摘要:

AcinetobacterO16, a psychrophilic species, produced extracelullar lipase (measured by hydrolysis of olive oil, tributyrin, or β-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 β-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 or 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 °C than at 15 or 20 °C but produced more lipase at the lower temperatures. Esterase production was about the same at 20 and 30 °C. A mesophilicAcinetobacterspecies produced the same amount of lipase and esterase at 20 and 30 °C. The best production of lipase by the psychrophile occurred in standing cultures.

ISSN:0008-4166    

DOI:10.1139/m75-061

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The extracellular lipase(s) of the psychrophileAcinetobacterO16was studied. When the enzyme was precipitated by (NH4)2SO4and passed through a Sephadex G 200 column, two peaks of lipase activity appeared. The larger peak, which behaved like a substance of high molecular weight, being eluted in the void volume, was purified 250-fold over the crude enzyme (culture supernatant) by passage through a DEAE Sephadex column. When the enzyme was applied to a DEAE-cellulose column it could not be eluted unless it had first been treated with the detergent Triton X 100. It is suggested that lipids or phospholipids make up an important part of the molecule.The activity of the crude and partly purified enzymes was studied in relation to pH and temperature optima. Lipases from the psychrophilicAcinetobacterO16and from the mesophilicAcinetobacterO4reacted in the same way to temperature. The crude enzyme fromAcinetobacterO16was more temperature-stable than the purified enzyme.

ISSN:0008-4166    

DOI:10.1139/m75-062

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Hyaline hyphae ofPhomopsisbecome pigmented when exposed to short periods of light. Pigment was deposited in the form of melanin granules both within the cell wall and within mucilaginous excrescences that were developed irregularly over the hyphal surface. Analysis of the pigment showed it to have properties similar to that of "Dopa" melanin and to pigments previously isolated from fungal cell walls. Lysis of both hyaline and pigmented hyphal walls by means of lytic enzymes was minimal. It is suggested that the major role of melanin in this fungus is the protection of cellular organelles from harmful ionizing radiations.

ISSN:0008-4166    

DOI:10.1139/m75-063

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Isolates of the snowshoe hare subtype of California encephalitis (CE) virus from Yukon mosquitoes during 1972 and 1973 were transmitted by bites ofAedes aegyptimosquitoes after 4 to 5 weeks of extrinsic incubation at 55°F after intrathoracic injection, and the 1973 strain was transmitted after mosquitoes were fed virus and held for 3 to 4 weeks at 75°F. Antigen of a 1971 isolate of CE virus (Marsh Lake 23) was detected in salivary glands of infected mosquitoes by the immunoperoxidase technique, using highly purified antiserum before and after conjugation with horseradish peroxidase, plus the use of orthotolidine as a substitute for benzidine. Enveloped virions 45 nm in diameter were observed in thin sections of salivary glands ofCuliseta inornatamosquitoes 59 days after intrathoracic injection with the 1971 isolate, after incubation at 55°F.

ISSN:0008-4166    

DOI:10.1139/m75-064

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Streptomyces griseusS 104 was sensitive to streptomycin during exponential growth in a medium which, in the subsequent stationary phase, supported production of the antibiotic in yields above 200 μg/ml. When antibiotic production began cultures developed a tolerance toward their lethal metabolite. This was not due to an increase in pH associated with antibiotic production, since pH effects on streptomycin sensitivity inS.griseuswere in the reverse direction. However, the degree of tolerance was directly related to the amount of cell material present. Streptomycin production caused no change in the proportion of resistant variants in the population, nor did it cause the severe inhibition of protein synthesis observed in non-producing cultures exposed to the antibiotic. The lack of an effect on protein synthesis is attributed to the absence of streptomycin within the cytoplasm since soluble extracts from mycelium harvested in the production phase were inactive when bioassayed immediately after cell disruption. However, they developed antibacterial activity rapidly when heated, and more slowly when incubated at 25 °C. The addition of phosphatase inhibitors during incubation prevented the appearance of antibiotic activity, and it was concluded that a small amount of streptomycin phosphate is present in the mycelium during antibiotic production. Differences in (14C) streptomycin uptake suggested that the mycelium was appreciably less permeable to the antibiotic in the production phase than during exponential growth. However, a small amount was taken up and much of it was in the soluble fraction of disrupted cells. Bioassays showed that this14C-labeled antibiotic within the cells had been partially inactivated, suggesting that conversion of streptomycin to an inactive derivative is involved in the mechanism which protects the organism from its metabolite.

ISSN:0008-4166    

DOI:10.1139/m75-065

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The properties of succinate uptake in succinate-grownKluyveromycescells were examined. The rate of succinate transport at 15C exhibits an approximateVmaxof 1.2 μmol × h−1 × mg−1dry weight of cells and an apparentKmof 18 μM. The uptake process appears to be tightly coupled to metabolism.L-Malate, fumarate, and α-ketoglutarate were the only other dicarboxylates tested, which were found to inhibit succinate transport. The agreement between the order of inhibition of succinate transport by these dicarboxylates and their rates of uptake, as well as the competitive nature of the inhibition are all consistent with the existence of a common carrier system showing specificity for dicarboxylates of the TCA cycle. Cells transferred from succinate to glucose medium rapidly lose their ability to transport succinate. Glucose-grown cells also exhibit an inability to oxidize dicarboxylates or to use them for growth without a very long lag. The dicarboxylate uptake system, therefore, appears to be subject to a strong catabolite repression. The derepression of the succinate transport system requires the presence of succinate, as well as low concentrations of glucose.

ISSN:0008-4166    

DOI:10.1139/m75-066

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

An agar-disc method was used to compare the bacteriostatic properties of five soils with those of samples of the same soils sterilized by gamma irradiation. For three of the soils, bacteriostasis was removed either partially or entirely by sterilization. Bacteriostasis was completely restored to sterile soil by reinoculating it with natural soil. All the reinoculation treatments restored the level of bacteriostasis equally effectively, whatever the origin of the soil used as inoculum.

ISSN:0008-4166    

DOI:10.1139/m75-067

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

A previously undescribedBacillusspecies has been characterized. The organism was isolated from a blood transfusion bottle implicated in a fatal bacteriogenic transfusion reaction and has been examined from a number of different aspects to characterize it as completely as necessary to provide identification. It was placed into group 3 of the genusBacilluson the basis of its cellular morphology, the morphology of the sporangium, and the location of the spore within the cell. There are only three other species described in this group. Since the organism differed markedly from each of these, it appears to represent a new species.

ISSN:0008-4166    

DOI:10.1139/m75-068

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The pathogenic effects produced in mice by intraperitoneal (i.p.) injection of aBacillusspecies (OSU 372) are presented. This organism belongs to group 3 of the genus, and members of this group have not heretofore been shown to be pathogenic for mice even under experimental conditions. However, this organism is capable of producing a fatal involvement in doses which are not considered to be overwhelming. The mean lethal dose (LD50) of the organism for 20–25 g mice by the i.p. route is about 1 × 108bacteria/mouse. A rapid drop in body temperature along with severe dehydration were noted in infected animals, and hematologic studies indicated that leukopenia and hemoconcentration also occurred. Although a transient septicemia developed, the bacteria could not be recovered from the tissues of fatally infected mice after a certain point in time. Results presented indicate that the animals died of hypovolemic shock. A possible parallel with human bacillary infection is drawn.

ISSN:0008-4166    

DOI:10.1139/m75-069

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Aerobic flora from wet-occluded forearms of six volunteers was sampled the day before treatment, on the 3rd day when dressings were removed, and daily, when possible, for 8 days thereafter. Erythema was not present. All bacterial colonies appearing on appropriate dilution plates were identified with the aid of a replica-plating technique. Flora of each individual increased to over 104colony-forming units/cm2as a result of wet-occlusion, but counts rapidly fell by about 102units once dressings were removed. Although similar types of bacteria were found on all subjects, the composition of each individual's flora during the recovery response appeared to be unique. Enterobacteriaceae were found on half the subjects withEnterobacter aerogenesbeing the most successful colonizer. Besides the expected presence of Baird-ParkerStaphylococcussubgroup II, high numbers of subgroup IV and some colonies of subgroup III were also observed. Almost all cutaneous diphtheroids were lipophilic and lipolytic.

ISSN:0008-4166    

DOI:10.1139/m75-070

出版商:NRC Research Press    

年代:1975

数据来源: NRC