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EFFECT OF OXYGEN ON GLUCOSE DISSIMILATION BY HETEROLACTIC BACTERIA

1970; Microbiology Research Foundation; Volume: 16; Issue: 6 Linguagem: Inglês

10.2323/jgam.16.6_543

1349-8037

Shigetaka Yashima, Keiichi Kawai, Yoshirō Okami, Yuji Sasaki,

Diet, Metabolism, and Disease

It has been reported by several investigators that most strains of heterolactic bacteria are capable of utilizing oxygen and produce lactate, acetate, and carbon dioxide, as major products from glucose under aerobic conditions (1-5).This paper describes the remarkable effect of oxygen on glucose dissimilation in resting cells of heterolactic bacteria.All the organisms used in this study were grown under stationary conditions at 30° in a medium containing (in per cent), glucose, 2.0; anhydrous sodium acetate, 2.0; peptone, 1.0; meat extract, 1.0; NaCI, 0.5; yeast extract, 0.2; and MnSO4.7H2O,0.05 (pH 7.0).The cells were harvested late in logarithmic growth phase and washed three times with cold distilled water.Aerobic dissimilation of glucose was carried out in 100-m1 Erlenmeyer flasks on a reciprocating shaker operating at 145 strokes (2 cm) per min, and stationary (semi-anaerobic) dissimilation of glucose was carried out in 15-m1 test tubes.Each flask or tube contained the following substances : 500 imoles of glucose, 5 cimoles of MgSO4, 5 ml of 0.1 M phosphate buffer (pH 7.0), and 40-50 mg (dry weight) of washed cells.All incubations were carried out at 30°.Samples were taken during incubation, cooled rapidly by immersing the test tube or flask in ice, and centrifuged.The supernatant fluids thus obtained were analyzed by spectrophotometry for glucose (6), lactate (7), acetate (8), and ethanol (9) according to the indicated procedures.The results obtained after 90 min of incubation are summarized in Fig. 1.From these results, it is worth noting that the resting cells of Lactobacillus brevis and L. buchneri lose their fermentative activities under stationary conditions, while they can dissimilate glucose under aerobic conditions.These phenomena were also confirmed after 120 or 150 min of incubation.