- Volume 97, Issue 1, 1976

SUMMARY: The principal products of endogenous metabolism of the obligate anaerobe Peptococcus prévotii were carbon dioxide, ammonia, acetate and butyrate, which are also produced by fermentation of nucleosides, purines and ribose, thus supporting our previous finding that RNA is the only cellular component to undergo substantial degradation under starvation conditions. Minor products were hydrogen, formate and propionate. The stoicheiometries of fermentation of xanthine, adenine, adenosine and ribose were determined. The ability to ferment exogenous nucleosides, purines and ribose declined rapidly on starvation, as did the ability to generate ATP from xanthine, and was paralleled by the loss of viability. However, addition of pulses of xanthine or adenine to organisms in the early stages of starvation sustained their adenylate energy charge and prolonged their viability. Evidence suggests that P. prévotii dies when its principal energy source (RNA) is depleted, and a possible explanation is that the transport function of the cytoplasmic membrane decays rapidly under these conditions so that, on transfer to a recovery medium, uptake of nutrients is inadequate to support growth.

SUMMARY: An examination of the soluble carbohydrates of the wheat stem rust fungus, Puccinia graminis Pers. f. sp. tritici Erikss. & E. Henn., showed the presence of glucitol (sorbitol), ribitol, fructose, and traces of xylitol, as well as confirming the presence of mannitol, arabitol, trehalose, inositol and erythritol. Ribitol and glucitol were major components in glucose-grown mycelium, and appeared to be the major components in mycelium parasitic on wheat leaves, but not in germinated or ungerminated uredospores. It is suggested that glucitol and ribitol may be intermediates (or by-products) of glucose utilization, whereas mannitol, arabitol and trehalose represent storage carbohydrates.

SUMMARY: The growth responses of an acetate-utilizing isolate of Butyrivibrio fibrisolvens to CO2, acetate and pyruvate were determined using a chemically-defined medium. Carbon dioxide was essential for growth and both acetate and pyruvate increased growth. 14C from [1-14C]acetate was found mainly in butyrate while 14C from 14CO2 or [1-14C]pyruvate appeared predominantly in formate and lactate. These results, together with those obtained with enzyme preparations, indicated pyruvate synthase, pyruvate-CO2 exchange and pyruvate formate lyase to be active.

SUMMARY: The bacterial drug-resistance plasmids Sa, R388 and R7K that comprise the W compatibility group were transferred by conjugation to species in the genera Escherichia, Salmonella, Shigella and Pseudomonas, chosen for their lack of common pili. On receiving the W plasmids, all strains produced pili, which were similar morphologically, at average frequencies of up to 3·0 pili/cell. The pili determined by the W plasmids were also related serologically, but unrelated to those of other plasmids. R− segregant strains which had lost their plasmids showed a simultaneous loss of both pili and drug-resistance characteristics.

W-pili are pointed flexible filaments 10 to 12 nm thick, with an average length of 450 nm. The best host found was Salmonella typhimurium.

SUMMARY: Pigmentation mutants of Pseudomonas phenazinium unable to synthesize iodinin, or producing it only in reduced amounts, were isolated. The abilities of the mutants to synthesize nine other phenazines were also altered. Cross-feeding experiments and the altered patterns of pigment production suggested metabolic relationships between the phenazine pigments, and a scheme for their biosynthesis is proposed.

SUMMARY: The aspartase (l-aspartate ammonia-lyase, EC. 4.3.1.1) structural gene, aspA, was mapped by two-factor and three-factor transductional crosses using phage P1. Cotransduction frequencies between aspA and other markers were: ampA (69%); frdA (48 to 67%); mel (35%); purA (17%); fdp (1·6%). The sequence of markers within the corresponding segment (91 to 95 min) of the Escherichia coli linkage map was shown to be mel-aspA-ampA-frdA-purA-fdp.

SUMMARY: Cysts of Polytomella parva and Polytomella caeca were recovered after 7 days storage at cryogenic temperatures following drying on shredded filter paper, silica gel or without added substrate. Accelerated storage testing, by exposing dried material to elevated temperatures, indicated that shredded filter paper was the best of the substrates tested. Polytomella parva was recovered after 5 years storage at − 30 °C when dried on filter paper but not when dried on silic agel. Determinations of the number of cysts recovered indicated that viable cysts survived all conditions of storage tested. However, excystment following storage was delayed, the extent depending on storage conditions and the substrate used for drying. Most rapid recovery occurred when cysts were rehydrated immediately after drying, and after storage on filter paper at below − 70 °C.