- Volume 74, Issue 1, 1973

SUMMARY: A survey has been made of the nature of phosphorylated wall polymers in a number of micrococci. Polymers found include typical glycerol and ribitol teichoic acids (polymers of glycerol phosphate or ribitol phosphate) having different sugar substituents. atypical teichoic acids in which the repeating unit comprises glycerol phosphate and N-acetylglucosamine i-phosphate, and sugar i-phosphate polymers. Distinct chemogroups can be recognized based on the composition and structure of the wall polymers.

SUMMARY: The sporogonic stages and spores of Thelohania and of Plistophora from Simulium ornatum larvae were examined with the electron microscope. The two species of Thelohania studied appeared morphologically similar apart from spore size and the number of polar filament coils within the mature spore. The first species, Thelohania minuta (Gassouma, 1972), had four to five coils, while the second, T. canningi (Gassouma, 1972), had nine to ten. These mature filaments were found to have an internal structure and their polar cap was not directly attached to the internal spore wall. The varied membrane systems, including polaroplast, Golgi apparatus and endoplasmic reticulum of each stage are described. The Plistophora species, Plistophora tillingbournei (Gassouma, 1972), had 20 to 21 polar filament coils within the mature spore. The complex wall of sporoblast and spore of this species is compared with the smooth one found in the two Thelohania species.

SUMMARY: An antiserum prepared against a strain of Lactobacillus acidophilus gave a reaction of identity with HCl extracts of strains of lactobacilli, some pediococci and leuconostocs and Staphylococcus aureus. The antigenic determinant, isolated from a strain of L. casei ro–94 was identified as a membrane glycerol teichoic acid. Purified membrane lipoteichoic acids from Lactobacillus serological groups A, B, C, D and F and streptococcal polyglycerophosphate also reacted with the antiserum. The antigen-antibody reaction was partially inhibited by α-glycerophosphate and strongly inhibited by glycerol-phosphoryl-glycerol-phosphoryl-glycerol, but was not inhibited by glucose. It was concluded that the antiserum was reacting with the common polyglycerophosphate backbone of the membrane teichoic acids in the reacting strains.

SUMMARY: The germination process of spores of several fungi which require exogenous energy-sources was initiated in non-amended natural soil, a medium deficient in energy-yielding substrates. As measured by subsequent germination time on sterilized soil, this phase accounted for about 8 to 25% of the total germination time. In conidia of Penicillium frequentans it was irreversible, was inhibited by temperatures of 1°C and was dependent on water alone. Continued progress towards germ-tube formation required exogenous energy-yielding nutrients. When incubation on sterilized soil was interrupted by exposure to non-amended natural soil or a model system designed to imitate the microbial energy-source sink of natural soil, progress towards germination ceased in several fungi. Progress already made towards germination was maintained if the exposure to deprived conditions was short (about 3 days or less), but if longer the germination process reverted towards the water-dependent phase. The reversal, in P. frequentans conidia, paralleled the loss of 14C from spores labelled with [14C]glucose. When 14C-labelled conidia were incubated in an artificial nutrient sink, the label lost was about equally divided between 14CO2 and non-gaseous 14C-labelled metabolites. Pretreatment of P. frequentans conidia in water stimulated uptake of [14C]glucose. The results support the view that soil fungistasis in many instances is caused by nutrient deprivation.

SUMMARY: Crude cell-free amino acid-incorporating systems derived from a variety of enterobacterial species are not uniform in their ability to translate RNA of the coliphages Qβ or MS2. Escherichia coli, Shigella alkalescens and to a lesser extent Citrobacter freundii translate effectively under standard conditions, but Salmonella typhimurium, S. pomona and Proteus morganii do not. Ineffective species do not generally inactivate phage RNA faster than effective ones, and they are as effective as E. coli in their general capacity for mRNA translation. This was judged in representative species by the incorporation of phenylalanine and leucine labels as directed by polyuridylate or mRNA of phage-infected S. typhimurium, and from the relative incorporation of methionine label into the normal initiating N-formyl-methionine residues of polypeptides. The ribosomal rather than the soluble components appear responsible for ineffectiveness in translation.

SUMMARY: Genes which are involved in anaerobic growth with nitrate or nitrite as terminal electron acceptor in Pseudomonas aeruginosa were mapped by interrupted mating and linkage analysis after conjugation. Times of entry were mostly consistent with the linkage frequencies. Late markers were not located precisely. A gene order was obtained for the genes involved in dissimilatory nitrate (nar) and nitrite reduction (nir) and anaerobical growth (ana) and for some already known auxotrophic genes. A mutant unable to grow aerobically (aer) was found. The aer mutation appeared to be an early marker. The cytochrome spectra of nir mutants and part of the cytochrome oxidase activities were abnormal in that haem d was absent. Most of the nar mutants were pleiotropic. Nar A mutants were affected in assimilatory and dissimilatory nitrate reductase, and nar B, nar D and nar E mutants lacked assimilatory and dissimilatory nitrate reductase and xanthine dehydrogenase. In nar D mutants high concentrations of molybdate restored xanthine dehydrogenase and assimilatory and dissimilatory nitrate reductase and, consequently, anaerobic growth. Just as in the aer mutants, which had a normal respiratory system, the denitrifying system and the cytochrome system in ana mutants were normal. It is therefore unlikely that ana and aer mutants synthesize defective energy generating systems.

SUMMARY: Addition of histidine to cultures of Staphylococcus aureus strain Wood 46 in a synthetic amino acid medium induced α-toxin formation, intracellularly within 10 min, and extracellularly within 15 min. The induction was inhibited by actino-mycin D, chloramphenicol, sodium azide and sodium nitrite. Histidinol behaved like histidine but several histidine analogues were without inductive properties. Histamine, which was metabolized to N-acetylhistamine, inhibited growth and α-toxin production in media without histidine, but its effect was overcome by histidine or histidinol.

The culture fluids were examined by polyacrylamide gel electrophoresis. Precipitation with trichloracetic acid was used for concentration of the α-toxin, active toxin being recovered from the precipitate by dissolving in urea followed by heat precipitation.

Three proteins appeared extracellularly in addition to α-toxin after induction with histidine.

SUMMARY: Chemotaxis of a bacterium such as Escherichia coli is assayed by measuring the number of organisms attracted into a capillary tube containing an attractant. Rate of bacterial accumulation in capillaries and a concentration-response curve for l-aspartate taxis are presented and interpreted, and the effect of bacterial concentration is reported. Other parameters of the assay were studied, such as the volume of fluid in the capillary and the size of the capillary opening. The concentration gradient of chemical was also described. Escherichia coli chemotaxis requires EDTA to allow motility, a buffer to maintain the pH at its optimum near neutrality, and l-methionine if it cannot be synthesized. Under certain conditions there is stimulation by inorganic ions, either by K+ or, less effectively, by Na+. Chemotaxis is dependent on temperature, there being a 20-fold increase in the number of bacteria accumulating in a capillary when the temperature is raised from 20 to 30 °C.

SUMMARY: Examination of the growth kinetics of Bacterium NCIB 8250 in a two-stage continuous culture showed that growth of this organism on phenol could be accounted for by the Haldane function for substrate inhibition. The magnitude of the constants (K s < 1 mg/l; and K i, 110 mg/l) was such that inhibition was the dominant factor governing the growth of the organism even at substrate concentrations less than 10 mg/l. The maintenance requirement of the organism was high (0.24 to 0.28 g/g h), probably owing to the energy requirement for rupture of the aromatic nucleus of the substrate.

The influence of such kinetics on the treatment of inhibitory wastes by the activated-sludge process is discussed. Extreme sensitivity of the experimental system to slight changes in operating conditions was explicable by a mathematical model using constants found in the investigations.