摘要:

The addition of H2(10% by volume) stimulated acetylene reduction associated with excised roots, decapitated plants, and intact plants of rice grown in a continuously flooded field. Excised roots showed H2-uptake activitiy. Stimulation of N2fixation by H2in association with field-grown decapitated rice plants was confirmed by15N2incorporation.

ISSN:0008-4166    

DOI:10.1139/m85-094

出版商:NRC Research Press    

年代:1985

数据来源: NRC

摘要:

NH4Cl in a Tris–HCl buffered solution inhibited chlamydospore production in germinated macroconidia ofFusarium oxysporum. KCl, CaCl2, and buffer solutions at higher concentrations were also inhibitory but to a lesser extent. At fixed concentrations of NH4Cl and KCl mixed at different ratios, chlamydospore production decreased with increasing concentrations of. This effect was stronger at pH 8.5 than at pH 7.5, suggesting that NH3is the active component. In conclusion, both NH3and high ion concentrations can be inhibitory to the production of chlamydospores in salt solutions. No qualitative differences were found between chlamydospores formed at different concentrations of ammonia.

ISSN:0008-4166    

DOI:10.1139/m85-095

出版商:NRC Research Press    

年代:1985

数据来源: NRC

摘要:

3-O-Methyl-D-glucose and 3-O-ethyl-D-allose cause an increase in growth rate of two dextranase-producingPenicilliumspecies which is concomitant with an increase in amino acid uptake. In contrast, 3-O-ethyl-D-glucose and 3-O-methyl-D-allose have no effect on growth and inhibit uptake ofL-glutamic acid. These results indicate that considerable specificity is involved in the response ofPenicilliumsp. toO-alkylated sugars and someO-alkylated sugars may reduce production time of extracellular enzymes.

ISSN:0008-4166    

DOI:10.1139/m85-096

出版商:NRC Research Press    

年代:1985

数据来源: NRC

摘要:

The serological relationships among 55 strains ofRhizobium phaseoliof diverse geographical origin were examined by direct immunofluorescence. Five clear-cut serogroups and a minimum of 11 somatic antigenic determinants were detected among 42 strains using 11 fluorescent antibodies. At least a sixth serogroup exists to account for the remaining 13 unreactive strains. Serogroups 1 and 2 comprised a large number of strains (15 and 21, respectively), whereas serogroup 3 comprised only 4 strains and serogroups 4 and 5 a single strain each. These findings attest to a high degree of antigenic diversity as well as a high incidence of certain antigenic determinants in the collection ofR.phaseoliexamined. As a consequence, choice candidates for ecological studies would be strains endowed with a distinctive antigenic make-up as in serogroups 4 and 5.

ISSN:0008-4166    

DOI:10.1139/m85-097

出版商:NRC Research Press    

年代:1985

数据来源: NRC

摘要:

The enzyme-linked immunosorbent assay (ELISA) was used to detectRhizobiumsp. in the "cowpea" group andR.japonicumboth in culture and from nodules of glasshouse and field-grown plants. Double antibody sandwich (direct ELISA) and indirect ELISA were found to be equally sensitive in detecting rhizobia under controlled laboratory conditions. It was found that nodules preserved by freezing or drying over silica gel were equally good. No loss in sensitivity was detected when nodules were crushed directly in the microplates.

ISSN:0008-4166    

DOI:10.1139/m85-098

出版商:NRC Research Press    

年代:1985

数据来源: NRC

摘要:

Candida utiliscells constitutively contain an acetate-insensitive intracellular trehalase (α,α-trehalose glycohydrolase; EC 3.2.1.28) whose activity is maximal during exponential growth. Cells grown on glucose, sucrose, or ethanol as carbon source show decreased levels of this trehalase activity as the cultures enter the stationary phase. The enzyme activity from stationary phase cells can be restored to the levels present in growing cells by preincubation of the cell extracts with adenosine 3′,5′-cyclic monophosphate and adenosine 5′-triphosphate.In vitroactivation is also accomplished by addition of the catalytic subunit of a protein kinase preparation and adenosine 5′-triphosphate. The enzyme activity is enhancedin vivoby the presence of glucose or fluoride. Treatment of the trehalase with phosphatase results in a substantial loss of trehalase activity. Both activated and nonactivated trehalases show similar properties (Km = 1.01 × 10−2 M) and seem to be due to an enzyme with a molecular weight of 280 000. The data obtained are consistent with a regulatory model involving phosphorylation and dephosphorylation of the enzyme to control trehalase activity. In addition, another trehalase is present in this yeast whose activity is markedly inhibited by acetate.

ISSN:0008-4166    

DOI:10.1139/m85-099

出版商:NRC Research Press    

年代:1985

数据来源: NRC

摘要:

One alkalophilicBacillussp. strain C-125 (FERM No. 7344) was isolated from soil. From this organism, two types of xylanases, designated xylanase A and xylanase N, were purified by an ammonium sulfate precipitation followed by Biogel P-30 gel filtration, DEAE-cellulose chromatography, and Sephadex G-75 gel filtration. The molecular weights of xylanase A and N were estimated as 43 000 and 16 000, respectively. Immunological experiments indicated that xylanase A and xylanase N were entirely different protein molecules. Xylanase N was most active at pH 6.0–7.0, but xylanase A had a very broad pH activity curve (pH 6–10) and was still active even at pH 12.0. The maximum hydrolysis of xylan by the enzymes was about 25%. Both enzymes split xylan and yielded xylobiose and higher oligosaccharides but could hydrolyze neither xylobiose nor xylotriose. Trans xylosidation activities were detected in both enzymes.

ISSN:0008-4166    

DOI:10.1139/m85-100

出版商:NRC Research Press    

年代:1985

数据来源: NRC

摘要:

A novel 5′-nucleotidase previously described in halophilicVibrio costicolawas detected in marineVibrioandPhotobacteriumstrains. The enzyme of marine bacteria was similar in its properties to the 5′-nucleotidase ofVibrio costicola; it was outwardly oriented in the cytoplasmic membrane and dephosphorylated nucleoside 5′-tri-, di-, and mono-phosphates to respective nucleosides before uptake. The enzyme in marine strains was immunologically cross-reactive with the antibody raised against the purified 5′-nucleotidase ofVibrio costicola. The uptake of the products of ATP hydrolysis was studied inVibrio harveyi, and it was shown that both adenosine and inorganic phosphate released upon the action of 5′-nucleotidase were rapidly taken up by the cell.

ISSN:0008-4166    

DOI:10.1139/m85-101

出版商:NRC Research Press    

年代:1985

数据来源: NRC

摘要:

The green alga,Ankistrodesmus braunii(Naeg.), was found to possess a biphasic transport system forD-glucose. The high affinity component of the system had aVmaxof 1.2 × 10−7 pmol∙cell−1∙min−1and a specific transport constant (Kt) of 7.7 nMglucose. The low-affinity component had aVmaxof 10.8 × 10−4 pmol∙cell−1∙min−1at aKtof 16.2 μMglucose. These kinetic values indicate that the alga could compete successfully with bacteria for glucose in natural waters.Ankistrodesmus brauniialso grew heterotrophically on 0.1 mMglucose with a doubling time of 31.4 h. The growth rate was shown to correspond with the transport rate when an excretion rate of 3.5% and a respiration rate of 48% of the transported glucose were con

ISSN:0008-4166    

DOI:10.1139/m85-102

出版商:NRC Research Press    

年代:1985

数据来源: NRC

摘要:

Cellular ATP concentrations from six commercial cheddar cheese starter cultures propagated in skim milk under varying growth conditions were estimated. High correlations (r ≥ 0.98) were obtained between cellular concentrations from a specific culture and its corresponding plate counts at various phases of growth. However, major discrepancies were noticed in ATP concentrations from one starter culture to another at similar growth stages: no significant correlation could be found between ATP concentrations and corresponding plate counts when data from all six starter cultures were pooled. No significant correlation could be obtained for the same starter culture propagated under varying growth conditions.[Translated by the journal]

ISSN:0008-4166    

DOI:10.1139/m85-103

出版商:NRC Research Press    

年代:1985

数据来源: NRC