- Volume 74, Issue 2, 1973

SUMMARY: Protein synthesis and translocation of l-[14C]leucine, d-[14C]glucose and inorganic 32P were enhanced in cultures of Sclerotium rolfsii Sacc. grown on medium supplemented with 0·5% lactose. Ethanol (2%, v/v) inhibited translocation but not protein synthesis. Neither lactose nor ethanol affected the uptake of radioactive substances by the fungal mycelium. Cycloheximide applied to the colony margins prevented sclerotium formation and protein synthesis without inhibiting translocation. It was concluded that translocation and protein synthesis in S. rolfsii are independent processes and are both essential for sclerotium formation.

SUMMARY: Lipopolysaccharides were obtained from a number of strains of yellow-pigmented rods identified as Cytophaga species and from representative strains of fruiting myxobacteria. The major monosaccharide components of the lipopolysaccharides were identified by paper chromatography and subsequent analysis. Most preparations contained ribose, mannose and galactose and no major differences were seen between the composition of fruiting and non-fruiting myxobacterial lipopolysaccharides. Other sugars detected included rhamnose, glucose, glucosamine and galactosamine, but some of the polymers may also contain small amounts of other monosaccharides which have not yet been identified. The chemical similarity of the lipopolysaccharides to analogous polymers from other Gram-negative bacteria confirms the belief from cytological studies that the cell wall of myxobacteria resembles that of typical Gram-negative prokaryotes.

SUMMARY: The fatty acid compositions of three strains of Pseudomonas multivorans and three of P. kingii were determined by gas-liquid chromatography. The major fatty acids identified were 16:0, 16:1, 18:1, 3-OH 14:0, 3-OH 16:0 and cyclopropane acids 17 Δ and 19 Δ. The fatty acid compositions of these strains were similar to the acids identified in sixteen clinical isolates of the P. multivorans (P. cepacia)/P. kingii group’. These data support the current view that P. multivorans and P. kingii are identical species.

SUMMARY: Protoplasts of a strain of Pythium (prl 2142) could be obtained by incubating the mycelium with a combination of helicase and cellulase in the presence of an osmotic stabilizer. This process was inhibited when organic compounds were used as osmotic stabilizers but stimulated by pretreatment of the mycelium with a detergent. The most effective detergent was Triton X100. Regeneration of protoplasts could be demonstrated in liquid or in solid media, but less than 30% of the protoplasts were able to grow into new mycelium. In contrast to protoplast formation, regeneration was inhibited by the inorganic salts used as osmotic stabilizer. The results suggest that the hyphal wall of Pythium is covered with a protective layer of lipid material.

SUMMARY: A possible method using fluorescent brighteners for estimating the rate of wall accumulation by regenerating protoplasts is described. The relationship between the amount of wall and brightener adsorption was linear. Phases of slow and rapid brightener adsorption, thought to be correlated with chain and hypha formation respectively, were found during regeneration. The length of the slow phase varied according to the composition of the regeneration medium.

SUMMARY: Staining a marine bacterium with Ruthenium Red and Alcian Blue demonstrated an extracellular, compact acidic polysaccharide layer, which was involved in bacterial adhesion to surfaces. The adhesive substance was present on suspended bacteria and appeared to assist adhesion when they were forced into contact with a suitable surface. Bacteria, which had attached to a surface naturally, produced a secondary fibrous acidic polysaccharide, which probably developed from the primary polysaccharide, and could eventually replace it.

A high pH in the growth medium almost totally prevented the appearance of primary polysaccharide in preparations of naturally attached bacteria, which were surrounded by the reticular secondary polysaccharide, and adhesion was not impaired. In contrast to naturally attached bacteria, those forcibly attached were surrounded by primary polysaccharide.

High temperature lowered the number of bacteria attached, relative to culture density, but did not affect the appearance of the adhesive substance.

SUMMARY: In a few phloem cells in root nodules of clover (Trifolium repens L.) and salivary glands of Euscelis lineolatus Brullé, which were naturally or experimentally infected by the mycoplasmas of clover phyllody, rod-shaped virus-like particles were found which had at least one rounded end. These particles had a diameter of 27 ± 3 nm, a dense core of diameter 16 ± 2nm and a clear axis. Their mean length was between 50 and 90 nm. Even when they were free in the phloem sap of the plant or in the haemolymph of the insect they were in the vicinity of some mycoplasmas. Sometimes they were crowded in a monolayer inside the cytoplasm of the plant cell. They were also found in the form of a rosette around some mycoplasmas which seemed degenerated. The occurrence, size, shape, internal structure and position of these virus-like particles is illustrated; their nature and pathogenicity in comparison with Mycoplasmatales Virus laidlawii 1 and the virus-like particles sometimes associated with plant pathogenic mycoplasmas is discussed.

SUMMARY: The particulate NADH oxidase activity of Bacillus brevis is inhibited by tyro-cidine and the kinetics of inhibition indicate that the NADH dehydrogenase region is the primary site of action. A decrease in NADH oxidase activity of electron transport particles and of NADH oxidase activity of whole organisms occurs in batch culture in the later stages of growth when production of tyrothricin increases. That respiration exhibited by growing cells takes place via the respiratory electron-transport system is indicated by the similarities in levels of activity and cyanide sensitivity of endogenous and NADH oxidation of growing cells. Exponential growth on glycerol asparagine media is diphasic, a slower growth rate commencing as the O2 tension of the culture approaches zero and tyrothricin production increases. Molar growth yield data based on overall measurements of growth related to O2 uptake in batch culture lead to low ATP/O ratios. In an attempt to determine Y 0 and ATP/O ratios under optimum conditions of growth a method is described which was based entirely on the growth and respiratory activity of exponentially growing cells. Such measurements led to higher values for Y 0 and to ATP/O ratios approaching 3, indicating the participation of three sites of phosphorylation during exponential growth. Tyrocidine and DNP inhibited growth, the tyrocidine at concentrations similar to those produced at the end of the exponential growth phase. Y 0/Y ATP ratios (ATP/O ratios) on glycerol asparagine media were lower than on peptone yeast extract medium which yielded no tyrothricin, a possible indication that some form of uncoupling occurs in organisms grown on glycerol asparagine medium which does not yield tyrothricin.