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Archives of Microbiology (v.191, #8)

Comparative study of Bifidobacterium animalis, Escherichia coli, Lactobacillus casei and Saccharomyces boulardii probiotic properties by Flaviano S. Martins; Aparecida A. Silva; Angélica T. Vieira; Flávio H. F. Barbosa; Rosa M. E. Arantes; Mauro M. Teixeira; Jacques Robert Nicoli (pp. 623-630).

The present work investigates some probiotic properties of four different microorganisms (Bifidobacterium animalis var. lactis BB-12, Escherichia coli EMO, Lactobacillus casei and Saccharomyces boulardii). In vitro and in vivo tests were carried out to compare cell wall hydrophobicity, production of antagonistic substances, survival capacity in the gastrointestinal tract of germ-free mice without pathological consequence, and immune modulation by stimulation of Küpffer cells, intestinal sIgA and IL-10 levels. In vitro antagonism against pathogenic bacteria and yeast was only observed for the probiotic bacteria B. animalis and L. casei. The hydrophobic property of the cell wall was higher for B. animalis and E. coli EMO, and this property could be responsible for a better ability to colonize the gastrointestinal tract of germ-free mice. Higher levels of sIgA were observed mainly for S. boulardii, followed by E. coli EMO and B. animalis, and only S. boulardii induced a significant higher level of IL-10. In conclusion, for a probiotic use, S. boulardii presented better characteristics in terms of immunomodulation, and B. animalis and L. casei for antagonistic substance production. The knowledge of the different probiotic properties could be used to choice the better microorganism depending on the therapeutic or prophylactic application.

Keywords: Probiotic; Lactobacillus casei ; Bifidobacterium animalis var. lactis BB-12; Escherichia coli EMO; Saccharomyces boulardii ; sIgA; IL-10

A potential antimicrobial treatment against ESBL-producing Klebsiella pneumoniae using the tellurium compound AS101 by Miriam Daniel-Hoffmann; Michael Albeck; Benjamin Sredni; Yeshayahu Nitzan (pp. 631-638).

Due to the extensive spread of antibiotic-resistant Klebsiella pneumoniae, the non-toxic immunomodulator, ammonium trichloro (dioxoethylene-o, o′) tellurate (AS101), was introduced for the first time in this study. Eleven strains of K. pneumoniae were tested: five were extended spectrum beta lactamase (ESBL)-producing strains and six were non-ESBL-producing strains. The MIC and MBC of ten strains were 9 μg/ml AS101 and 18 μg/ml for one strain. AS101 treatment inhibited bacterial growth in a dose-dependent manner on protein-rich media. No inhibition by AS101 was observed on poorer media. In combination with β-mercaptoethanol (2-ME) or cysteamine, AS101 inhibited bacterial growth in both types of media. Growth inhibition was also shown following AS101 treatment at both lag and log phases. Our data indicate that AS101 enters the bacterium through its porins, causing bacterial destruction. The mechanism of cell death was characterized using several techniques: (a) scanning electron microscopy showed that bacteria treated with AS101 or in combination with cysteamine exhibited evidence of cell-wall damage; (b) X-ray microanalysis demonstrated damage to Na/K pumps; and (c) transmission electron microscopy demonstrated cell lysis. These phenomena suggest that AS101 has antibacterial potential against K. pneumoniae infections.

Keywords: Klebsiella pneumoniae ; ESBL; Tellurium compound; Antimicrobial agents

Inhibition of uropathogens by lactic acid bacteria isolated from dairy foods and cow’s intestine in western Nigeria by Funmilola A. Ayeni; Bolanle A. Adeniyi; Samuel T. Ogunbanwo; Raquel Tabasco; Torsten Paarup; Carmen Peláez; Teresa Requena (pp. 639-648).

A total of 96 lactic acid bacteria (LAB) were isolated from African indigenous fermented products and cow’s intestines to study their inhibitory capability against multi-drug-resistant uropathogens. Escherichia coli accounted for approximately 45% of isolated uropathogens, followed by Staphylococcus spp. (20%). The Gram negative uropathogens were highly resistant to quinolones, co-trimoxazole, teicoplanin and some β-lactams, while the Staphylococcus spp. showed high resistance to aminoglycosides, β-lactams and macrolides. Twenty-four LAB isolates were selected based on their antimicrobial activity against two uropathogenic Staphylococcus aureus strains and bacteriocin production. LAB strains showing antimicrobial activity were grouped into smaller groups through amplified ribosomal DNA restriction analysis (ARDRA). Representative strains were identified as Weissella spp., Enterococcus faecium, Lactococcus lactis and Lactobacillus brevis through sequencing of 16S rDNA. The Weissella spp. and L. brevis strains demonstrated remarkable inhibitory activity against seven strains of Gram negative uropathogens. Two strains of L. lactis produced a bacteriocin-like inhibitory substance active against Lactobacillus sakei. In this study, an unusual high rate of co-trimoxazole, quinolones and macrolides resistance among uropathogens from south west Nigeria was discovered. Based on their sensitivity to Weissella spp., there is a potential for using these LAB as a natural approach for the protection against the uropathogens assayed.

Keywords: Lactic acid bacteria; Antimicrobials; Uropathogens; Antibiotic resistance

Characterization of Bacillus subtilis YfkE (ChaA): a calcium-specific Ca²⁺/H⁺ antiporter of the CaCA family by Makoto Fujisawa; Yuko Wada; Takahiro Tsuchiya; Masahiro Ito (pp. 649-657).

YfkE, a protein from Bacillus subtilis, exhibits homology to the Ca²⁺:Cation Antiporter (CaCA) Family. In a fluorescence-based assay of everted membrane vesicles prepared from Na⁺(Ca²⁺)/H⁺ antiporter-defective mutant Escherichia coli KNabc, YfkE exhibited robust Ca²⁺/H⁺ antiport activity, with a K _m for Ca²⁺ estimated at 12.5 μM at pH 8.5 and 113 μM at pH 7.5. Neither Na⁺ nor K⁺ served as a substrate. Mg²⁺ also did not serve as a substrate, but inhibited the Ca²⁺/H⁺ antiporter activity. The Ca²⁺ transport capability of YfkE was also observed directly by transport assays in everted membrane vesicles using radiolabeled ⁴⁵Ca²⁺. Transcriptional analysis from the putative yfkED operon using β-garactosidase activity as a reporter revealed that both of the yfkE and yfkD genes are regulated by forespore-specific sigma factor, SigG, and the general stress response regulator, SigB. These results suggest that YfkE may be needed for Ca²⁺ signaling in the sporulation or germination process in B. subtilis. ChaA is proposed as the designation for YfkE of B. subtilis.

Keywords: Bacillus subtilis ; Ca²⁺/H⁺ antiporter; CaCA family; Transporter

The analysis of core and symbiotic genes of rhizobia nodulating Vicia from different continents reveals their common phylogenetic origin and suggests the distribution of Rhizobium leguminosarum strains together with Vicia seeds by Estela R. Álvarez-Martínez; Ángel Valverde; Martha Helena Ramírez-Bahena; Paula García-Fraile; Carmen Tejedor; Pedro F. Mateos; Nery Santillana; Doris Zúñiga; Alvaro Peix; Encarna Velázquez (pp. 659-668).

In this work, we analysed the core and symbiotic genes of rhizobial strains isolated from Vicia sativa in three soils from the Northwest of Spain, and compared them with other Vicia endosymbionts isolated in other geographical locations. The analysis of rrs, recA and atpD genes and 16S–23S rRNA intergenic spacer showed that the Spanish strains nodulating V. sativa are phylogenetically close to those isolated from V. sativa and V. faba in different European, American and Asian countries forming a group related to Rhizobium leguminosarum. The analysis of the nodC gene of strains nodulating V. sativa and V. faba in different continents showed they belong to a phylogenetically compact group indicating that these legumes are restrictive hosts. The results of the nodC gene analysis allow the delineation of the biovar viciae showing a common phylogenetic origin of V. sativa and V. faba endosymbionts in several continents. Since these two legume species are indigenous from Europe, our results suggest a world distribution of strains from R. leguminosarum together with the V. sativa and V. faba seeds and a close coevolution among chromosome, symbiotic genes and legume host in this Rhizobium–Vicia symbiosis.

Keywords: Rhizobium ; Vicia ; Phylogeny; nodC gene; Peru; Spain

Resistance of the cell wall to degradation is a critical parameter for isolation of high quality RNA from natural isolates of Bacillus subtilis by Jean-Sébastien Guez; François Coutte; Anne-Sophie Drucbert; Nour-Eddine Chihib; Pierre-Marie Danzé; Philippe Jacques (pp. 669-673).

Natural isolates of Bacillus subtilis are known for their ability to produce a large panel of bioactive compounds. Unfortunately, their recalcitrance to conventional molecular techniques limits their transcript studies. In this work, difficulties to isolate RNA attributed to the cell wall were overcome, finally authorising powerful RT-PCR’s.

Keywords: RNA isolation; Bacillus subtilis ; Natural strain; Cell wall; Transcript analysis; RT-PCR

Amiodarone inhibits multiple drug resistance in yeast Saccharomyces cerevisiae by Dmitry A. Knorre; Tatiana N. Krivonosova; Olga V. Markova; Fedor F. Severin (pp. 675-679).

Amiodarone is a widely used antiarrhythmic drug. There is also evidence that amiodarone decreases multidrug resistance in human cell lines. In this paper, we have shown that amiodarone has similar effect on yeast, Saccharomyces cerevisiae, decreasing multiple drug resistance. Amiodarone stimulates the accumulation of ethidium bromide by inhibiting its efflux from the cells. The effect of amiodarone is much stronger on wild-type cells compared to the mutant with inactivated ABC-transporters. Interestingly, the action of amiodarone is additive with the one of chloroquine, a known inhibitor of ABC-transporters. We speculate that these findings could help in the development of antifungal drug mixes.

Keywords: Yeast; Amiodarone; Pleiotropic drug resistance; Multidrug resistance

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Archives of Microbiology (v.191, #8)

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Archives of Microbiology (v.191, #8)