Evaluation of 36 Minitek tests and a new approach for identification of nonfermenters

Thirty-six Minitek (BBL Microbiology Systems, Cockeysville, Md.) tests were evaluated with 625 Kansai Medical University stock strains of 22 species and one group of nonfermentative gram-negative rods able to grow on ordinary peptone media. Among the 36 tests, 15 were selected because a clear-cut reaction was shown by all 625 Kansai Medical University strains. Of these 15 tests, 12 were further selected for routine use because they were regarded as useful for the identification of nonfermenters. The 12 tests were arranged into the following four groups: (i) lysine-arginine-ornithine, (ii) urea-ortho-nitrophenyl-beta-D-galactopyranoside-dextrose aerobic, (iii) maltose-xylose-starch, and (iv) esculin-nitrate reduction-indole. A new profile system for four digits, the Minitek Y-Y (Yabuuchi and Yamanaka) system, consisting of 64 numbers which represent each single species and 11 numbers which give two to four species, is herein proposed. The system was designed primarily for a less expensive identification of gram-negative rods already confirmed in a butt of either triple sugar iron or Kligler iron agar for their lack of ability to ferment dextrose. Among the 539 clinical isolates obtained from 3 hospitals, 511 strains identifiable by classical methods were also identified by the Minitek Y-Y system.

Antagonistic effects of Bacillus natto and Streptococcus faecalis on growth of Candida albicans

The growth-inhibitory effects of Bacillus natto and Streptococcus faecalis on Canida albicans were investigated. When inoculated into the filtrate of a long-term culture of B. natto strain BN (BN), a stock culture of C. albicans RIMD 0301020 lost its viability completely, whereas C. albicans RIMD 0301011, a fresh isolate from a clinical source, did not. In continuous flow (CF) culture the growth of both strains of C. albicans was suppressed by mixed cultivation with BN. On the other hand, in classical batch culture BN did not suppress the growth of C. albicans. S. faecalis BIO-4R, a multi-drug resistant strain, was also antagonistic to C. albicans RIMD 0301011 but symbiotic with BN in CF culture. These findings suggest that BN in concert with S. faecalis BIO-4R may inhibit the growth of C. albicans in the intestinal tract.

Selective inhibition of Klebsiella aerogenes growth on pentoses by pentitols

Selective inhibition of growth by pentitols was observed when Klebsiella aerogenes M-7 which could not utilize pentitols was grown on pentoses. D-Arabitol inhibited the growth on D-arabinose as a sole carbon source, but had no effect on the growth on L-arabinose, D-xylose, and D-ribose. Similarly, L-arabitol inhibited the growth on D-arabinose and L-arabinose, ribitol inhibited the growth on D-arabinose and L-arabinose, and xylitol inhibited the growth on D-xylose. From the following reasons, we postulated that the selective growth inhibition by pentitols was due to the competitive inhibition of pentose isomerase reaction by the cell by pentitols. (i) D-Arabinose transport activity was not inhibited by pentitols. (ii) Induction of D-arabinose and L-arabinose isomerases was not inhibited by D- and L-arabitol, respectively. (iii) The specificity of growth inhibition by pentitols was the same as that of competitive inhibition of pentose isomerases by pentitols.

Pentose metabolism in Mycobacterium smegmatis: comparison of L-arabinose isomerases induced by L-arabinose and D-galactose

D-Galactose, which did not serve as a growth substrate, was found to induce an L-arabinose isomerase of similar properties to the L-arabinose-induced L-arabinose isomerase. In both cases the pH profiles, pH stability, optimum temperature, heat stability, substrate specificity, metal ion requirements, mobility on polyacrylamide gel electrophoresis, and kinetic properties of the induced isomerases were identical. It appears possible that D-galactose was incorporated into the cells by an L-arabinose permease system that was alos induced by D-galactose.

Effect of enterohepatic circulation on bile production in regenerating liver

In an investigation of the role of portal blood flow in bile production and of changes in the enterohepatic circulation of bile in the regenerating liver, various branches of the portal vein were ligated in dogs, bile was collected from the liver lobes supplied by ligated and by nonligated portal branches, and the composition of the bile was analyzed. 1. Bile flow and bilirubin excretion from the ligated, atrophic liver lobes decreased with a disappearance of glycine-conjugated bile acids, but bilirubin excretion and especially bile flow increased greatly without any changes in bile acids composition in the nonligated, regenerating liver lobes as the portal blood flow to them per liver weight increased. 2. Infusion of gallbladder bile into the terminal ileum stimulated bile secretion in the nonligated lobes in the postoperative period, but not in the ligated lobes except immediately after the ligation of the portal vein branches supplying two-thirds of the liver. These findings indicate that bile secretion by the ligated lobes could be stimulated via the hepatic artery and the nonligated lobes might be via both the portal vein and the hepatic artery after the infusion during early postoperative period.

Pentose metabolism in Mycobacterium smegmatis: specificity of induction of pentose isomerases

The induction of D-xylose, D-ribose, L-arabinose, and D-lyxose isomerases by various sugars was studied to determine the configuration necessary for induction. D-Xylose isomerase was only induced by D-xylose, whereas D-ribose isomerase was induced by D-ribose, L-rhamnose, and L-lyxose. L-arabinose isomerase was induced by L-arabinose, D-galactose, L-arabitol, D-fucose, and dulcitol, whereas D-lyxose isomerase was induced by D-lyxose, D-mannose, D-ribose, dulcitol, and myoinositol. Some compounds such as dulcitol, D-galactose, and D- or L-fucose which do not support growth are still able to serve as inducers for various pentose isomerases.

[Cellular responses to vibration during dental drilling with belt drive motor engine (in vitro) (author's transl)]

There have been many reports on the pulpal reaction caused by vibration during high speed dental drilling with air turbine hand-piece. It is, however, not clear pulpal responses to vibration of low speed drilling with 7 000 rpm of belt drive motor engine which produces a fundamental vibration of about 170 cps having most unpleasant sensation at vestibular apparatus. Here, cellular responses of L strain cells to vibration derived from 7 000 rpm and 15 000 rpm of belt drive motor engine were observed in vitro system. There is no difference between the both cellular responses to the vibration of 7 000 rpm and 15 000 rpm. Suspended free cells were easily influenced and degenerated by the vibration, and remarkably checked in their cell-multiplication. On the contrary, in the cells adhered to the substratum of glassware, no degeneration and no inhibitory effect were observed. And the cells showed reversible response of cytoplasmic shrinkage only.

Production of polyol dehydrogenases in bacteria

D-Arabitol dehydrogenase (D-arabitol [Formula: see text]D-xylulose, D-arabitol:NAD oxidoreductase, EC 1.1.1.11) was found in the D-sorbitol-grown or D-mannitol-grown cells of Agrobacterium tumefaciens, Pseudomonas fluorescens, Pseudomonas aeruginosa, Pseudomonas coronafaciens, Sarcina aurantiaca, and Sarcina marginata. This enzyme was accompanied by D-sorbitol dehydrogenase. Activity of D-mannitol dehydrogenase (D-mannitol:NAD oxidoreductase, EC 1.1.1) was also found in Pseudomonas fluorescens, Pseudomonas coronafaciens, Pseudomonas aeruginosa, Sarcina marginata, and Sarcina aurantiaca. D-Mannitol dehydrogenase was produced from Lactobacillus brevis, L. pentoaceticus, L. gayonii, and Leuconostoc mesenteroides in fructose media. D-Fructose seemed to be essential for the enzyme production by L. brevis, but Leuconostoc mesenteroides produced an equal amount of the enzyme from D-glucose, D-fructose, or sucrose media. Mannitol was found to be effective for enzyme production in a shake culture of Leuconostoc mesenteroides and of L. brevis.