) discharged from the reactors via excess sludge, and lastly (4) discharged from the reactors via effluent. The accumulated ISS in the bioreactor was unevenly distributed. Based on the accumulation proportion of ISS in bioreactor, an ISS accumulation model was established, from which the ISS accumulation concentration and the MLVSS/MLSS could be predicted. The proportion of ISS suspending in activated sludge was 0.22, 0.21, 0.042 and 0.031. The proportion of ISS depositing at the bottom of bioreactors was 0.31, 0.47, 0.75, 0.76 and 0.92., (Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.)

The effect of ethanol on the production of the important agro-antibiotic validamycin A (Val-A) in medium containing agricultural by-products was investigated. Under the optimal condition of ethanol addition, the maximal Val-A production titer reached 18 g/L, which increased by 60% compared to the control. To provide an insight into cell response to ethanol, the intracellular reactive oxygen species (ROS), gene transcription and enzyme activity were determined. Intracellular ROS as the molecular signal was increased in the ethanol condition. Global regulators afsR and glnR were involved in regulation of Val-A biosynthesis, and the transcription of eight Val-A structural genes was enhanced. The activity of glucose-6-phosphate dehydrogenase (G6PD) was enhanced while glyceraldehyde 3-phosphate dehydrogenase (GAPDH) was inhibited. A signal transduction cascade from cell signal response to activated transcription of Val-A biosynthetic genes and enhanced antibiotic production is proposed. The information can be helpful for the improvement of large-scale fermentation., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

A comparative study on the composition, biodiesel production and fuel properties of non-edible oils from Euphorbia lathyris L. (EL), Sapium sebiferum L. (SS), and Jatropha curcas L. (JC) was conducted. Under optimal conditions, the FAME content and yield of the three oils were greater than 97.5 wt.% and 84.0%, respectively. The best biodiesel was produced from EL due to its high monounsaturation (82.66 wt.%, Cn: 1), low polyunsaturation (6.49 wt.%, Cn: 2, 3) and appropriate proportion of saturated components (8.78 wt.%, Cn: 0). Namely, EL biodiesel possessed a cetane number of 59.6, an oxidation stability of 10.4 h and a cold filter plug point of -11 °C. However, the cetane number (40.2) and oxidative stability (0.8 h) of dewaxed SS kernel oil (DSSK) biodiesel were low due to the high polyunsaturation (72.79 wt.%). In general, the results suggest that E. lathyris L. is a promising species for biodiesel feedstock., (Copyright © 2010 Elsevier Ltd. All rights reserved.)