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B D Jarvis

Publications and source records attributed to B D Jarvis.

31 records · Page 2Linked to original sources
PubMed1985

Isolation and characterization of transposon Tn5-induced symbiotic mutants of Rhizobium loti.

Rhizobium loti NZP2037 and NZP2213, each cured of its single large indigenous plasmid, formed effective nodules on Lotus spp., suggesting that the symbiotic genes are carried on the chromosome of these strains. By using pSUP1011 as a vector for introducing transposon Tn5 into R. loti NZP2037, symbiotic mutants blocked in hair curling (Hac), nodule initiation (Noi), bacterial release (Bar), and nitrogen fixation (Nif/Cof) on Lotus pedunculatus were isolated. Cosmids complementing the Hac, Noi, and Bar mutants were isolated from a pLAFR1 gene library of NZP2037 DNA by in planta complementation and found to contain EcoRI fragments of identical sizes to those into which Tn5 had inserted in the mutants. The cosmids that complemented the mutants of these phenotypic classes did not share common fragments, nor did cosmids that complemented four mutants within the Noi class, suggesting that these symbiotically important regions are not tightly linked on the R. loti chromosome.

DNA Transposable Elements↗
PubMed1981

Deoxyribonucleic Acid homology among lactic streptococci.

A comparison was made by deoxyribonucleic acid homology of 45 strains of lactic streptococci, using two strains of Streptococcus cremoris and three strains of Streptococcus lactis as reference strains. All S. cremoris strains were grouped together by deoxyribonucleic acid homology. S. lactis strains formed a second group, except that three strains of S. lactis showed a high degree of homology with S. cremoris strains. The three Streptococcus diacetylactis strains could not be differentiated from S. lactis strains. In spite of these differences between S. lactis and S. cremoris strains, the majority of S. cremoris, S. lactis, and S. diacetylactis strains studied had at least 50% of their base sequences in common. In contrast, Streptococcus thermophilus strains generally showed little relationship with the other strains of lactic streptococci. The relevance of these findings to the selection of starter strains for cheese making is discussed.

Journal Article↗
PubMed1978

The role of carbonate in the metabolism of glucose by Butyrivibrio fibrisolvens.

The amount of Na2CO3 added to semi-synthetic medium determined the length of the lag phase, the growth rate and the dry weight of three strains of Butyrivibrio fibrisolvens (WV1, NOR37, B835). With increasing CO3(2-) concentration the molar growth yield of bacteria, from glucosewas increased and, of the fermentation products, formate increased more than the other acids. CO3(2-)-limited cultures of strain WV1 (Group 2 Butyrivibrio) and strain NOR37 (Troup 1 Butyrivibrio) incorporated 14CO3(2-) into lactate and formate. In NOR37, lactate and formate had equal specific activities; in WV1, the formate specific activity was twice that of lactate. Strain WV1 had an active pyruvate synthase and an energy-dependent exchange between CO3(2-) and formate was demonstrated. In strain WV1 butyrate was produced mainly from glucose.

Carbonates↗
PubMed1974

Proteinase activity in slow lactic acid-producing variants of Streptococcus lactis.

Variants of Streptococcus lactis that produce lactic acid slowly in milk were isolated by inducing plasmid loss in the wild type at 39 to 40 C. Such strains had lost most of their surface-bound proteinase activity and were designated prt(-). The specific proteinase activities of S. lactis C10 prt(+) whole cells and solubilized cell walls were 7 and 18 times, respectively, those of the prt(-) strain, but spheroplast lysates of prt(+) and prt(-) strains contained similar proteinase activity. S. lactis H1 showed a similar relative distribution of activity between prt(+) and prt(-) cellular fractions, although the overall level was lower. The limited growth in milk, characteristic of prt(-) strains, can be explained in terms of their low surface-bound proteinase activity.

Animals↗
PubMed1974

Localization of proteinase(s) near the cell surface of Streptococcus lactis.

Two criteria suggest that most of the proteinase of Streptococcus lactis is localized in the cell wall. (i) Intact cells possess proteinase activity when incubated with a high-molecular-weight substrate. (ii) Most of the cell-bound proteinase activity is released during spheroplast formation under conditions which result in the release of only 1% of the intracellular enzymes aldolase and glyceraldehyde-3-phosphate dehydrogenase. The solubilized cell wall, plasma membrane, and cytoplasm fractions contained 84, 0, and 16%, respectively, of the total proteinase activity with casein as substrate. The physiological role of a surface-bound proteinase in this organism is discussed.

Caseins↗
PubMed1968

Lysis of viable rumen bacteria in bovine rumen fluid.

Streptococcus bovis and Butyrivibrio sp. were labeled with thymidine-methyl-(3)H, washed, and resuspended in rumen fluid or rumen fluid fractions obtained from Holstein and Jersey cows fed alfalfa hay once daily. Factors affecting the lytic activity found in untreated rumen fluid were examined. Day to day variation and differences before and after feeding were observed for the same cow. There were also differences between cows on the same day. For a given rumen fluid, the rate of release of label was roughly proportional to the number of labeled cells present over a 100-fold range in concentration. Removal of protozoa largely abolished the lytic action of fresh rumen fluid for S. bovis, but some soluble lytic activity remained. Mixed rumen protozoa added to media containing labeled S. bovis caused label to appear in solution. In a sample of rumen fluid containing 4.3 x 10(4) protozoa/ml 5.2% of the S. bovis population were destroyed by protozoa per hr. The mean rate of destruction for 12 runs on whole rumen fluid was 8.7% per hr with a standard deviation of 6.05. Parallel experiments with Butyrivibrio indicated that soluble lytic factors were more important for this organism. They could be destroyed by autoclaving and were generated when viable rumen bacteria were resuspended in autoclaved rumen fluid. The lysis of S. bovis and Butyrivibrio, at equal cell densities, by mixed rumen protozoa was compared in 30% rumen fluid media, and Butyrivibrio appeared to be more readily lysed than S. bovis.

Animals↗
PubMed1968

Factors influencing agnotobiotic cultures of the rumen ciliate, Entodinium simplex.

The nutrition of Entodinium simplex was studied, with foliage of bluegrass (Poa pratense), perennial ryegrass (Lolium perenne), and grains of wheat (Triticum vulgare) as substrates in agnotobiotic cultures. Entodinium grew poorly when the substrates were autoclaved; better growth was obtained when the substrates were sterilized with ethylene oxide vapor. The concentration of ethylene oxide and the amount of moisture influenced the sterility and nutritional adequacy of the treated substrate. Autolysates and hydrolysates of mixed rumen protozoa stimulated growth. Protozoal extracts did not replace factors destroyed by autoclaving. Clarified rumen fluid assisted the cultivation of entodinia from small inocula but was detrimental to established cultures. Success of cultures was influenced by the medium used to grow the inoculum as well as by the medium inoculated. The results indicated that the composition of the bacterial population influences the growth of E. simplex.

Animals↗
PubMedDate not supplied

Isolation and characterization of a Rhizobium loti gene required for effective nodulation of Lotus pedunculatus.

A Rhizobium loti gene required for effective invasion of the host Lotus pedunculatus has been identified by transposon Tn5 mutagenesis. Cosmids that complemented a previously isolated mutation (239) at this invasion (inv) locus were identified by in planta complementation and used to construct a physical map of the gene region. The insertion site of Tn5 in PN239 was mapped to a 7.5-kb EcoRI fragment, which complemented the mutation when subcloned into pLAFR1. Further Tn5 mutagenesis of the 7.5-kb fragment was carried out in Escherichia coli using bacteriophage lambda 467, and the mutations homogenotized into R. loti NZP2037. Three additional Fix- mutations were isolated, and these were found to map adjacent to the position of the original mutation in strain PN239. All the other Tn5 insertions isolated in the 7.5-kb fragment gave a Fix+ phenotype on L. pedunculatus. Electron microscopic examination of the L. pedunculatus nodules induced by the isolated Fix- mutants showed that bacteria were either blocked in release from the infection threads or were unable to undergo normal bacteroid development. The inv locus as defined by the Tn5 insertions was sequenced, and a single open-reading frame (ORF) of 576 bp, corresponding to a polypeptide of 21.3 kDa, was identified. The position and orientation of this ORF were consistent with those of the isolated Tn5 Fix- insertions.

Amino Acid Sequence↗