An enzyme coimmobilized with a microorganism: the conversion of cellobiose to ethanol using beta-glucosidase and Saccharomyces cerevisiae in calcium alginate gels

The efficiency of beta-glucosidase and Saccharomyces cerevisiae in directly converting cellobiose to ethanol was studied for various combinations of the two catalytic species, both free and immobilized, in order to elucidate the advantages of using a coimmobilized system. The coimmobilized preparation was superior to a combination of separately immobilized biocatalysts. However, in this preparation, one-half the enzyme activity was lost within a week when incubated at the operational temperature in the absence of substrate. In continuous experiments, an 80% conversion of cellobiose to ethanol was obtained using the coimmobilized preparation, compared to 40% using separately immobilized biocatalysts when applying a dilution rate of 0.1 h(-1) in a packedbed reactor. The immobilized biocatalysts showed no decline in productivity during two weeks of continuous operation.     

The influence of a fall fumigation with ozone on the stomatal behavior of spruce and fir

Summary Clonal stock (grafts of 15-, 50-, and 100-year-old trees) of spruce (Picea abies (L.) Karst.) and fir (Abies alba Mill.) was exposed either to 150 ppb ozone (300 gm^-3) during 9 daylight hours or to carbon-filtered air on 35 days between 29 August and 21 October 1983. At the end of the fumigation the trees did not exhibit any visible signs of injury. Transpiration and leaf conductance in light and darkness, measured with a Licor porometer, revealed, however, stomatal sluggishness and — in spruce-increased transpiration.     

Comparison of peptidase activities in some fungi pathogenic to arthropods

Peptidases, highly specific toward several synthetic chromogenic peptides, were found in the mycelia of four arthropod pathogenic fungi: Aphanomyces astaci, Beauveria bassiana, Metarrhizium anisopliae, and Paecilomyces farinosus. A. astaci peptidases had high hydrolyzing activities toward most of the peptides, especially those with arginine in the P1 position, while those of B. bassiana and P. farinosus readily hydrolyzed peptides with valine and arginine, as well as proline and tyrosine in the P2 and P1 positions, respectively. The hydrolyzing capacities of M. anisopliae peptidases were similar to A. astaci, but showed lower specific activities. Casein or azocoll was only hydrolyzed by A. astaci peptidases. B. bassiana and M. anisopliae had a very low hydrolyzing capacity toward casein and could not degrade azocoll. P. farinosus had no hydrolyzing activity toward casein or azocoll. Only peptidases from the crayfish pathogen A. astaci could degrade the crayfish cuticle. The peptidase preparations of A. astaci and B. bassiana hydrolyzing MeO-Suc-Arg-Pro-Tyr-pNA or Bz-Phe-Val-Arg-pNA were of the serine type. The possible importance of peptidase activity of arthropod pathogenic fungi in the infection process is discussed.     

Growth and development of immature life stages ofPropylaea 14-punctata L. andCoccinella 7-punctata L. [Col.: Coccinellidae] simulated by the metabolic pool model

The conversion of aphid prey tissue (Acyrthosiphon pisum Harris) into predator biomass (immature life stages ofPropylaea 14-punctata L. andCoccinella 7-punctata L.) is calculated by plotting weight gain against assimilation (i.e. consumption minus egestion). This concept is added to the metabolic pool model byGutierrez et al. (1981) that enables the simulation of growth and development of a predator on a physiological basis. Physiological time is expressed in daydegrees above lower development thresholds for both species. Visual examination of observed and calculated values showed that the model satisfactorily describes the growth patterns of the above predators.      

The Electrical Conductivity of Bovine Milk in Mastitis Diagnosis

The electrical conductivity (EC) of milk is mainly a function of the electrolyte concentration in the milk and therefore raised in mastitis. The present investigation was aimed at elaborating, if possible, a diagnostic model for screening purposes based on EC determinations and consistent with the diagnostic procedures and interpretations commonly used in laboratory milk diagnosis in the Nordic countries (Klastrup 1975). According to this diagnosis (here called reference diagnosis) cell numbers above 300,000/ml (cell count or the corresponding CMT-score) in foremilk quarter samples during the main part of the lactation period and significantly above the lowest value on within-udder comparison during late lactation are considered indicative of mastitis and bacteriological examinations are made when called for.     

Ultrastructure and Host Specificity of Bacteriophages of Streptococcus cremoris, Streptococcus lactis subsp. diacetylactis, and Leuconostoc cremoris from Finnish Fermented Milk "Viili"

"Viili," a fermented milk product, has a firm but viscous consistency. It is produced with traditional mesophilic mixed-strain starters, which have various stabilities in dairy practice. Thirteen morphologically different types of phages were found in 90 viili samples studied by electron microscopy. Ten of the phage types had isometric heads with long, noncontractile tails, two had elongated heads with long, noncontractile tails, and one had a unique, very long elongated head with a short tail. Further morphological differences were found in the tail size and in the presence or absence of a collar, a baseplate, and a tail fiber. To find hosts for the industrially significant phages, we examined the sensitivities of 500 bacterial isolates from starters of the viili. Seven of the phages attacked Streptococcus cremoris strains, three attacked S. lactis subsp. diacetylactis strains, and four attacked Leuconostoc cremoris strains. Some phages differed only in their host specificity. Hosts were not found for 4 of the 13 morphological types of phages.     

Mutants ofStreptomyces hygroscopicus deregulated in amylase and α-glucosidase formation

Summary Two mutants, M36 and M39, of turimycin-producingS. hygroscopicus JA 6599/PR1 obtained by directed selection in a chemostat displayed altered pattern of amylase and -glucosidase production as revelaed by both constitutive enzyme formation and higher enzyme levels.     

Serolis luethjei n.sp., a new isopod crustacean from the Weddell Sea

Summary The spatial distribution and size-dependence of oxygen consumption (respiration) and production by microplankton in near surface waters of the Canadian Arctic were measured during summer, 1983. High oxygen flux rates (consumption and production) were observed near surface (upper 20–30 m) and were generally associated with high phytoplankton biomass (chlorophyll a) levels. A substantial portion of the respiration (>50%), however, was below the euphotic zone. Integrated oxygen fluxes (0–100 m) were approximately in balance (i.e., net oxygen production 0) at most locations sampled. In general, oxygen fluxes were higher than have been observed in the Southern Ocean but in the same range as found in temperate coastal waters. Size-fractionation studies showed that most (>60%) of the oxygen production and phytoplankton biomass (chlorophyll a) were associated with organisms greater than 35 m. On the other hand, more than 70% of the respiration was associated with organisms less than 35 m; on average, more than 50% of the respiration was associated with organisms less than 1 m. These results are consistent with theoretical studies and with experimental observations from temperate waters.     

Light-temperature interactions in the control of photosynthesis in Antarctic phytoplankton

Summary During October/November 1983 photosynthetic responses of natural phytoplankton from the Scotia Sea and Bransfield strait to light and temperature were examined in incubators. Both assimilation numbers at saturating light levels and the slopes of the light-limited portions of the photosynthesis versus irradiance curves were smaller than in algae from lower latitudes. However, both parameters increased significantly with rising temperatures. Light-saturated photosynthesis on the average exhibited a Q₁₀-value of ca. 4.2 between-1.5°C and +2°C. Light-limited photosynthesis between-1.5°C and +5°C rose at a rate corresponding to a Q₁₀-value of roughly 2.6. Above +5°C, temperature enhancement of both light-saturated and light-limited photosynthetic rates was minimal or absent. Our results suggest that under extremely low temperatures light-limited photosynthetic rates become temperature-dependent due to changes in maximum quantum yields.