The nitrogenase enzyme activity of free-living, microaerobically grown Rhizobium japonicum 61A76, USDA 83 and Rhizobium sp. 32H1 was depressed by ammonia, several individual amino acids and complex nutrients like casamino acids and yeast extract when added to cultures growing on glutamate or aspartate. The extent of depression of nitrogenase activity by these nitrogen-containing compounds was concentration-dependent but varied with the Rhizobium strain. Higher depression of activity with ammonia was noted in strains which had better uptake of ammonia under the microaerobic conditions that are essential for nitrogenase synthesis in rhizobia.
The positions of double bonds in cellular monounsaturated fatty acids isolated from six representative strains of corynebacteria were determined by mass fragmentography. Hexadecenoic acid from Corynebacteriumglutamicum CNF 016 and Brevibacterium ammoniagenes CNF 096 was principally the Δ7 isomer, while octadecenoic acid from these organisms was the Δ9 isomer. The monounsaturated fatty acids in Corynebacterium diphtheriae CNF 017 and Corynebacterium xerosis CNF 010 consisted mainly of the Δ9 isomers. In Corynebacterium equi CNF 002 and Corynebacterium fascians CNF 006, hexadecenoic acid was a mixture of Δ9 and Δ10 isomers, while octadecenoic acid was composed principally of the Δ9 isomer. The results suggest that the profiles of double bond location in unsaturated fatty acids are very useful for the taxonomic characterization of corynebacteria.
The lys+ gene was detected as the smallest DNA. fragment (2.5×106 dalton) among the several genetic markers tested from EcoRI-cleaved B. subtilis chromosomal DNA preparations by agarose gel electrophoresis followed by identification with DNA mediated transformation experiments. The DNA fragment retaining the lys+ gene was cloned in a B. subtilis temperate phage ρ11 using the prophage transformation method. The molecular weight of the genome of the constructed specialized transducing phage (ρ11dlys+) was estimated to be 72-73×106. The phage was cross-reacted with an antiserum against ρ11 phage particles. The physical map of ρ11dlys+ DNA using SalI and BamHI was quite different from that of ρ11 DNA. ρ11dlys+ did not carry theρ11-coded thymidyrate synthetase gene.
The relationships between strains of the genera Cryptococcus, Filobasidiella, Filobasidium, and related microorganisms were studied comparing enzymes electrophoretically. In the genus Cryptococcus, seven species out of eleven and five varieties out of six had considerable variations in their enzymatic patterns. They were: Cryptococcus albidus var. albidus, C. albidus var. diffluens, C. hungaricus, C. luteolus, C. skinneri, C. laurentii var. laurentii, C. laurentii var. flavescens, C. laurentii var. magnus, C. macerans, and C. ater. Certain strains of C. albidus var. albidus and C. kuetzingii produced identical enzymatic patterns. The different serotypes of the two species of Filobasidiella were distinguishable by their enzymatic patterns. Leucosporidium scottii strains were considered to comprise at least two species. C. flavus and Rhodotorularubra produced similar enzymatic patterns. Moreover, C. macerans and one strain of Rhodotorula glutinis showed similar enzymatic patterns.
Bacteroides multiacidus fermented glucose to lactate and succinate as major products and produced small amounts of acetate and pyruvate. During nitrate reduction cell growth increased slightly and the formation of succinate and lactate decreased while acetate increased. The level of nitrate reductase activity in the extracts was several times higher in cells grown on nitrate, while the fumarate reductase level was lowered compared with cells not grown on nitrate. In extracts, nitrate reductase and fumarate reductase occurred mainly in a particulate fraction, whereas nitrite reductase was mostly in a soluble fraction. Addition of tungstate to the culture medium decreased the nitrate reductase activity as well as nitrite formation, suggesting that the enzyme is a molybdoprotein. Ferredoxin from Clostridia and viologen dyes served as electron donors for nitrate reduction. A c-type cytochrome with peaks at 557.5, 527, and 423nm in the extract was partly reduced by NADH and oxidized by fumarate, and to a lesser extent also by nitrate, even in extracts from cells grown in the presence of nitrate. Km′s for substrates and pH optima were also reported for the reductases in crude extracts.
Edited and published by : Applied Microbiology, Molecular and Cellular Biosciences Research Foundation/Center for Academic Publications Japan Produced and listed by : TERRAPUB, Center for Academic Publications Japan/Shobi Printing Co., Ltd. (-Vol.60,No12), Center for Academic Publications Japan/InternationalAcademic Printing Co., Ltd.(-Vol.54,No1)