Presence Of Bacterial Cells Research Articles

Some factors inhibiting amplification of the Staphylococcus aureus enterotoxin C 1 gene ( sec+) by PCR

PCR amplification of the sec + gene for staphylococcal enterotoxin C 1 (SEC 1) can be achieved from as little as 10 fg total genomic DNA (equivalent to less than 10 cells) using two nested primer pairs. The presence of bacterial cells, particularly thermonuclease-producing staphylcocci, and the thermonuclease enzyme (TNase) itself, were found to be factors which individually and together reduced the sensitivity of PCR amplification.

Antifungal, Synergistic Interaction Between Chitinolytic Enzymes fromTrichoderma harzianumandEnterobacter cloacae

Biocontrol strains from the genera Enterobacter and Pseudomonas and two chitinolytic enzymes from Trichoderma harzianum isolate P1 were combined and tested for antifungal activity in bioassays. Inhibitory effects on spore germination and germ tube elongation of Botrytis cinerea, Fusarium solani, and Uncinula necator were synergistically increased by mixing fungal enzymes and cells of Enterobacter cloacae but not of Pseudomonas spp. Culture filtrate of E. cloacae contained antifungal compounds and produced moderate levels of inhibition, either in plate assays or in bioassays conducted in potato-dextrose broth. However, the combination of bacterial culture filtrate with fungal chitinolytic enzymes generated only an additive response, indicating that the presence of bacterial cells was required for a synergistic effect. Chitinolytic enzyme activity in the presence of chitinous substrates enhanced the growth of E. cloacae and readily restored the ability of bacterial cells to bind to hyphae of the pathogens despite high concentrations of D-glucose or sucrose in the medium. The results of this study suggest that transgenic bacteria, capable of binding to fungal cell walls and expressing fungal genes encoding cell wall-degrading enzymes, may be powerful biocontrol agents

Uptake of Azotobacters by Somatic Fusion of Cell-wall Mutants of Chlamydomonas reinhardii

Summary Nitrogen-fixing Azotobacters were mixed with algal cells before fusion of cell-wall mutants of eukaryotic green alga, Chlamydomonas reinhardii . Somatic fusion was performed by adding PEG solution into the mixture of two complementing arginine-requiring wall-less strains of alga. The alga cells first aggregated and then fused in presence of bacterial cells and the fusion products were obtained on selective medium. The bacterial cells have been found to be taken up by algal cells during fusion as shown in electron microscopic figures that they were present inside the algal cells after lysozyme treatment. The hybrids were maintained on nitrogen and carbohydrate free medium and we always found bacterial cells inside the algal cells and in the intercellular space of algal cells ten months after somatic fusion.

Effect of Bentonite Clay on the Growth of Gaeumannomyces graminis var. tritici and on its Interactions with Antagonistic Bacteria

The effects were studied of increasing concentrations of bentonite clay on the interactions between the fungal pathogen Gaeumannomyces graminis var. tritici and two bacterial antagonists. Clay increased the growth rate of G. graminis; this increase was statistically significant, though small, and could have been due to an effect on water availability. The effectiveness of one of the bacterial culture nitrates in restricting the fungal growth was reduced by the clay, though antagonism was maintained in the presence of bacterial cells. The clay may adsorb some of the bacterial toxins, and lowered water availability may increase bacterial antagonism before it significantly reduces fungal growth. Antagonism by the other bacterium was not affected by clay.

The effect of metabolic activation with rat liver preparations on the mutagenicity of several N-nitrosamines on a streptomycin-dependent strain of Escherichia coli

Summary The mutagenicity of dimethyl, diethyl, di- n -propyl, di- n -butyl, methyl- n -butyl, morpholine, piperidine, methylphenyl, ethyl- t -butyl and diphenyl nitrosamines was investigated using a mammalian metabolic activation system. Reverse mutation from streptomycin dependence to non-dependence in strain Sd-B(TC) of Escheyichia coli was used as the marker for mutagenicity. With this assay system the mutagenicity of metabolic breakdown products was determined by incubating the compounds with a rat liver preparation in the presence of bacterial cells. Reverse mutation was induced by all carcinogenic compounds tested, except methylphenylnitrosamine, whereas two non-carcinogenic compounds, ethyl- t -butyl nitrosamine and diphenyl nitrosamine did not give a significant increase in the rever sion frequency. The frequency of mutants induced by the compounds was decreased markedly by preincubation of the compounds with the liver preparation and the cofactor system prior to the addition of bacterial cells.

Biosynthesis of vitamin B12 by Propionibacterium shermanii V. Interrelationship between vitamin B12 and porphyrin synthesis

AbstractIron and cobalt inhibited the porphyrin synthesis in presence and absence of δ‐amino‐laevulinic acid (ALA). ALA greatly stimulated the porphyrin synthesis and inhibited the vitamin B12 synthesis. Addition of ALA removed the inhibitory effect of chloramphenicol and azaguanine on porphyrin synthesis. Azaxanthine decreased the porphyrin synthesis in the bacterial cells in presence of ALA. Sodium azide and 2,4‐dinitrophenol inhibited growth and vitamin B12 but had no effect on porphyrin synthesis. Malonate had no effect. It is deduced that ALA is the structural material suitable for porphyrin synthesis.

Biosynthesis of vitamin B 12 by Propionibacterium shermanii. V. Interrelationship between vitamin B 12 and porphyrin synthesis.

Iron and cobalt inhibited the porphyrin synthesis in presence and absence of δ-amino-laevulinic acid (ALA). ALA greatly stimulated the porphyrin synthesis and inhibited the vitamin B12 synthesis. Addition of ALA removed the inhibitory effect of chloramphenicol and azaguanine on porphyrin synthesis. Azaxanthine decreased the porphyrin synthesis in the bacterial cells in presence of ALA. Sodium azide and 2,4-dinitrophenol inhibited growth and vitamin B12 but had no effect on porphyrin synthesis. Malonate had no effect. It is deduced that ALA is the structural material suitable for porphyrin synthesis.

Reactivation of Ultra-Violet-Inactivated Bacteriophage by Visible Light

COLI-BACTERIOPHAGE of the 'T' group1 are inactivated at a logarithmic rate by ultra-violet light. Some of these phages can be reactivated inside bacteria that adsorb more than one inactive phage particle2. I recently observed another type of reactivation of ultra-violet irradiated phage, namely, reactivation upon exposure to visible light in the presence of bacterial cells (photo-reactivation). Since this phenomenon may cause serious misinterpretations of results obtained in working with irradiated phage, it may be useful to report it at this early stage of its investigation.