Assay for beta-glucuronidase in species of the genus Escherichia and its applications for drinking-water analysis

Recently, Escherichia species other than Escherichia coli have been isolated from potable water. Environmental isolates as well as clinical isolates of E. adecarboxylata, E. blattae, E. fergusonii, E. hermannii, and E. vulneris were assayed for the enzyme beta-glucuronidase by using EC MUG medium and the Colilert system. None of the isolates were positive for the enzyme by either method.     

Assay for beta-glucuronidase in species of the genus Escherichia and its applications for drinking-water analysis.

Recently, Escherichia species other than Escherichia coli have been isolated from potable water. Environmental isolates as well as clinical isolates of E. adecarboxylata, E. blattae, E. fergusonii, E. hermannii, and E. vulneris were assayed for the enzyme beta-glucuronidase by using EC MUG medium and the Colilert system. None of the isolates were positive for the enzyme by either method.     

Leclercia adecarboxylata Gen. Nov., Comb. Nov., formerly known asEscherichia adecarboxylata.

The nameLeclercia adecarboxylata is proposed for a group of the family Enterobacteriacae previously known asEscherichia adecarboxylata. Leclercia adecarboxylata can be phenotypically differentiated from all other species of Enterobacteriaceae. The members of this species are positive for motility, indole production, methyl red, growth in the presence of KCN, malonate, beta-galactosidase, beta-xylosidase, esculin hydrolysis, gas production fromd-glucose, and acid production fromd-cellobiose,d-lactose, melibiose,l-rhamnose, adonitol,d-arabitol, dulcitol, and salicin; the strains were negative for Voges-Proskauer, citrate (Simmons), H₂S (Kligler), lysine and ornithine decarboxylases, arginine dihydrolase, phenylalanine deaminase, gelatinase, DNase, Tween-80 hydrolysis, and acid production from myoinositol and alpha-methyl-d-glucoside. Fermentation ofd-raffinose,d-sucrose, andd-sorbitol is variable with strains. DNA relatedness of 11 strains ofL. adecarboxylata to three strains including the type strain of this species averaged 80% in reactions at 65°C. DNA relatedness to other species in Enterobacteriaceae was 2%–32%, indicating that this species was placed in a new genusLeclercia gen. nov. The type strain ofL. adecarboxylata is ATCC 23216.     

Salt tolerance and glycerol accumulation of a respiration-deficient mutant isolated from the petite-negative, salt-tolerant yeast Zygosaccharomyces rouxii

A respiration-deficient (RD) mutant was isolated from the petite-negative, salt-tolerant yeast Zygosaccharomyces rouxii. One strain among sixteen glycerol-non-utilizing mutants exhibited vigorous liberation of CO2 but no uptake of O2. Furthermore, this strain lacked cytochrome aa3 and had a reduced level of cytochrome b. The few mitochondria found in cells of this strain contained few or no cristae. Salt tolerance and intracellular accumulation of glycerol by the RD strain were almost equal to that of the wild-type strain in media containing NaCl up to 2.5 M. In media with more than 3 M NaCl, the growth of the RD mutant was retarded and the intracellular accumulation of glycerol was depressed in spite of ample production.     

Degradation of Polycyclic Aromatic Hydrocarbons by a Newly Discovered Enteric Bacterium, Leclercia adecarboxylata

A bacterial strain, PS4040, capable of degrading polycyclic aromatic hydrocarbons for use as the sole carbon source was isolated from oily-sludge-contaminated soil. The 16S rRNA gene showed 98.8% homology to that of Leclercia adecarboxylata. Comparative molecular typing with the clinical strain of L. adecarboxylata revealed that there were few comigrating and few distinct amplimers among them.     

Role of dam and pups in the absence of nursing in CPB-B rats (rattus norvegicus)

In rats of the CPB-B strain, the female shows normal parturition behaviour and normal capacity of milk secretion, but the young - all born alive - die within few days of birth. Here, we report that this postnatal mortality is eliminated when CPB-B neonates are crossfostered to mothers of the Wu:Cpb strain; conversely, Wu:Cpb neonates (which are successfully reared by dams of their own strain) die within few days of birth when crossfostered to newly parturient CPB-B rats. It is suggested that pup mortality in CPB-B rats is due to inadequate maternal care resulting, supposedly, from susceptibility of the mother to disturbing environmental stimuli.     

Multidrug-resistant genes are associated with an 86-kb island in Acinetobacter baumannii

A strain of multidrug-resistant Acinetobacter baumannii that caused a 26% mortality rate in a French epidemic was characterized and compared with an antibiotic-susceptible strain of A. baumannii. The multiresistant strain carries many of its antibiotic-resistance genes on an 86-kb region, whereas the susceptible strain lacks these genes in a homologous region. Characterization of this multidrug-resistant A. baumannii strain highlights the limited options for current therapy and raises concerns for future treatment options in an era in which few novel antibiotics are being developed.     

Bacteria colonizing root nodules of wild legumes exhibit virulence-associated properties of mammalian pathogens

Bacteria not proficient in nitrogen fixing symbiosis were proven able to invade root nodules of three wild legumes of the genus Hedysarum in Algeria and to be multiplying in these in place of the natural rhizobium symbionts. The involved species featured taxa known as human pathogens including: Enterobacter cloacae, Enterobacter kobei, Escherichia vulneris, Pantoea agglomerans and Leclercia adecarboxylata. A direct screening of the phenotypic determinants of virulence using human cultured cells tested positive for the traits of cytotoxicity, vital stain exclusion and adhesion to epithelia. Antibiogram analyses revealed also a complex pattern of multiple antibiotic resistances. The data suggest that legume root nodules can be a site of survival and of active multiplication for populations of mammalian pathogens, which could thus alternate between the target animal and a number of neutral plant hosts. The worldwide distribution of as yet uninvestigated legumes raises the concern that these represent a general niche that could enhance the hazards posed by microorganisms of clinical nature.     

Detection and identification of bacteria using antibiotic susceptibility and a multi-array electrochemical sensor with pattern recognition

This work proposes the use of amperometric signals generated by a 96-well multi-array dissolved oxygen multi-electrode sensor (DOX) coupled with principal component analysis for continuous monitoring, identification and differentiation of bacteria. Two types of differentiation mechanisms were tested: (1) direct monitoring of respiratory activity via oxygen consumption and (2) quantification of the effect of three broad-spectrum antibiotics on bacteria growth and respiration over time. Five species of bacteria were examined including: Escherichia coli, Escherichia adecarboxylata, Comamonas acidovorans, Corynebacterium glutamicum and Staphylococcus epidermidis. The addition of small concentrations of antibiotics to the growth medium alters the oxygen consumption of the cells and a unique fingerprint is created for a specific cell. This fingerprint is shown to evolve over a specific concentration range that is dependant of instrumental constraints of the DOX system. The application of principal component analysis (PCA) to classify the data was also examined. It was shown that bacteria could be classified simply by their oxygen consumption rates over a varying concentration range. Discrimination between species can also be increased by the effects of the antibiotics on the oxygen consumption of varying concentrations of cells. The proposed DOX-PCA system illustrates a generic template that can be tailored to meet specific research goals by the selection of specific cell/antibiotic combinations and concentrations.     

Recovery of temperate Desulfovibrio vulgaris bacteriophage using a novel host strain

A novel sulfate-reducing bacterium (strain DePue) closely related to Desulfovibrio vulgaris ssp. vulgaris strain Hildenborough was isolated from the sediment of a heavy-metal impacted lake using established techniques. Although few physiological differences between strains DePue and Hildenborough were observed, pulse-field gel electrophoresis (PFGE) revealed a significant genome reduction in strain DePue. Comparative whole-genome microarray and polymerase chain reaction analyses demonstrated that the absence of genes annotated in the Hildenborough genome as phage or phage-related contributed to the significant genome reduction in strain DePue. Two morphotypically distinct temperate bacteriophage from strain Hildenborough were recovered using strain DePue as a host for plaque isolation.     

Extracellular amylase synthesis by Bacillus globisporus BH-1b

Despite the prevalence of starch-hydrolyzing enzymes in bacilli, relatively few have been studied in detail. In an attempt to isolate an effective α-amylase-producing strain, Bacillus globisporus BH-1b has been isolated. The strain requires few nutritional supplements and shows induction in the presence of galactose. 2% potassium nitrate and pH 7.2 emerged as optimum for the fermentation medium. The durability of the enzyme has also been tested at a low pH and a high temperature.     

Isolation of an isoflavone-metabolizing, Clostridium-like bacterium, strain TM-40, from human faeces

Recently, the biological effects of isoflavones have attracted much attention. Intestinal microbiota plays an important role in the metabolism and bioavailability of isoflavones. However, few reports have discussed intestinal bacteria that metabolize daidzein into dihydrodaidzein. In this study, we isolated the dihydrodaidzein-producing intestinal bacterium TM-40 from a healthy boy's faeces. The bacteria from faecal samples were incubated with daidzein. Among all tested bacteria, one strain (strain TM-40) produced dihydrodaidzein both from daidzein and daidzin. However, in our experimental conditions, strain TM-40 did not produce equol from daidzein. The 16S rRNA partial sequence of strain TM-40 (AB249652) exhibited a 93% similarity to that of Coprobacillus catenaformis (AB030218). This strain seems to be a new species.     

Molecular and biological characterization of the CIBMUQ/HDC strain, a reference strain for Colombian Toxoplasma gondii

There are few reports about characterization strains of Toxoplasma gondii that analyze the differences between isolates from Europe or United States with those obtained in South America. The current study analyzes virulence data from the mouse model, the gene SAG2 polymorphism by PCR-RFLP and microsatellite analysis in a single Colombian isolate. The strain was isolated from blood of a child with congenital toxoplasmosis, living in Armenia, Colombia. Analysis of virulence in the mouse showed that this strain has an LD100 of 10 tachyzoites. Both methods of genetic characterization demonstrated that this strain belonged to the clonal type 1 and was called HOM/CTCO/2002/CIBMUQ/BL/HDC (brief name: CIBMUQ/HDC). The CIBMUQ/HDC strain is the first Colombian strain available as a reference strain for national and international researchers.     

Plasmodium falciparum: in vitro induction of resistance to aminopterin

Plasmodium falciparum parasites were grown on microplates in the presence of aminopterin. The FCR-8 strain was more sensitive to aminopterin than a Richards strain and died within 1 week of treatment. A few parasites of the Richards strain survived treatment and developed normal parasitemias. This strain was resistant to aminopterin at concentrations not higher than those used for its selection. Removal of aminopterin did not affect the growth of the resistant variant, showing that it was not aminopterin dependent. Aminopterin affected the sensitive parasites by interfering with nucleic acid synthesis, whereas protein synthesis was not impaired. Gametocytogenesis was unaffected by aminopterin.     

An ovulation inducing agent containing clomiphene citrate causes DNA-strand breaks without SOS responses in Escherichia coli

Effects of Clomid, an ovulation-inducing drug containing clomiphene citrate, on Escherichia coli were investigated. Radiation-sensitive mutants, uvrA and recA, were more sensitive to Clomid than the parental wild-type strain. DNA synthesis in these two strains was more depressed by Clomid than that in the wild-type strain. Clomid caused DNA-strand breaks, but few SOS responses such as mutation, induction of prophage and expression of the umuC+ gene were induced.     

Complete genome sequence of Mycobacterium phlei type strain RIVM601174

Mycobacterium phlei is a rapidly growing nontuberculous Mycobacterium species that is typically nonpathogenic, with few reported cases of human disease. Here we report the whole genome sequence of M. phlei type strain RIVM601174.     

Clostridium botulinum Type F in the Soil of Argentina

One strain of Clostridium botulinum belonging to type F has been isolated from a soil sample taken in Buenos Aires Province, Argentina. Comparative studies carried out with strain Langeland of C. botulinum type F have shown a few differences between the two strains.     

Comparison of the cell envelope structure of a lipopolysaccharide-defective (heptose-deficient) strain and a smooth strain of Salmonella typhimurium.

The cell envelope structure of Salmonella typhimurium LT2, which has a heptose-deficient lipopolysaccharide (LPS), is significantly different from that of an isogenic strain with a normal LPS. The rough strain, when examined by freeze-etching, lacks most surface structures that are routinely present in the smooth strain (surface particles and flagella) and has few transmemberane studs in the cytoplasmic membrane (those present are generally found in aggregates), and the outer membrane cleavage is substantially stronger than that of the smooth strain. These envelope differences were independent of both growth temperature and culture age. Examination of ultrathin sections indicated that the rough strain has an outer membrane which forms a much more defined double-track artifact than the smooth strain. The addition of MgCl2 to the growth medium of the rough strain decreased the extent of outer membrane cleavage, and flagella became evident in freeze-etched preparations. The presence of supplemental MgCl2 in the growth medium, which resulted in these morphological changes in the rough strain, also produced growth at a previously restrictive temperature and a decrease in the leakage of periplasmic enzymes. The smooth strain was unaltered morphologically or physiologically by MgCl2 under identical conditions. It is suggested that the outer membrane of the rough strain is more planar.     

Selective Isolation of Fusarium graminearum Mutants Derepressed for Production of beta-Glucosidase

A strain of Fusarium graminearum produced extracellular beta-glucosidase (beta-d-glucoside glucohydrolase [EC 3.2.1.21]) subject to carbon catabolite repression. Derepressed mutants were selectively isolated by the use of 2-deoxyglucose, a nonmetabolizable catabolic repressor. On each plate of cellobiose and 2-deoxy-glucose inoculated with 10 spores and irradiated with UV light, a few colonies emerged. Comparative growth experiments with one of the derepressed mutants and the parent strain showed that the mutant produced beta-glucosidase in the presence of glucose. Furthermore, the same mutant produced more beta-glucosidase than did the wild-type strain on cellobiose alone.     

Scrapie strains maintain biological phenotypes on propagation in a cell line in culture.

Bovine spongiform encephalopathy (BSE) and its human equivalent, variant Creutzfeldt-Jakob disease (vCJD), are caused by the same strain of infectious agent, which is similar to, but distinct from, >20 strains of their sheep scrapie homologue. A better understanding of the molecular strain determinants could be obtained from cells in monoculture than from whole animal studies where different cell targeting is commonly a strain-related feature. Although a few cell types can be infected with different strains, the phenotypes of the emergent strains have not been studied. We have cured the scrapie-infected, clonal SMB cell line with pentosan sulfate, stably re-infected it with a different strain of scrapie and shown that biological properties and prion protein profiles characteristic of each original strain are propagated faithfully in this single non-neuronal cell type. These findings attest to the fact that scrapie strain determinants are stable and host-independent in isolated cells.