Molecular cloning of chitinase 33 (chit33) gene from Trichoderma atroviride

In this study Trichoderma atroviride was selected as over producer of chitinase enzyme among 30 different isolates of Trichoderma sp. on the basis of chitinase specific activity. From this isolate the genomic and cDNA clones encoding chit33 have been isolated and sequenced. Comparison of genomic and cDNA sequences for defining gene structure indicates that this gene contains three short introns and also an open reading frame coding for a protein of 321 amino acids. The deduced amino acid sequence includes a 19 aa putative signal peptide. Homology between this sequence and other reported Trichoderma Chit33 proteins are discussed. The coding sequence of chit33 gene was cloned in pEt26b(+) expression vector and expressed in E. coli.

Effect of plant growth regulators on in vitro biological control of Fusarium oxysporum by Trichoderma harzianum (T8)

In this study the effect of two plant growth regulators (indolacetic acid, IAA and gibberellic acid, GA3) and also Trichoderma harzianum (T8) on the phytopathogen fungus Fusarium oxysporium (F15) was investigated. IAA and GA3 with 15 and 30 ppm concentration have no significant effect on T. harzianum (T8) growth. The biocontrol activity of T. harzianum on F. oxysporum was slightly decreased by the presence of IAA and/or GA3. Addition of 40 ppm of GA3 to the culture medium of F. oxsporum increased polygalacturonase activity about 100%. A strong increasing effect on chitinase activity (60%) by T. harzianum (T8) was observed in the presence of phytopathogenic fungus F. oxysporum, but 40 ppm IAA and/or GA3 decreased about 47% of chitinase activity of T. harzianum.

Serological and biochemical characteristics of virulence plasmid of Yersinia enterocolitica isolates from chicken in the Islamic Republic of Iran

Pathogenic Yersinia enterocolitica harbour plasmid that is essential for virulence. We studied the characteristics of virulence plasmid using serological, biochemical and bioassay tests in Y. enterocolitica isolates of chicken using plasmid curing. Plasmid-cured isogenic derivatives [2029c and 2150c] were obtained from two isolates of Y. enterocolitica [RTCC 2029 and RTCC 2150]. The results demonstrated that plasmid-bearing isolates [2029 and 2150] were human-serum-resistant when grown at 37°C, but were sensitive when grown at 25°C, whereas plasmid-cured isolates [2029c and 2150c] were sensitive when grown at both temperatures. Also autoagglutination, calcium-dependency tests and experimental infection in mice demonstrated that these phenotypes were associated with the virulence plasmid

Serological and biochemical characteristics of virulence plasmid of Yersinia enterocolitica isolates from chicken in the Islamic Republic of Iran

Pathogenic Yersinia enterocolitica harbour plasmid that is essential for virulence. We studied the characteristics of virulence plasmid using serological, biochemical and bioassay tests in Y. enterocolitica isolates of chicken using plasmid curing. Plasmid-cured isogenic derivatives (2029c and 2150c) were obtained from two isolates of Y. enterocolitica (RTCC 2029 and RTCC 2150). The results demonstrated that plasmid-bearing isolates (2029 and 2150) were human-serum-resistant when grown at 37 degrees C, but were sensitive when grown at 25 degrees C, whereas plasmid-cured isolates (2029c and 2150c) were sensitive when grown at both temperatures. Also autoagglutination, calcium-dependency tests and experimental infection in mice demonstrated that these phenotypes were associated with the virulence plasmid.