No abstract

The effect of oxygen supply on L-leucine fermentation was investigated employing a leucine-producing mutant of Brevibacterium lactofermentum. Since it was not possible to measure oxygen tension below 0.01 atm by a Teflon-coated oxygen electrode, the degree of satisfaction of the cells' oxygen demand (cells' respiration rate/maximum oxygen demand of cells, rab/KrM) and the redox potential of the culture medium (E, mV) were used as indices to oxygen supply in cultures under low oxygen tension. When the oxygen demand of the cells was satisfied (rab/KrM = 1.0) and the E value was between --90 and --110mV, L-leucine formation was 26.5 mg/ml. When the oxygen demand of the cells was not satisfied (rab/KrM = 0.85) and the E value was between --200 and --220 mV, L-leucine accumulation was 29.7 mg/ml. When the oxygen supply was extremely limited (rab/KrM = 0.27) and the E value was --280 mV, L-leucine formation was 12.9 mg/ml. A new method which simultaneously measures the redox potential and dissolved oxygen was applied to the determination of the critical dissolved oxygen level for cell respiration (PL crit), whick was too small to be detected by conventional oxygen electrodes. The value of PL crit of the leucine producer was estimated as 0.0002 atm.

Penicillin-resistant mutants were derived from Corynebacterium hydrocarboclastus R-7. One of them produced 84g/liter of L-glutamic acid from hydrocarbon, though its parent strain •õ This paper was presented at the 19th Symposium on Amino Acid and Nucleic Acid held on 1st Decem ber,

It is well known that a good many microorganisms can utilize hydrocarbons as a sole carbon source. We have as yt little information, however, as to what kinds of intermediate or end products are produced by the microbial dissimilation of hydrocarbons. Above all, the formation of amino acids from hydrocarbons has not been reported. We have isolated many strains of microorganisms from soil samples by selective culture techniques in a medium containing kerosene and mineral salts, in order to examine if the products of economical value such as amino acids, organic acids, fatty acids, steroids, nucleic acids and their related compounds, can be produced by those microorganisms. Shaking cultures of those microorganisms were carried out in the medium containing 3.5% kerosene, 3.5% liquid paraffin and mineral strains out of 127 strains tested produced amino acids in their broths, after 4 days cultivation