- Volume 131, Issue 7, 1985

Summary: Two monoclonal antibodies specific for type-1C fimbriae of Escherichia coli were produced. In enzyme-linked immunosorbent assay and immunoblotting the antibodies, which were of the IgG1 isotype, reacted with type-1C, but not with P or type-1 fimbriae of E. coli strain KS71. Immunoblotting and immunoprecipitation of crude fimbrial extracts from 25 strains invariably gave an apparent molecular weight of 17000 for the type-1C fimbrillin. A total of 313 E. coli strains, isolated from patients with extraintestinal infection or from faeces of healthy children, were screened for the presence of type-1C fimbriae using both the monoclonal and polyclonal antibodies. Of these, 45 (14%) strains had type-1C fimbriae, with the highest frequency (27%) on strains isolated from patients with pyelonephritis. No faecal strain had type-1C fimbriae, and the frequency on the other diagnostic groups ranged from 11 to 15%. Thus, no direct correlation between type-1C fimbriae and bacterial virulence in human extraintestinal infections was found. Type-1C fimbriae were detected on only a few E. coli serotypes, notably on all O6:K2:H1 and O22:K13:H1 strains tested.

Summary: Interactions between group 1 acholeplasmaviruses and their host cells were studied. Acutely infected, chronically infected and uninfected cultures of Acholeplasma laidlawii strain JA1 were compared by their growth in broth and on agar, by the sensitivities of the uninfected and chronically infected cells to representatives of each of the three groups of acholeplasmaviruses, and by their SDS-PAGE polypeptide profiles. Acutely infected cells resembled uninfected cells by these criteria, except for the fact that progeny virus was being released. Two types of chronically infected cells were found: rapid growers (the same doubling time as uninfected cells) and slow growers. The latter resembled uninfected cells, except for their slower growth and low-level release of virus, and the former was resistant to group 1 viruses and had a unique polypeptide profile. These biological characterizations help to establish the non-lytic, non-cytocidal cycle of the group 1 acholeplasmaviruses.

Summary: Murine hybridomas secreting monoclonal antibodies to Mycobacterium bovis were produced and three soluble antigens were identified using radioimmunoassays and immunoblotting from polyacrylamide electrophoresis gels. Antibody MB3 (IgM, k chain) reacted with 20-100 kDal antigens produced by all mycobacterial strains examined while antibody MB5 (IgG2a, k chain) identified a 29·8 kDal antigen detected in field isolates of M. bovis and M. bovis strains Vallée and AN5. There was insignificant binding to M. bovis BCG, M. tuberculosis, M. microti, M. africanum, M. avium or M. paratuberculosis. Monoclonal antibody MB17 (IgA, k chain) reacted with a 17·4 kDal antigen present in M. bovis, M. tuberculosis and M. microti. Absorption of monoclonal antibodies with antigens from different species of Mycobacterium confirmed the specificities of MB3 and MB5 but the binding of MB17 was inhibited to some extent by all the extracts examined. The antigen identified by MB3 was present in purified protein derivative (PPD) from M. bovis, M. paratuberculosis and M. avium but antigens identified by MB5 and MB17 were not detected in these reagents.

Summary: In addition to an excreted phosphatase, Lysobacter enzymogenes produces a distinctly different alkaline phosphatase which remains associated with the cells. It is the only major phosphatase contained in the cells. Little enzyme activity is found in whole cells using the standard assay with p-nitrophenyl phosphate as the substrate, but maximum activity can be obtained after toluene or detergent treatment, or mechanical disruption of the cells. The phosphatase is not released from the cells by osmotic shock, or by treatment with MgCl2 or high LiCl concentrations. It is associated with the particulate fraction in cell-free extracts and detergents solubilize the enzyme from intact and broken cells. Separation of the inner and outer membranes of the cells by sucrose gradient centrifugation showed that most, if not all, of this phosphatase is located in the outer membrane.

Summary: The production of extracellular β-D-fructanase by several strains of Streptococcus mutans was studied in continuous culture. When glucose was the limiting nutrient, S. mutans K1-R and OMZ176 accumulated fructanase to maximum levels at low growth rates (dilution rate 0·05-0·10 h−1), due to the longer residence times of the bacteria in the culture vessel under these conditions. Extracellular fructanase activity was greater than has been previously reported for batch cultures. The rate of fructanase production for both S. mutans strains K1-R and OMZ176 increased with increasing growth rate when glucose was limiting. Under conditions of glucose sufficiency, the rate of fructanase production was always lower than in cultures where glucose was limiting, irrespective of the growth rate. Cultures of S. mutans Ingbritt (serotype c) grown with sorbitol- or glucose-limitation synthesized fructanase at a very low basal rate. When fructose was the limiting carbohydrate the enzyme was induced with a maximum rate of production occurring at a dilution rate of 0·40 h−1. Strains of S. mutans from other serotypes (a, d, d/g) were either not affected by changing the limiting sugar from glucose to fructose or else fructanase activity was slightly decreased in the fructose-limited medium. Fructanases from various strains of S. mutans readily hydrolysed (2 → 6)-β-D-fructans, but all possessed the ability to hydrolyse (2 → 1)-β-D-fructans to varying degrees.

Summary: Patterns of in vitro translation products from isolated mRNA and in vivo polypeptide accumulation in synchronized cultures of Cylindrotheca fusiformis were analysed by two-dimensional gel electrophoresis. The way in which the availability of silicon, the specific cell cycle stage, or the illumination conditions affected the pattern of gene expression was distinguished by comparing the timing of polypeptide and mRNA accumulation in cultures synchronized by two different methods. A rapid and dramatic shift in the relative abundance of in vitro translation products from mRNA followed either the removal or the readdition of silicate to the media as well as the transition from dark to light. Eleven mRNAs appeared to be expressed specifically between mid-S phase and cell separation, as their increase was observed at this stage in both synchronies. In addition, three mildly acidic polypeptides from the soluble protein fraction of C. fusiformis, each representing about 0·05% of the total protein, increased several-fold between mid-S and cell separation. Thus, silicon appears to affect gene expression both directly and, due to its effect on cell cycle progression, indirectly. Both effects are primarily at a level before translation.

Summary: The character state data for clusters defined at the 83% simple matching coefficient (SSM ) similarity level in a previous phenetic classification were used to construct a probabilistic identification matrix for Streptoverticillium species. The 24 phena included consisted of 10 clusters containing from 2 to 17 strains and 14 single-member clusters. Characters most diagnostic for the clusters were selected from the 185 used in the classification, using previously developed computer programs for determination of character separation indices (CHARSEP) and selection of group diagnostic properties (DIACHAR). The resulting matrix consisted of 41 characters x 24 phena, and identification scores, provided by a program for the identification of unknowns against an identification matrix (MATIDEN), were used for its evaluation. Cluster overlap, calculated by a program for determination of overlap between groups in a matrix (OVERMAT), was generally very small, and the best identification scores possible for most typical examples of each group (MOSTTYP program) were very satisfactory. Input of test data for randomly selected cluster representatives resulted in correct identifications with good scores for the three coefficients provided by the MATIDEN program.

Summary: Mycobactins were isolated from five strains designated Mycobacterium farcinogenes and a similar number designated Mycobacterium senegalense following growth under conditions of iron-limitation. These lipid-soluble iron-chelating compounds were characterized by a combination of thin-layer and high-performance liquid chromatography. The mycobactins from both the slow-growing M. farcinogenes and the rapidly-growing M. senegalense strains proved impossible to differentiate both from each other and from those produced by strains of Mycobacterium fortuitum, indicating a close relationship between all three species. However, Nocardia farcinica, previously implicated with the bovine farcy strains, produced a different mycobactin which was easily distinguished by thin-layer chromatography alone.

Summary: Eleven out of 43 strains of Clostridium sordellii from clinical sources did not produce lecithinase activity and were not toxic to mice. However, these strains did belong to the C. sordellii group and could readily be differentiated from C. bifermentans and C. difficile on the basis of DNA-DNA homologies, carbohydrate fermentation patterns, enzyme activities, GLC analysis of fatty acid fermentation products and the electrophoretic analysis of whole cell protein extracts.