Twelve unfaunated male calves aged 5-8 months were inoculated with monogeneric protozoa (Epidinium ecaudatum, Eudiplodinium maggii or Entodinium. spp.) or mixed protozoa population. Thus, five groups of rumen protozoa population were established; Unf (unfaunated, protozoa- free), Epi (Epidinium ecaudatum mono-faunated), Eud (Eudiplodiniummaggii mono-faunated), Ent (Entodinium spp. mono-faunated), and Mix (mixed Ophryoscolecids protozoa faunated). The number of total viable bacteria in the rumen was significantly lower in the Epi, Eud and Mix groups than the Unf group. The population of amylolytic bacteria was significantly lower in the Epi group than the Unf group. That of pectinolytic bacteria was higher in the Ent group than the other faunated groups. The number of methanogenic bacteria was significantly higher in the Ent, Eud and Mix groups than Unf, however the Epi group had a lower value than the other faunated groups. The concentration of rumen ammonia-N peaked at 1h after feeding and was significantly higher in the Mix group than in the other groups, and was the lowest in the Unf group. The concentration of rumen volatile fatty acids (VFAs) increased until 2h after feeding. The values of the Unf group were lower than the other groups, but the differences were not significant. The molar proportion of acetate was lowest in the Mix group, highest in the Unf group and the other groups had values intermediate between these two groups. The proportion of butyrate and propionate was lowest in the Unf group.
The introduction of the acetoxymethyl ester of fura-2 (fura-2/AM) has made possible the measurement of the concentration of intracellular free calcium (free [Ca2+]i) in bacteria. We report here a study of intracellular calcium levels and exclusion mechanisms in Streptococcus bovis using fura-2/AM and 45CaCl2. The total [Ca2+] i in cells not energized with glucose increased in proportion to external Ca2+ concentration over the range 0.1-0.5mM, the intra- and extracellular levels being approximately equal. In contrast, the free [Ca2+]i remained at 71.1± 1.9nM in the face of extracellular concentrations from 0.1 to 5mM. Energizing by the addition of glucose produced a dramatic increase in the intracellular concentration of ATP and a marked decrease in total [Ca2+]i, but had no effect on the free [Ca2+]i regardless of whether extracellular calcium was high or low. Total [Ca2+]i was affected little, if at all, by the metabolic inhibitors FCCP and DCCD, implying that neither proton motive force nor F0F1H+-ATPase is necessary for calcium exclusion. In contrast, total [Ca2+]i and ATP were both greatly reduced by iodoacetate. These results suggest that 1) S. bovis has a remarkable calcium buffering capacity, and 2) most of its intracellular calcium exists in a bound form which can be released by energizing via a mechanism coupled to ATP hydrolysis.
Dextransucrase an enzyme from a new strain of Leuconostoc mesenteroides LM1 cells has been extracted by 10% sucrose acetate buffer solution and purified by ammonium sulphate fractionation. Immobilization of the enzyme on hydroxyapatite changed the temperature optima of the free(soluble) form of dextransucrase from 30 to 50°C. The hydroxyapatite-immobilized dextransucrase could be stored in a refrigerator for 6-8 months and showed activity in 4-5 cycles of repeated use. Similar results were obtained using calcium alginate beads immobilized dextransucrase system. Some of the chemicals which inhibited free dextransucrase had no effect on the immobilized enzyme on hydroxyapatite.
The interactions of the virulent form of the phase one variant 19061/1 of the bacterial insect pathogen Xenorhabdus nematophilus ATCC 19061/1 (refers to the phase one form) and four avirulent Tn5-insertion mutants with the antibacterial system of non-immune larvae of Galleria mellonella (the greater wax moth) were characterized. There was no discernible relationship between extracellular enzymes of the bacterial strains and bacterial virulence for the insects. Spheroplast formation was negatively correlated with virulence. Bacterial adhesion to the hemocytes varied with the hemocyte type and bacterial strain and was not related to virulence. Changes in the levels of outer membrane proteins with apparent molecular weights of 19 to 40kDa may be associated with bacterial adhesion to hemocytes but not to bacterial virulence. Bacterial hydrophobicity influenced the adhesion of the bacteria to the granulocytes but not to the plasmatocytes. The profiles of the removal of the bacteria from the hemolymph, in vivo, varied with the bacterial strain and was not correlated with virulence. Mutant bacteria possessed leaky outer membranes which released serine proteases that activated the prophenoloxidase system and may have facilitated bacterial adhesion to the hemocytes. Hemocytes were damaged by the lipopolysaccharides isolated from the bacterial strains. The rate of hemocyte damage, however, was less with the bacterial mutants and was due to the slower rates of release of lipopolysaccharides from these strains. The long-term survival of the bacteria in the insects varied with the bacterial strain. Although both the virulent and avirulent strains achieved the same final concentration, the avirulent isolates took longer to achieve the level. This delay may allow the insect to produce antibacterial proteins and/or detoxify virulence-factors (e.g. endotoxin) tipping the balance in favour of the host's survival.
A new species, Trichosporon domesticum Sugita, Nishikawa et Shinoda, is proposed for a strain isolated from the house of a summer-type hypersensitivity pneumonitis patient in Kumamoto, Japan. The nuclear DNA of T. domesticum showed intermediate relatedness to that of T. montevideense; however, their genome sizes were significantly different. These findings suggest that they represent separate species. T. domesticum is distinguished from T. montevideense by its inability to assimilate D-arabinose, ribitol, and dulcitol. The type strain of T. domesticum is strain M 9401, which has been deposited in the Japan Collection of Microorganisms as JCM 9580.
The colony-forming process of bacteria in a paddy field soil on 100-fold diluted nutrient broth (DNB) plates containing As(III) (250-1, 000ppm) was analyzed by the first-order reaction (FOR) model. The process on plates with 250ppm As(III) was simulated by a superimposition of three FOR model curves, which are respectively referred to as component colony-forming curve (cCFC) I, II, or III. Bacterial isolates from the 250 ppm As(III) plates were divided into three groups according to cCFC, along which each respective bacterium produced its colony. The three cCFC groups showed different trends of physiological properties: (1) the range of tr, which is the waiting time for the appearance of the first colony of each single population in the presence or absence of As(III), (2) the range of the maximal tolerant As(III) concentration for each isolate and some of its taxonomic properties. Twelve out of 72 strains examined harbored one or more plasmids, suggesting location of As(III)-tolerant genes on the chromosomal DNA.