No abstract

Cells of Micrococcus halodenitrificans have a high poly-β-hydroxybutyric acid (PHBA) content, the oxidation of which accounts for the high endogenous respiration of this organism. The amount of polymer in resting cells decreased with time, and viability could be correlated with the polymer content of the cells. PHBA-rich cells maintained their viability for longer periods than PHBA-poor cells. Cells oxidized PHBA in the presence of sodium chloride but not in water; optimal oxidation occurred in 0.33 to 0.75 M NaCl.The results suggest the following oxidation pathway. A diethyl p-nitrophenyl phosphate sensitive depolymerase catalyzes the hydrolysis of the polyester to β-hydroxybutyrate. This soluble substrate is oxidized by a DPN-linked D(−)-β-hydroxybutyric acid dehydrogenase to acetoacetate. Acetoacetate is further oxidized in the presence of oxalacetate, ATP, and coenzyme A. Citrate is formed, indicating the presence of the condensing enzyme, and PHBA oxidation is strongly inhibited by malonate. These findings suggest that oxidation proceeds via the tricarboxylic acid cycle.

No abstract

New methods of sterilization employing a chemical with moderate heat and ultrasonic energy have been devised. Inactivation of high-density bacterial spore suspensions is achieved by treatment with low concentration aqueous acid glutaraldehyde solutions at temperatures above or about 54 C. Low (20 kHz) or high (250 kHz) frequency ultrasonic energy is synergistic with glutaraldehyde. Rapid inactivation may also be achieved by using ultrasonic energy and aqueous alkalinized glutaraldehyde solutions at low (25 C) or moderate (55 C) temperatures. If compared to present room temperature techniques, "surface sterilization" time for contaminated objects can be reduced from hours to minutes.

Intact spores of Bacillus subtilis are susceptible to subtilopeptidase attack and this enzymatic reaction induces changes in the spore similar to those that take place during "physiological" germination. Germination occurred between pH 5.5 and 10.0 showing a pH optimum of 9.0 and between 25 °C and 45 °C with an optimum of 37–40°. Subtilopeptidase-induced germination took place in completely anaerobic conditions. Sublethal heating of spore suspensions increased the rate of subtilopeptidase-induced germination. Germination with subtilopeptidase was almost completely inhibited by an excess of diisopropyl fluorophosphate. L-Alanine-induced germination was not affected by diisopropyl fluorophosphate. Participation of the spore metabolism in subtilopeptidase-induced germination seemed likely. These results suggest that subtilopeptidases initiate spore germination by releasing germination agents from the spore.No significant loss of viability was noted until after exposure to the proteolytic enzyme for at least 60 minutes. Prolonged exposure of B. subtilis spores to subtilopeptidase results in death of the exposed spores.Subtilopeptidase-induced germination was also observed in several spores of other members of the genus Bacillus.