Microbiology - Volume 131, Issue 9, 1985

Summary: True cellulase activity (i.e. degradation of crystalline cellulose) was markedly derepressed when cellobiose-grown cells were transferred to fructose or sorbitol, especially while the cells were adapting over many hours to these carbon sources. On the other hand, the long lag phase on glucose was not accompanied by derepression. Transfer to cellobiose resulted in low cellulase production. Growth on crystalline cellulose derepressed cellulase production. Addition of cellobiose (the preferred carbon source for growth) to cells adapting to fructose caused a rapid burst of growth and cessation of cellulase synthesis. After cells had adapted to growth on fructose or sorbitol, repression set in and, after a number of transfers, growth on these carbon sources yielded cellulase at a level even lower than with cellobiose or glucose. It appears that rapid growth on a soluble sugar such as cellobiose causes carbon source repression which is relieved during slow growth on crystalline cellulose or during the growth lag on fructose or sorbitol. The reason for the lack of cellulase derepression during the growth lag on glucose is unexplained.

Summary: Microbial death was studied under starvation conditions. The kinetics of cell death were described by dN/dt = kN +1, where N is the number of viable cells at time t, and k and are constants concerning growth or death of bacteria. Death in the decline phase of the culture also fitted the above equation, except for irregular oscillations with relatively short periods. This suggested that bacterial death in the decline phase was mainly caused by the same factor(s) as death under starvation conditions.

Summary: Forty-five strains of Staphylococcus hyicus subsp. hyicus and 36 strains of S. hyicus subsp. chromogenes were examined for bacteriolytic activity with the same assay system previously used in taxonomic studies on staphylococci. The two subspecies differed from each other chiefly in that for optimal lytic activity S. hyicus subsp. hyicus strains required a higher salt concentration in the test medium than S. hyicus subsp. chromogenes strains. The lack of lytic activity on B15TP1 medium was a major difference between S. hyicus and S. aureus, and the lack of activity on TP2P medium was a major difference between S. hyicus and S. intermedins. Penicillin-binding proteins (PBPs) were studied in 40 S. hyicus strains. The S. hyicus subsp. hyicus strains had only one PBP (mol. wt 79000) while the S. hyicus subsp. chromogenes strains had three distinct PBPs (mol. wts 84000, 82000 and 79000).

Summary: Two-dimensional thin-layer chromatography of whole-organism acid methanolysates of Mycobacterium chitae gives a characteristic pattern composed of -mycolate, a lower molecular weight -mycolate and characteristic pairs of polar mycolates. Analysis of alkaline methanolysates confirmed that these polar mycolates were derived from epoxymycolic acids. This pattern of mycolic acids has only been found previously in representatives of Mycobacterium farcinogenes, Mycobacterium fortuitum, ‘Mycobacterium peregrinum’, Mycobacterium senegalense and Mycobacterium smegmatis.

Summary: A study was made of Streptomyces rimosus and mutant strains to compare the phenotype of high and low oxytetracycline producers. Strains were identified using a probabilistic identification matrix for the genus Streptomyces. Mutant strains separated into two groups: high-titre strains and blocked mutants. The former identified with the S. rimosus cluster whereas the latter were not identified. Two further oxytetracycline producers identified with the Streptomyces lydicus cluster

Summary: Enterotoxigenic strains of Escherichia coli, which belonged to serogroups other than 0 6 and produced colonization factor antigen 11, usually produced only coli surface antigen 3 (CS3) and gave weak mannose-resistant haemagglutination of bovine erythrocytes. A non-autotransfer-ring plasmid, NTP165, from a strain of E. coli 0168.H16 coded for heat-stable enterotoxin, heat-labile enterotoxin and CS antigens. The CS antigens expressed after acquisition of plasmid NTPl65 depended on the recipient strain : a biotype A strain of serotype 0 6. H 16 expressed CS1 and CS3; a biotype C strain of serotype 0 6. H 16 expressed CS2 and CS3; strain K 12 and strain El9446 of serotype 0139. H28 expressed only CS3. An exceptional wild-type strain, E24377, of serotype 0139. H28 produced CS1 and CS3 when isolated; a variant of E24377 which had lostthe plasmid coding for CS antigens produced both CSl and CS3 after the introduction of NTP165.

Summary: The polyol gel Lutrol FC127 was used to solidify culture media. This gel liquefies as the temperature drops below a critical value for the concentration used. This property was used to recover whole colonies of Thermoactinomyces sp. for examination of the substrate mycelium by scanning electron microscopy.

Summary: Antisera against the Calvin cycle enzymes d-ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) and phosphoribulokinase (PRK) have been used in immunogold electronmicroscopy studies on cell sections of the cyanobacterium Chlorogloeopsis fritschii. RuBisCO antiserum consistently labelled the carboxysomes (polyhedral bodies) and the cytoplasm. PRK antiserum-labelling occurred in the cytoplasm but not in the carboxysomes. The data agree with in vitro enzyme localization studies, and confirm that both enzymes occur in the cytoplasm and that RuBisCO, but not PRK, also occurs in the carboxysomes of C. fritschii.

Summary: Lipoteichoic acid (LTA) from Lactobacillus casei YIT 90 18 or Lactobacillus fermentum YIT 01 59 augmented the resistance of C57BL/6 mice to infection with Pseudomonas aeruginosa, but conferred no resistance to Listeria monocytogenes. It is suggested that LTA was unable t activate macrophages.