Authors:S. Naeimi, S. Khodaparast, M. Javan-Nikkhah, C. Vágvölgyi, and L. Kredics
As a first step of a project aimed at the identification of potential biocontrol agents of Rhizoctonia solani, the rice sheath blight fungus, we surveyed the biodiversity of the genus Trichoderma based on sequence of the internal transcribed spacer (ITS) 1 and 2 of the ribosomal RNA gene cluster in paddy fields in Mazandaran province, Northern Iran. Amongst the six obtained species of Trichoderma, T. harzianum and T. virens proved to be the most frequent species in this habitat. Sequence alignment and phylogenetic analysis revealed that the T. harzianum isolates can be divided into 14 different ITS genotypes clustering in four groups. Our results are in agreement with previous molecular studies, which also revealed that T. harzianum is a complex species comprising more or less different ITS genotypes. T. virens was not as diverse as T. harzianum and three different genotypes were distinguished which constituted only one cluster. All T. atroviride and T. hamatum strains had identical ITS sequences.
Authors:S. Naeimi, S. Kocsubé, Zsuzsanna Antal, S. Okhovvat, M. Javan-Nikkhah, C. Vágvölgyi, and L. Kredics
In order to identify a specific marker for T. harzianum AS12-2, a strain capable of controlling rice sheath blight caused by Rhizoctonia solani, UP-PCR was performed using five universal primers (UP) both separately and in pairwise combinations. The application of two UP primers resulted in the amplification of unique fragments from the genomic DNA of T. harzianum AS12-2, clearly distinguishing it from other Trichoderma strains. The unique fragments had no significant sequence homology with any other known sequence available in databases. Based on the sequences of the unique fragments, 14 oligonucleotide primers were designed. Two primer sets amplified a fragment of expected size from the DNA of strain T. harzianum AS12-2 but not from any other examined strains belonging to T. harzianum, to other Trichoderma species assayed, or to other common fungi present in paddy fields of Mazandaran province, Iran. In conclusion, SCAR (sequence characterized amplified regions) markers were successfully identified and rapid, reliable tools were provided for the detection of an effective biocontrol Trichoderma strain, which can facilitate studies of its population dynamics and establishment after release into the natural environment.
Authors:Miklós Takó, Alexandra Kotogán, Judit Krisch, Csaba Vágvölgyi, Keshab C. Mondal, and Tamás Papp
Cellulolytic, lipolytic and proteolytic enzyme production of zygomycetes Mucor corticolus, Rhizomucor miehei, Gilbertella persicaria and Rhizopus niveus were investigated using agro-industrial wastes as substrates. Solid-state cultures were carried out on untreated corn residues (stalk and leaf) as single substrate (SSF1) or corn residues and wheat bran in mixed fermentation (SSF2). Rapid production of endoglucanase (CMCase) was observed with maximal activity reaching after about 48-h fermentation, while cellobiohydrolase (CBH) and β-glucosidase enzymes generally had their peak after 72-h incubation. Highest filter paper degrading (FPase), CMCase, CBH and β-glucosidase activities obtained were (U g−1 dss) 17.3, 74.1, 12.2 and 158.3, for R. miehei, G. persicaria, M. corticolus and Rh. niveus, respectively. M. corticolus proved to be the best lipolytic enzyme producer in SSF1 presenting 447.6 U g−1 dss yield, while R. miehei showed 517.7 U g−1 dss activity in SSF2. Rh. niveus exhibited significantly greater protease production than the other strains. Suc-AAPF-pNA hydrolyzing activities of this strain were 1.1 and 1.96 U g−1 dss in SSF1 and SSF2, respectively. We conclude that the used corn stalk and leaf residues could potentially be applicable as strong inducers for cellulase and lipase production by Mucoromycotina fungi.
Authors:Zsuzsanna Antal, L. Kredics, J. Pakarinen, Ilona Dóczi, Maria Andersson, Mirja Salkinoja-Salonen, L. Manczinger, A. Szekeres, L. Hatvani, C. Vágvölgyi, and Elisabeth Nagy
Potential virulence factors of 9 saprophytic and 12 clinical Trichoderma longibrachiatum strains were examined in the present study, in order to compare their capacity to cause infection in humans. All of the strains were able to grow at temperatures up to 40 °C and at pH values ranging from 2.0 to 9.0. Carbon and nitrogen source utilization experiments revealed that all of the strains were able to utilize a series of basic amino acids both as sole carbon and nitrogen sources. The MIC values of the tested antifungal drugs were found to be 0.016-8 µg/ml for amphotericin B, 64-256 µg/ml for fluconazole, 0.5-32 µg/ml for itraconazole and 0.008-1 µg/ml for ketoconazole in the case of the examinedis olates. Metabolites of the strains inhibited the growth of different bacteria, furthermore, compounds produced by three clinical isolates reduced the motility of boar spermatozoa, indicating their toxicity to mammalian cells as well. On the whole, there were no significant differences in the examined features between strains derived from clinical or soil samples. The question, however, whether all environmental Trichoderma longibrachiatum strains have the capacity to cause infections or not, remains still unanswered.