First Evidence of an Altitudinal Variation in the Brain Size of Triturus alpestris alpestris (Laur.) (Amphibia,Caudata, Salamandridae)

This study deals with geographical variations in brain-body weight relationships in the alpine newt, Triturus alpestris alpestris. According to the canonical axis, C.A., the mean allometry in this species is 0.473±0.03; an allometry value of 0.5 is considered to be characteristic of Caudata. No significant difference was observed between the four reduced major axes (R.M.A.) of lowland animal samples (mean value of the pooled samples, C.A. = 0.469±0.210). In contrast, between the mountain samples a significant difference exists, the R.M.A. in the sample from l'Alpe d'Huez (Isère, France) being 0.331±0.57 as compared to 0.72±0.18 in the sample from Durmitor (Montenegro, Yugoslavia). In spite of this difference, their encephalisation index (Ie) did not differ significantly, having on average a value of 118.18±8.5, against īe = 93.8±8.0 for lowland samples. A significant difference in encephalisation index between mountain and lowland alpine newts thus exists. This is probably the first observation in vertebrates of an encephalisation index increase with altitude. A biological hypothesis is proposed to explain this peculiar observation.     

Substrate conditions that influence the assays used for determining the beta-glucosidase activity of cellulolytic microorganisms

Culture filtrates from Trichoderma harzianum E58, T. reesei CL 847 and Penicillium sp. C 462 were assayed for beta-glucosidase activity using a range of substrates and sugar analysis methods. Although sugar analyses by the dinitrosalicylic acid (DNS) and Nelson-Somogyi methods gave a similar profile, when increasing concentrations of salicin were assayed, considerably higher values were obtained with the DNS assay. The salicin concentration used for the assay greatly influenced the final beta-glucosidase values with higher values obtained for T. harzianum E58 and T. reesei CL 847 at substrate concentrations of 1 mg/mL while optimum values for Penicillium sp. C 462 were obtained at substrate concentrations greater than 3 mg/mL. Low concentrations of salicin and p-nitro-phenyl-beta-D-glucopyranoside (PNPG) gave the same response as cellobiose. Cellobiose should be used at concentrations greater than 3.74 mg/mL to avoid substrate limitation of the beta-glucosidase assay.     

Production and localization of cellulases and β-glucosidase from the thermophilic fungusThielavia terrestris

Summary The enzyme production and localization ofThielavia terrestris strains C464 and NRRL 8126 were compared to determine their optimum temperature and pH for cellulase activity. High levels of intracellular -glucosidase activity were detected in the former strain. The intracellular -glucosidase of both strains were more thermostable than the extracellular enzyme; the half life ofT.terrestris (C464) endoglucanase activity at 60°C was greater than 96 hrs.     

Biological degradation of resin acids in wood chips by wood-inhabiting fungi.

Resin acids in many pulp mill effluents are primary sources of toxicity to fish. Inconsistent biological detoxification of chlorinated and nonchlorinated resin acids in secondary treatment of pulp mill effluents is a continuing source of concern. An alternative approach to effluent detoxification is to remove or modify the toxic compounds present in wood chips prior to pulping. Results from experiments in which lodgepole pine sapwood chips were inoculated with several fungal candidates indicate that the total resin acid content can be reduced by up to 67% after fungal growth. Such a treatment could be an efficient and environmentally acceptable way for deresinating wood chips and so decreasing the toxicity of pulp mill effluents.     

Lipase and esterase formation by psychrophilic and mesophilic Acinetobacter species.

Acinetobacter O16, a psychrophilic species, produced extracellular lipase (measured by hydrolysis of olive oil, tributyrin, or beta-naphthyl laurate) when grown on a complex medium (peptone plus yeast extract). Most lipase was produced during the logarithmic phase of growth. Very little cell-bound lipase was formed. These cells also produced an esterase (measured by the hydrolysis of beta-naphthyl acetate). At first, all esterase was cell bound; significant amounts appeared in the external medium late in growth. Breaking the cells did not increase cell-bound lipase activity. After breaking of the cells, most of the cell-bound lipase and esterase activity was solubilized, even after very high speed centrifugation. No appreciable amounts of these enzymes were released by osmotic shock. Lipase formation was greatly affected by nutrient conditions. Lowering either the yeast extract of the peptone content of the normal complex medium lowered or abolished lipase formation. Esterase activity was lowered to a lesser extent. Cells growing in synthetic amino acid plus vitamin medium or in acid-hydrolyzed casein produced substantial amounts of esterase but no cell-free or cell-bound lipase. However, if sodium taurocholate was added to these media, lipase was produced. Greatest production occurred if a mixture of di- and poly-peptides was also present. Taurocholate also stimulated lipase production in the normal complex medium. Adding Tween 80 or ethanol to the normal complex medium inhibited lipase production. Sodium acetate, oleic acid, olive oil, or Tween 20 added to synthetic media did not affect lipase production. The psychrophile grew more quickly at 30 degrees C than at 15 or 20 degrees C but produced more lipase at the lower temperatures. Esterase production was about the same at 20 and 30 degrees C. A mesophilic Acinetobacter species produced the same amount of lipase and esterase at 20 and 30 degrees C. The best production of lipase by the psychrophile occurred in standing cultures.     

Accumulation of an iodophilic polysaccharide during growth of Acetivibrio cellulolyticus on cellobiose

Maximum growth of Acetivibrio cellulolyticus in 1% cellobiose (w/v, added as filter sterilized solution) medium was observed after about 24h of incubation at 35°C. The metabolic end products of growth were H₂, CO₂, acetic acid, ethanol and glucose. Growth was adversely affected if cellobiose was autoclaved with the rest of the media ingredients. In the presence of an excess of cellobiose, the cells accumulated large quantities of an iodophilic polysaccharide (IPS). The maximum IPS accumulation (about 37% of the cell dry weight) was observed after about 12h growth under nitrogen-limiting conditions. Starvation of these cells anaerobically, in a pH 7.0 phosphate buffer for 10 h at 35°C, resulted in about 50% drop in the IPS. The results also indicated that A. cellulolyticus accumulated this iodophilic polysaccharide during growth on cellobiose but not during cultivation on cellulose.Abbreviation IPS iodophilic polysaccharide Issued as NRCC No. 19386     

Composition of Methanospirillum hungatii GP1 during growth on different media

Growth of Methanospirillum hungatii GP1 as determined by optical density measurement wsa comparable to growth assessed by cell dry weight, ribonucleic acid content, and deoxyribonucleic acid content. Cultivation of M. hungatii on synthetic medium containing mineral salts, vitamins, and acetic acid indicated that, on a dry weight basis, cell constituents such as protein (71%), ribonucleic acid (15.8%), deoxyribonucleic acid (1.6%), and total carbohydrate (3.2%) did not vary significantly with the growth phase. Cells grown in the synthetic medium supplemented with yeast extract and tryptone had slightly higher protein content (76%), but the concentrations of the other cell constituents were similar and did not fluctuate much during growth. Nitrogen limiting growth resulted in somewhat lower ribonucleic acid content as well as slightly higher protein content than that in cells grown in nonlimiting medium. Methanospirillum hungatii did not accumulate any of the commonly known reserve materials under nitrogen or carbon and hydrogen limiting growth.     

Influence of biomass production and detachment forces on biofilm structures in a biofilm airlift suspension reactor

The influence of process conditions (substrate loading rate and detachment force) on the structure of biofilms grown on basalt particles in a Biofilm Airlift Suspension (BAS) reactor was studied. The structure of the biofilms (density, surface shape, and thickness) and microbial characteristics (biomass yield) were investigated at substrate loading rates of 5, 10, 15, and 20 kg COD/m3. day with basalt concentrations of 60 g/L, 150 g/L, and 250 g/L. The basalt concentration determines the number of biofilm particles in steady state, which is the main determining factor for the biofilm detachment in these systems. In total, 12 experimental runs were performed. A high biofilm density (up to 67 g/L) and a high biomass concentration was observed at high detachment forces. The higher biomass content is associated with a lower biomass substrate loading rate and therefore with a lower biomass yield (from 0.4 down to 0.12 gbiomass/gacetate). Contrary to general beliefs, the observed biomass detachment decreased with increasing detachment force. In addition, smoother (fewer protuberances), denser and thinner compact biofilms were obtained when the biomass surface production rate decreased and/or the detachment force increased. These observations confirmed a hypothesis, postulated earlier by Van Loosdrecht et al. (1995b), that the balance between biofilm substrate surface loading (proportional to biomass surface production rate, when biomass yield is constant) and detachment force determines the biofilm structure. When detachment forces are relatively high only a patchy biofilm will develop, whereas at low detachment forces, the biofilm becomes highly heterogeneous with many pores and protuberances. With the right balance, smooth, dense and stable biofilms can be obtained. Copyright 1998 John Wiley & Sons, Inc.