- Volume 68, Issue 1, 1971

SUMMARY: Carbohydrate fermentation by the flagellate protozoan Trichomonas foetus results in the production of large amounts of hydrogen by an unknown mechanism. Impermeability of T. foetus to pyruvate at neutral pH may explain earlier failures of other workers to demonstrate unequivocally the intermediate participation of pyruvate in this fermentation. Intact cells of T. foetus have now been shown to ferment pyruvate at pH 4·0. In addition pyruvate is metabolized rapidly at pH 6·0 by cell-free extracts although not by intact cells. Extracts of T. foetus have been found to convert pyruvate to equimolar amounts of acetate, H2 and CO2. Formate was not metabolized by either intact cells or extracts, although an active hydrogenase was present. It is concluded that this protozoan possesses a mechanism of hydrogen formation similar to that found in the saccharolytic clostridial bacteria.

The fine structure of the plasma membrane and the mesosomes of Streptomyces coelicolor was studied by means of serial sections of aerial mycelium fixed in glutaraldehyde and osmium tetroxide, by negative staining of intact cells and cell fragments, and by freeze-etching. The plasma membrane as seen in freeze-etch preparations showed the typical features of bacterial plasma membranes: it was densely covered with small particles when viewed from the convex side. In serial sections it was possible to follow corresponding ‘ unit membranes’, suggesting the existence of spaces bounded by extensive lamellae. Negative staining revealed stacks of tubes and also spaces confined by lamellae. Vesicles were only rarely encountered. In freeze-etch preparations the mesosomes appeared mostly as clusters of vesicles, but lamellar and tubular regions were also found. It is suggested that ‘the mesosome’ with a uniform anatomy does not exist but that lamellae, tubes and vesicles arise from each other.

SUMMARY: Staphylococci incubated with calf thymus histone F2A or teat canal cationic protein bound more 131I bovine serum albumin than untreated bacteria. In experiments in vivo a similar increased binding of labelled albumin was observed in bacteria deposited in the teat canal of the cow and recovered 24 h. later. Antimicrobial cationic proteins may become attached to the surface of bacteria deposited in the teat canal. Incubation of staphylococci, containing 14C-labelled protoplasmic proteins, in isotonic saline with calf thymus histone F2A or teat canal cationic proteins caused a rapid release of the labelled protein followed by a slower release which continued for 5 h. Bovine serum albumin induced no greater protein leakage than isotonic saline.

SUMMARY: Extraction of Streptococcus salivarius nctc 8606 with formamide yielded a mixture of carbohydrate antigens which was fractionated by alcohol precipitation into a type antigen (containing rhamnose, glucose, galactose) and a group-like (z) antigen. The type antigen is related to type antigen III in group F streptococci. After partial hydrolysis five disaccharides and two trisaccharides were isolated and identified. Five of these were inhibitory in the quantitative precipitation of the type antigen.

Two other strains of Streptococcuss alivarius contained different group-like antigens and lacked the type antigen isolated from strain nctc 8606.

SUMMARY: The effects of temperature, pH, dilution rate and oxygen tension on the yield coefficient and respiration rate of Klebsiella aerogenes and Escherichia coli grown in continuous culture were studied. Reduced cell yields and increased oxygen uptake rates were obtained at low oxygen tension (2 to 5 mmHg) without any increase in the concentration of extracellular organic carbon. These effects and changes in the respiration rate with changes in the dilution rate are discussed in relation to the ‘energy efficiency’ of the cells.

SUMMARY: A new genus Gordona has been proposed for slightly acid-fast organisms which occur in sputa of patients with pulmonary disease and in soil. This genus is considered to contain ‘Mycobacterium’ rhodochrous-like organisms. The genera Mycobacterium and Gordona are characterized by absence of mycelium and slight or strong acid-fastness. The genus Gordona, shows characters intermediate between the genera Mycobacterium and Nocardia. It is distinguished from rapid-growing mycobacteria by its slight acid-fastness (weaker than Mycobacterium), absence of arylsulphatase activity at 2 weeks, ability to utilize sucrose as a sole carbon source and inability to utilize trimethylene diamine as a simultaneous nitrogen and carbon source. The genus is distinguished from nocardias by the absence of mycelium, ability to form acid from mannose, positive nitrate reduction and ability to utilize sucrose as a sole carbon source. It can be isolated from sputa of patients with lung cavities or bronchiectasis and from soil by prior treatment with alkali. The organisms are Gram-positive or variable; slightly acid-fast, that is, stained light pink or light violet by the Ziehl-Neelsen method; mycelium not formed; spores not formed; non-motile; aerobic; catalase-positive; oxidase-negative; acid formed from glucose by oxidation; growth occurs at 28° and 37° but not at 45°; growth at 2 to 3 days forming rough, reddish or pinkish colonies in air; occur as short rods; non-pathogenic for mice, rabbits, guinea pigs and chickens. Type species is Gordona bronchialis.