Howard I. Adler

PROTEIN SYNTHESIS AND VIABILITY IN X-IRRADIATED RHODOPSEUDOMONAS SPHEROIDES

Abstract In the photosynthetic bacterium Rhodopseudomonas spheroides the capacity for induced catalase synthesis is inhibited by low doses of X-rays to the same extent as the ability to form colonies. The inhibition is manifested fully within a few minutes after irradiation. The presence of catalase during and after irradiation does not modify the effect of X-rays on survival, and the activity of intracellular catalase is not altered by X-ray doses up to 100 kR. The effects of X-rays on catalase synthesis and survival are potentiated to the same extent by oxygen. Experiments dealing with kinetics and external factors suggest that X-rays act in an all-or-none manner, early in a sequence of events that culminates in synthesis of the enzyme. The syntheses of “general cell protein”, of proteins associated with bacteriochlorophyll in the chromatophores, and of constitutive catalase are inhibited by X-irradiation to about the same extent as the synthesis of inducible catalase and the ability to form colonies. The lethal action of X-rays is discussed in terms of the destruction of genetic material that directs the synthesis of proteins.

Isolation of anaerobes using an oxygen reducing membrane fraction: experiments with acetone butanol producing organisms

Abstract A sterile, oxygen consuming membrane fraction derived from Escherichia coli makes possible the development of new techniques for the isolation of oxygen sensitive bacteria. The membrane fraction removes oxygen rapidly and completely from a variety of bacteriological media. The membrane fraction is active over a broad pH (4–9.5) and temperature (5–65°C) range. It is not toxic to bacteria and cultures of anaerobic bacteria can be initiated from very small inocula in media made anaerobic by the use of the membrane fraction. The utility of isolation techniques using the membrane fraction was illustrated by examining 64 soil samples for the presence of acetone butanol producing anaerobes. These organisms were found in 84% of the samples. Forty-nine strains were ultimately isolated. They all produced acetone and butanol in quantities similar to that produced by a reference laboratory strain. We conclude that techniques for the isolation of anaerobes based on the use of the oxygen consuming membrane fraction are simple, efficient and likely to be applicable to other organisms from a variety of anaerobic environments.