Mutagenesis and enrichment of auxotrophs in Penicillium chrysogenum.

An efficient method for isolation of auxotrophs of Penicillium chyrysogenum involving mutagenesis with ethyl methanesulfonate followed by enrichment with sodium pentachlorophenate was developed. The auxotroph frequencies obtained were 30 to 40%.

Fermentation process for double-stranded ribonucleic acid, an interferon inducer.

Double-stranded ribonucleic acid (ds-RNA) isolated from Escherichia coli infected with bacteriophage MS2 is a potent interferon inducer. High levels of ds-RNA are formed in nonpermissive cells infected with MU9, an amber coat protein mutant of MS2. This mutant has been used to develop a process for large-scale ds-RNA production.

Production of an autoinhibitor by a thermophilic bacillus.

Premature cessation of rapid, exponential growth and a low final cell yield were observed with a thermophilic bacillus in a glucose-mineral salts-vitamin medium. Restricted growth was not due to nutrient or oxygen limitation, to depressed pH, or to the physical effects of "crowding." Glucose conversion to cellular material was efficient at a low glucose charge (0.

Porphyrin overproduction by Pseudomonas denitrificans: essentiality of betaine and stimulation by ethionine.

Ethionine supplementation of a defined medium for growth of Pseudomonas denitrificans inhibited vitamin B(12) overproduction and led to the elaboration of a red pigment. The pigment was shown to be coproporphyrin III. Inhibition by ethionine of cobalamin synthesis is probably due to interference of methylation of the corrin nucleus by methionine.

Microbial epoxidation of cis-propenylphosphonic to (-)-cis-1,2-epoxypropylphosphonic acid.

Eighteen species of Penicillium, one of Oidium and one of Paecilomyces were found to effect a stereospecific conversion of cis-propenylphosphonate to fosfomycin which was identified by paper chromatography and gas-liquid chromatography (GLC) of the trimethylsilyl esters. Penicillium spinulosum carried out the epoxidation only after the glucose substrate had been utilized. Glucose controlled the epoxidation since its residual concentrations in the broth severely depresses the reaction.

Product inhibition of the fermentative formation of glutamic acid.

The addition of penicillin to cells of Corynebacterium glutamicum growing in 5-liter fermentors initiated the excretion of glutamic acid. The rate of glutamate production in fermentors declined continuously with time and reached 75% of the initial rate in 24 hr after penicillin had been added. The addition of glutamate to resting cell suspensions had only a slight effect on sugar utilization but caused a marked decrease in glutamate excretion.

Reversal by citrate of the iodoacetate and fluoride inhibition of glutamic acid production by Corynebacterium glutamicum.

Citrate reversal of iodoacetate inhibition of glutamate synthesis is nonmetabolic. Reversal of fluoride inhibition is metabolic, occurring only at low Mg concentrations.

Alternate requirement for vitamin B12 or methionine in mutants of Pseudomonas denitrificans, a vitamin B12-producing bacterium.

Experiments are described which indicate that Pseudomonas denitrificans, an organism that overproduces vitamin B(12), uses the B(12) pathway exclusively for methionine synthesis.

Glucose-6-phosphate dehydrogenase and its deficiency in mutants of Corynebacterium glutamicum.

Corynebacterium glutamicum is a member of a group of taxonomically related glutamate-excreting bacteria which utilize glucose both by the Embden-Meyerhof and the pentose phosphate pathways, the latter sequence accounting for 10 to 38% of the glucose metabolized. Some of the properties of glucose-6-phosphate dehydrogenase in crude extracts of C. glutamicum were studied.

Dependence of diaminopurine utilization on the mutational site of purine auxotrophy in Bacillus subtilis. II. Tracer experiments.

Tracer experiments were carried out in an attempt to explain why guanineless auxotrophs can use diaminopurine as a guanine replacement but nonexacting purine auxotrophs cannot do so. Cell suspensions of the nonexacting purineless Bacillus subtilis MB-1356 incorporated more radioactivity from diaminopurine-2-(14)C into nucleic acid than did guanineless B. subtilis MB-1517.

Dependence of diaminopurine utilization on the mutational site of purine auxotrophy in Bacillus subtilis. 1. Nutritional experiments.

An attempt was made to explain the puzzling observation that in bacteria 2,6-diaminopurine can replace guanine for guanineless mutants and for xanthineless mutants (both of which can make adenosine monophosphate de novo) but not for nonexacting purine auxotrophs (which cannot make adenosine monophosphate de novo). The analogue failed to inhibit the growth of nonexacting purineless Bacillus subtilis MB-1356 growing on guanine. In fact, growth was somewhat stimulated.

Thiamine-dependent accumulation of tetramethylpyrazine accompanying a mutation in the isoleucine-valine pathway.

A mutant of Corynebacterium glutamicum was found to accumulate high concentrations of a material which crystallized upon cooling of the broth. The compound was identified as tetramethylpyrazine. The mutant was found to require isoleucine, valine, leucine, and pantothenate for growth.

Phosphohydrolases of a Bacillus subtilis mutant accumulating inosine and hypoxanthine.

Although adenine-requiring auxotrophs of Bacillus subtilis accumulate large quantities of inosine or hypoxanthine, or of both, they do not accumulate inosine-5'-monophosphate (IMP). Experiments directed at understanding this phenomenon were conducted with an adenineless auxotroph and with a mutant derived from it which lacked alkaline phosphohydrolase. It was found that B.