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Archives of Microbiology (v.191, #9)
Signal peptide of Arabinosidase enhances secretion of interferon-α2b protein by Bifidobacteria longum by Qiwen Deng; Weiseng Zeng; Zhijian Yu (pp. 681-686).
Bifidobacteria can potentially be used for gene therapy. Here, we reported that 65% of the total hIFN-α2b produced from Bifidobacteria longum transformed with pBAD-SPIFN plasmids encoding a fusion protein of the arabinosidase signal peptide and human IFN-α2b (hIFN-α2b), was secreted. For B. longum transformed with pBAD-IFN plasmids (hIFN-α2b without the signal peptide), only 15% of the total IFN-α2b was secreted and western blotting and N-terminal amino-acid sequence analysis revealed cleavage of the arabinosidase signal peptide from the secreted hIFN-α2b. Moreover, the active level of the secreted hIFN-α2b in the supernatant of B. longum transformed with pBAD-SPIFN plasmids was over 1,000 IU/ml commercial rhIFN-α2b. Hence, the arabinosidase signal peptide can enhance the secretion efficiency of IFN-α2b from B. longum.
Keywords: Bifidobacteria ; Bifidobacterium longum ; Interferon-α2b; Signal peptide; Endo-1,5-alpha-l-arabinosidase
Anticandidal cytotoxicity, antitumor activities, and purified cell wall modulation by novel Schiff base ligand and its metal (II) complexes against some pathogenic yeasts by Neveen S. Geweely (pp. 687-695).
The preparation of metal (II) complexes [CoCl2·6H2O, Ni(CH3COO)2·4H2O, Cu(CH3COO)2·2H2O, and Zn (CH3COO)2 ·2H2O] with 2[N-(cinnamlidene) amino]-5-nitro phenol as a novel ligands and their biological evaluation against candida species was studied. The inhibitory effects of the tested metal complexes were tested against six pathogenic yeasts (Candida albicans, C. fructus, C. glabrata, C. oleophila, C. parapsilosis, and C. tropicalis). The effect of the most efficient metal complex (Zn(II) complex) was more pronounced at 1.25 μg/ml, while Ni(II) complex was exhibited the least suppressive effect. Co(II) and Zn(II) complexes act as potential antitumor agents, while Zn(II) complex has shown promising cytotoxic activity with slow candidal respiration rate. Addition of Zn(II) complex leading to suppression of cell wall components in all candidal cells accompanied with leaking out of amino acids. Purification of the cell wall mannoprotein of C. glabrata treated with Zn(II) complex was established, resulting one pure fissured protein peak. Cell wall protein modulation was showed by appearance of two new protein bands with molecular weights of 72 and 39 KDa in C. glabrata cells treated with Zn(II) complex compared with one pure protein band 55.6 KDa in the non treated yeast cell.
Keywords: Anticandidal; Cytotoxicity; Purification; Antitumor; Metal complexes
Phenotypic, genomic and phylogenetic characteristics of rhizobia isolated from root nodules of Robinia pseudoacacia (black locust) growing in Poland and Japan by Bożena Mierzwa; Sylwia Wdowiak-Wróbel; Wanda Małek (pp. 697-710).
Rhizobial strains, rescued from the root nodules of Robinia pseudoacacia growing in Japan and Poland, were characterized for the phenotypic properties, genomic diversity as well as phylogeny and compared with the reference strains representing different species and genera of nodule bacteria. They had a moderately slow growth rate, a low tolerance to antibiotics, a moderate resistance to NaCl and produced acid in yeast mannitol agar. Cluster analysis based on the phenotypic features divided all bacteria involved in this study into four phena, comprising: (1) Rhizobium sp. + Sinorhizobium sp., (2) Bradyrhizobium sp., (3) R. pseudoacacia microsymbionts + Mesorhizobium sp., and (4) Rhizobium galegae strains at similarity coefficient of 74%. R. pseudoacacia nodule isolates and Mesorhizobium species were placed on a single branch clearly distinct from other rhizobium genera lineages. Strains representing R. pseudoacacia microsymbionts shared 98–99% 16S rDNA sequence identity with Mesorhizobium species and in 16S rDNA phylogenetic tree all these bacteria formed common cluster. The rhizobia tested are genomically heterogeneous as indicated by the AFLP (Amplified Fragment Length Polymorphism) method. The bacteria studied exhibited high degree of specificity for nodulation. Nitrogenase structural genes in these strains were located on 771–961 kb megaplasmids.
Keywords: Robinia pseudoacacia rhizobia; Taxonomy; Symbiotic plasmid
Polyphasic taxonomic studies of lactic acid bacteria associated with Tunisian fermented meat based on the heterogeneity of the 16S–23S rRNA gene intergenic spacer region by Zouhaier Ben Belgacem; Xavier Dousset; Hervé Prévost; Mohamed Manai (pp. 711-720).
The objective of this work was to investigate the structure and diversity of lactic acid bacteria (LAB) communities in traditionally fermented meat collected from different areas of Tunisia. A polyphasic study, which involves phenotypic tests and ribosomal DNA-based techniques, was used to identify Gram-positive and catalase-negative isolates. PCR amplification of the 16S–23S rDNA ISR of 102 isolates and other reference LAB strains gave (1) one type of rrn operon (M-ISR) for lactococci, (2) two types of rrn operon (S-ISR and M-ISR) for enterococci, (3) two types of rrn operon (S-ISR and L-ISR) for Lactobacilli, and (4) three PCR amplicons (S-ISR, M-ISR, and L-ISR) obtained for Pediococcus spp. and Weissella genus. The clustering and comparison of ISR–RFLP profiles given by the isolates with those given by reference LAB strains, allowed their identification as Lactococcus lactis, Enterococcus faecium, Enterococcus faecalis, Enterococcus sanguinicola, Enterococcus hawaiiensis, Lactobacillus sakei, Lactobacillus curvatus, Lactobacillus plantarum, Lactobacillus alimentarius, Pediococcus pentosaceus, and Weissella confusa. Combined 16S–23S rDNA ISR and RFLP patterns can be considered as a good potential target for a rapid and reliable differentiation between isolates of LAB and provided further information on the organization of their rrn operons.
Keywords: Lactic acid bacteria; Dry fermented meat; 16S–23S rRNA intergenic spacer region; PCR–RFLP; Specific PCR; rrn Operon
Yeast protein phosphatases Ptp2p and Msg5p are involved in G1–S transition, CLN2 transcription, and vacuole morphogenesis by Hermansyah; Minetaka Sugiyama; Yoshinobu Kaneko; Satoshi Harashima (pp. 721-733).
We previously reported that double disruption of protein phosphatase (PPase) genes PTP2 (phosphotyrosine-specific PPase) and MSG5 (phosphotyrosine and phosphothreonine/serine-PPase) causes Ca2+ sensitive growth, whereas the single disruptions do not. This finding suggests that Ptp2p and Msg5p are involved in Ca2+-induced stress response in a redundant manner. To gain insight into the molecular mechanism causing calcium sensitivity of the ∆ptp2 ∆msg5 double disruptant, we performed fluorescence-activated cell sorting analysis and found a delayed G1 phase. This delayed G1 was consistent with the defect in bud emergence, and reduced CLN2 transcription upon addition of CaCl2. We also found that Slt2p is hyper-phosphorylated in the Δptp2 Δmsg5 double disruptant and that the vacuole of the Δptp2 Δmsg5 double disruptant is fragmented even in the absence of Ca2+. These findings suggest that both Ptp2p and Msg5p are involved in the G1 to S transition and vacuole morphogenesis possibly through their regulation of Slt2 pathway.
Keywords: Saccharomyces cerevisiae ; Protein phosphatase; PTP2 ; MSG5 ; Calcium sensitivity; Delayed G1