ENZYMATIC AND GENETIC VARIABILITY IN Bacillus spp. STRAINS WITH PLANT BENEFICIAL QUALITIES

摘要

Plant health is one of the issues that have to be maintained and closely monitored during cultivation and harvest. In this regard, prevention is the key factor in organic production. Biological control of plant pathogens and plant growth stimulation can be done through beneficial microorganisms. Different bacterial bio-preparates are available on the market, many of them based on selected strains of Bacillus species. In our previous studies, we isolated autochthones strains of Bacillus spp. with beneficial traits for plant protection and growth promotion. Considering the interest for biological production, and public concern for healthy products without significantly reduced yield, different biological control strains of Bacillus spp. that could be used as bio-inoculants for plant protection were analyzed. Thirteen biocontrol strains of Bacillus spp. were analyzed in comparison with three referent strains of B.subtilis and B.licheniformis. Qualitative and semi-quantitative analysis of these biocontrol Bacillus spp. strains was studied in order to characterize their enzymatic activity with implications either in cell wall degradation of plant pathogenic microorganisms, or in metabolism of various substrates. Genetic variability was studied by rep-PCR analysis compared with reference strains of B.subtilis and B.licheniformis. Microbiological studies performed in order to characterize the selected beneficial bacteria for their ability to produce lytic enzyme involved in plant pathogenic inhibition and plant growth stimulation revealed chitinase, cellulose, protease, lipase, amylase, decarboxylase, ACC-deaminase and phosphatase activity. The molecular techniques revealed significant genetic differences among the bacterial strains analyzed. The study allowed the detection of several enzymatic mechanisms involved in plant growth and protection, and revealed the potential of autochthon microbiota to be used for biotechnological purposes.