Prasit Jaisil

Sorbitol required for cell growth and ethanol production by Zymomonas mobilis under heat, ethanol, and osmotic stresses.

BackgroundDuring ethanol fermentation, the ethanologenic bacterium, Zymomonas mobilis may encounter several environmental stresses such as heat, ethanol and osmotic stresses due to high sugar concentration. Although supplementation of the compatible solute sorbitol into culture medium enhances cell growth of Z. mobilis under osmotic stress, the protective function of this compound on cell growth and ethanol production by this organism under other stresses such as heat and ethanol has not been described yet. The formation of sorbitol in Z. mobilis was carried out by the action of the glucose-fructose oxidoreductase (GFOR) enzyme which is regulated by the gfo gene. Therefore, the gfo gene in Z. mobilis was disrupted by the fusion-PCR-based construction technique in the present study, and the protective function of sorbitol on cell growth, protein synthesis and ethanol production by Z. mobilis under heat, ethanol, and osmotic stresses was investigated.ResultsBased on the fusion-PCR-based construction technique, the gfo gene in Z. mobilis was disrupted. Disruption of the Z. mobilis gfo gene resulted in the reduction of cell growth and ethanol production not only under osmotic stress but also under heat and ethanol stresses. Under these stress conditions, the transcription level of pdc, adhA, and adhB genes involved in the pyruvate-to-ethanol (PE) pathway as well as the synthesis of proteins particularly in Z. mobilis disruptant strain were decreased compared to those of the parent. These findings suggest that sorbitol plays a crucial role not only on cell growth and ethanol production but also on the protection of cellular proteins from stress responses.ConclusionWe showed for the first time that supplementation of the compatible solute sorbitol not only promoted cell growth but also increased the ethanol fermentation capability of Z. mobilis under heat, ethanol, and osmotic stresses. Although the molecular mechanism involved in tolerance to stress conditions after sorbitol supplementation is still unclear, this research has provided useful information for the development of the effective ethanol fermentation process particularly under environmental conditions with high temperature or high ethanol and sugar concentration conditions.

Repeated-batch ethanol fermentation from sweet sorghum juice by free cells of Saccharomyces cerevisiae NP 01

-1 of total sugar without nutrient supplement could be used as the low-cost IP medium instead of the typical IP medium or yeast extract malt extract (YM) medium. Ethanol production from the SSJ (total soluble solids of 24 °Bx) by the inoculum of Saccharomyces cerevisiae NP 01 in batch and repeated-batch fermentations was then investigated. The fermentations were carried out under static condition in 500 ml air-locked Erlenmeyer flasks at 30°C and the initial yeast cell concentration was 1×10 8 cells ml -1 . In the batch fermentation, the concentration ( P), productivity ( Qp) and yield ( Yp/s ) of ethanol were 110.09 ± 0.81 g l

Callus induction, regeneration and transformation of sugarcane ( Saccharum officinarum L.) with chitinase gene using particle bombardment

Streptococcus suis is an important swine and human pathogen, and it has presented a considerable challenge to the global public health community. Dominguez-Punaro et al. (2007) showed that two strains of mice were differentially susceptible to S. suis . The attainment of information on the differential expression of host response genes following S. suis infection is relevant to the understanding of the molecular mechanism of this disease. The intent of this study was to select and isolate differentially expressed genes from A/J and C57BL/6 mice that are associated with the host response to S. suis infection. These baseline data will allow for the screening and cloning of specific resistance genes, and further our understanding of the molecular mechanism of S. suis infection. Eightweek- old C57BL/6 and A/J mouse were infected with S. suis serotype 2, a 200-μL volume of a bacterial suspension (1 × 10 8 CFU/mL) was administrated by intraperitoneal injection to the mice, and cDNA subtraction libraries were constructed by suppression subtraction hybridization (SSH). Genes involved in immune function, such as lysozyme, interferon-active protein, macrophage activation 2-like protein, complement component-3 and Ly108 protein were up-regulated in the spleen of C57BL/6 mice to a greater extent than they were in the spleen of A/J mice, subsequent to infection with S. suis serotype 2. Interestingly, we observed that several splenic signaling factors associated with phospholipid metabolism were up-regulated to a greater extent as well in C57BL/6 mice than they were in A/J mice following infection with S. suis serotype 2. These data suggest that phospholipid metabolism may be involved in the host defense response to S. suis invasion, thereby contributing to the organism’s overall immune response to this pathogen. Key words : Streptococcus suis serotype 2, suppression, subtractive hybridization, differentially expressed genes, mouse spleen.

Comparative proteomic analysis of leaves, leaf sheaths, and roots of drought-contrasting sugarcane cultivars in response to drought stress

A better understanding of drought response proteins may improve our understanding of the mechanisms underlying drought tolerance in sugarcane. In this research, drought-tolerant (K86-161) and drought-sensitive (B34-164) sugarcane cultivars were grown and exposed to drought stress. The changes in protein expression in leafs, leaf sheaths and roots were analyzed using proteomics techniques. Proteins that responded to drought in both cultivars could be classified into four major categories, including energy and metabolism, photosynthesis, antioxidant, and defense protein. Interestingly, an increased abundance of fructose-bisphosphate aldolase under drought was observed in all three organs of K86-161. Elevated expression of oxygen-evolving enhancer protein was also found in leaves and leaf sheaths of K86-161, when compared with their controls. Additionally, SOD was abundant in the leaves and roots of K86-161. Importantly, the expression level of these proteins decreased in B34-164 under drought stress. These contrasting results suggest that these proteins were inhibited by drought stress in the drought-sensitive cultivar. This proteomic research is the first to combine analyses of leaves, leaf sheaths and roots in sugarcane, which may enhance our understanding of drought responses at the molecular level and lead to selective breeding for enhanced drought tolerance.

Performance and Stability for Yield and Component Traits of Elite Sugarcane Genotypes Across Production Environments in Thailand

High and stable yield across varying environments are desirable traits of crop cultivars. The objectives of this study were to assess the performance and stability for cane yield, sugar yield and related component traits of elite sugarcane genotypes across the range of production environments in Thailand, and to identify the traits that contributed to high yield performance and stability. Data from multi-environment trials of ten sugarcane genotypes conducted at nine locations covering different sugarcane growing regions of the country for two crop-classes were used. Performance and stability of the test genotypes were evaluated by the GGE biplot method based on sugar yield, cane yield, commercial cane sugar (CCS), stalk number, stalk length, stalk weight and stalk diameter. Khon Kaen 3 and Kps94-13 were identified as the most superior genotypes for sugar yield, having consistent performance and stability of sugar yield across the two crop-classes and also ranking high in cane yield and CCS, while K88-92 was the most superior genotype in cane yield. The relative performance and stability of genotypes for plant crop and ratoon crop were consistent for all traits except stalk weight. Sugar yield was largely determined by cane yield, while stalk number and stalk length were the major factor determining the superiority of cane yield in the present study. Medium stalk diameter was also found to be associated with high CCS. These three traits could be used as indicators for selection for high and stable sugar yield in sugar cane.

Application of LW7 marker for identification of progenies with male sterility gene in sweet sorghum population

Verificou-se o uso do marcador LW7 para identificacao de linhas mantenedoras B e restauradoras R em sorgo granifero e doce e para identificacao de linhas mantenedoras B nas geracoes F2, RC1F2 e RC2F2. Vinte e cinco acessos de sorgo foram avaliados e o marcador LW7 identificou corretamente aqueles que possuem o gene de macho-esterilidade (rf4) como Suphan Buril e 03B, os quais nao mostraram a banda de 779 pb. O cruzamento entre Suphan Buri1 e uma linha macho-esteril (A) 03A resultou macho-esteril, confirmando a utilidade do marcador em programas de melhoramento. Linhas B em geracoes F2, RC1F2 e RC2F2 foram identificadas pelo marcador LW7 e a taxa de segregacao de 3:1 para fertilidade e macho-esterilidade nas progenies das tres geracoes apoiaram o modelo de segregacao Mendeliana de um gene. O uso da selecao assistida por marcador foi bem sucedido para o desenvolvimento de linhas de sorgo sacarino com macho-estereis.