Hydrolysis of rice straw to fermentable sugars byTrichoderma enzymes

Summary ATrichoderma sp. (IMB-Tr) isolated from rice straw possessed cellulolytic and xylanolytic activity, comparable to those produced byTrichoderma reesei QM 9414 (a proven cellulolytic fungus). IMB-Tr produced 2.9 and 1.9 times, respectively, greater -glucosidase activity compared toT. reesei when grown on microcrystalline cellulose and rice straw. Percentage enzymic hydrolysis increased with increase in the sodium hydroxide concentration used in the pretreatment of rice straw and with the increase of enzyme concentration used in the hydrolysis. The extracellular enzyme fraction ofT. reesei possessed greater hydrolytic power than that of IMB-Tr. However, when a combined enzyme preparation from the two organisms was used, an appreciable degree of synergism was observed; an increase in reducing sugars up to 39% was seen. The reducing sugar produced by enzymic hydrolysis was mainly glucose, xylose and cellobiose. Fermentation of a 4.8% (w/v) sugar hydrolysate (produced by the enzymic hydrolysis of rice straw) bySaccharomyces cerevisiae produced 10.7 g/l of ethanol compared to 18.8 g/l produced by the fermentation of 4.8% (w/v) pure glucose.

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Resumen Se ha aíslado a partir de paja de arroz una cepa deTrichoderma sp. (IMB-Tr) que posee actividades celulolíticas y xilanolíticas comparables a las deTrichoderma reesei QM 9414 (un hongo probadamnete celulolítico). IMB-Tr produjo 2.9 y 1.9 veces más actividad -glucosidásica queT. reesei cuando ambos se hicieron crecer en celulosa microcristalina y en paja de arroz respectivamente. El porcentaje de hidrolisis enzimática se incrementó con el aumento en la concentración del hidróxido sódico empleado en el pretratamiento de la paja de arroz y con el aumento de la concentración enzimática utilizada en la hidrolisis. La fracción extracelular enzimática deT. reesei poseía un mayor poder hidrolítico que la de IMB-Tr, sin embargo cuando se usó un preparado enzimático combinado de ambos microorganismos se obtuvo un apreciable efecto sinérgico, observándose un incremento de hasta un 39% de los azucares reductores producidos. Estos azucares fueron principalmente glucosa, xilosa y celobiosa. La fermentación de un 4.8% (p/v) del hidrolisado azucarado (producido por la hidrolisis enzimática de la paja de arroz) porSaccharomyces cerevisiae produjo 10.7 g/l de etanol comparado a 18.8 g/l obtenidos de la fermentación de 4.8% (p/v) de glucosa pura.

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Résumé Une souche deTrichoderma sp. (IMB-Tr), isolée à partir de paille de riz, a une activité cellulolytique et xylanolytique comparable à celle deTrichoderma reesei QM 9414 (champignon cellulolytique reconnu). L'activité -glucosidase d'IMB-Tr cultivé sur cellulose micro-cristalline ou sur paille de riz est, respectivement, 2.9 et 1.9 fois plus élevée que celle deT. reesei. Le pourcentage d'hydrolyse enzymatique croit avec la concentration de la soude employée pour le pré-traitement de la paille et avec la concentration d'enzyme utilisée pour l'hydrolyse. La fraction exocellulaire de l'enzyme a une activité hydrolysante plus élevée dans le cas deT. reesei que dans celui de IMB-Tr. Cependant, si on emploie un mélange des activités enzymatiques des deux organismes, on constate une nette synergie et un accroissement des sucres réducteurs allant jusqu'à 39%. Les sucres réducteurs obtenus par hydrolyse enzymatique comprennent principalement du glucose, du xylose et du cellobiose. La fermentation parSaccharomyces cerevisiae d'un hydrolysat enzymatique de paille de riz contenant 4.8% (poids/vol.) de sucres fournit 10.7 g/l d'éthanol, au lieu de 18.8 g/l obtenus par fermentation de glucose pur à la même concentration.

     

Phospholipases as possible virulence factor in Vibrio parahaemolyticus

Phospholipase C activity was elevated in pathogenic Vibrio parahaemolyticus isolated from patients. Phospholipase A activity was more pronounced in the nonpathogenic V. parahaemolyticus strains isolated from water. Extracts of the strains containing phospholipase C and A activity but no thermostable direct haemolysin (TDH) were capable of producing lesions in guinea pig skin indicating the presence of a toxic factor other than TDH. It is suggested that the toxic factor may be phospholipase C since the purified enzyme from Clostridium perfringens produced a similar reaction in guinea pig skin.     

Survival of Vibrio parahaemolyticus in cold smoked fish

Fresh samples of mullet (Mugil cephalus) and oil sardines (Sardinella longiceps) obtained from a fish market were subjected to cold smoking. Some of the samples harboured low levels of Vibrio parahaemolyticus. After cold smoking, however, many samples showed relatively high levels of V. parahaemolyticus suggesting that a small population of naturally occuring organisms could multiply to significant levels during the process of cold smoking or during subsequent storage at room temperature. Nevertheless, smoke components were observed to exert an inhibitory effect on V. parahaemolyticus in broth. Salt concentration 1% appeared to increase the sensitivity of V. parahaemolyticus to smoke components.     

Hydrogen peroxide formation and lipid peroxidation in rat uterus—effect of hormones and vitamin E

The effect of estradiol-17β and progesterone given separately as well as in combination on the rate of hydrogen peroxide formation and lipid peroxidation in the uteri of ovariectomized rats was studied. Estradiol in 3μg dose per day per animal elicited maximum stimulatory response and progesterone (100μg), on the other hand, was without any such effect. However, progesterone given along with estradiol completely prevented the effect due to the latter. In the same way, vitamin E, a well known antioxidant was found to be extremelv effective in protecting the uterus from the highly peroxidative action of estradiol-17β.     

Studies on the partial structure of the O-antigen of Vibrio cholera Ogawa G-2102

Detailed information was obtained regarding the partial structure of the lipopolysaccharide (LPS), containing glucose, glucuronic acid, 2-amino-2-deoxy-glucose, L-glycero-D-gluco-heptose, and small proportions of L-glycero-D-manno-heptose, mannose, and galactose, isolated from Vibrio cholera Ogawa G-2102. Structures of three oligosaccharides were determined. Results of deamination experiments established the sequence of the linkages between the amino sugar and heptose residues in the O-antigenic polysaccharide.     

The influence of dietary protein on ascorbic acid metabolism in rats

1. d-Glucuronolactone reductase, l-gulonolactone oxidase, uronolactonase, dehydroascorbatase, l-gulonate dehydrogenase and l-gulonate decarboxylase have been measured in the tissues of rats fed on diets containing variable amounts of protein. Rats fed on a protein-free or a 2% casein diet for 15 days showed a marked decline in the activities of d-glucuronolactone reductase, l-gulonolactone oxidase, uronolactonase and dehydroascorbatase in the liver, and no change in l-gulonate dehydrogenase and l-gulonate decarboxylase activities in the kidney when compared with rats fed on diets containing 9%, 18% or 25% casein. Giving diets containing 60% or 88% casein to rats did not appreciably alter the activities of uronolactonase, dehydroascorbatase, l-gulonate dehydrogenase and l-gulonate decarboxylase, but inhibited considerably the activities of d-glucuronolactone reductase and l-gulonolactone oxidase in the liver, resulting in decreased synthesis of ascorbic acid. 2. Rats fed on a 25% casein diet showed maximal weight gain, higher tissue reserve of ascorbic acid and higher urinary excretion of both ascorbic acid and glucuronic acid when compared with rats fed on diets containing lower or higher amounts of protein.     

Modulation of sialic acid-binding proteins of rat uterus in response to changing hormonal milieu

A group of sialic acid binding (SAS) agglutinins has been isolated from the rat uteri at different stages [Proestrus (P), estrus (E) and diestrus (D)] of estrous cycle. Studies of biochemical properties indicate that SAS agglutinins are glycoprotein in nature having molecular weights between 28–31 Kd and microheterogenous pI. Function-based characterization revealed that inspite of the fact that all three proteins exhibit sialic acid binding property, the sialic acid binding affinities, calculated from Scatchard analysis, using 4-methylumbelliferyl sialic acid as a ligand, varied in stage specific manner (Ka:D-SAS-9.03×10⁵ M^–1, P-SAS-2.33×10⁵ M^–1, E-SAS-2.13×10⁵ M^–1). Circular dichroism spectra of these three agglutinins suggested that differences exist in the secondary structures of the proteins isolated from different stages. Removal of carbohydrate moiety by trifluoromethane sulfonic acid treatment and CNBr cleavage studies showed some homology between these proteins, however, the variation in the carbohydrate moiety was apparent from the sugar analysis data. Functionally and immunologically these proteins can be grouped as estrogenic and progestogenic SAS agglutinins.