Avalia??o da morfologia, virul?ncia e atividades proteol?tica e lipol?tica de isolados de Beauveria bassiana s.l. antes e ap?s reisolamento em Rhipicephalus microplus

• Autor(a) principal: Rodrigues, Caio Junior Balduino Coutinho
• Data de Publicação: 2015
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UFRRJ
• Texto Completo: https://tede.ufrrj.br/jspui/handle/jspui/2782
• topic: fungo artropodopatog?nico; carrapato dos bovinos; reisolamento; virul?ncia; atividade enzim?tica; arthropodopatogenic fungi; cattle tick; re-isolation; virulence; enzymatic activity; Medicina Veterin?ria

Beauveria bassiana sensu lato (s.l.) is a cosmopolitan fungus of great importance in agriculture. Good results are obtained when this microrganism is used as a biocontrol of Rhipicephalus microplus. In this context, studies involving the analysis of the development and fungal metabolism enable to select arthropodopatogenic isolates with better potencial. The aim of this study was to evaluate the morphology, virulence and enzymatic activities of ten B. bassiana s.l. isolates before (Micoteca group) and after reisolation (Reisolado group) through one passage (one cycle) on R. microplus. For morphology was analyzed: macromorphology, performed using the single point of inoculum; micromorphology, with cultivation between slide and cover slip and conidia production. The virulence before and after reisolation was evaluated by observing the biological parameters of R. microplus engorged females after immersion in B. bassiana s.l. aqueous suspensions (108 and 107 conidia mL-1). The proteolytic (semi-quantitative, total, Pr1 and Pr2) and lipolytic activities (?-nitrophenyl palmitate) were performed after 72 hours of fungal growth on minimal medium. The statistical analysis of the experiments was performed by comparing the data before and after reisolation for determining isolates with greater pathogenic potential and observing the effect of one passage to the potential host. Parametric data were evaluated by analysis of variance (ANOVA) followed by Tukey test and nonparametric data by Kruskal-Wallis test followed by Student-Newman-Keuls test (SNK) with 5% significance. When compared to each other before reisolation, morphological, virulence and enzymatic activities differences were observed among the isolates. CG 481 and CG 206 showed the highest control percentage (65.75% and 61.65%, respectively), although do not show the highest enzyme activity. After fungal reisolation, the process changed in small-scale the morphology and virulence. In enzymatic activity, most isolates increased the Pr2 and the lipase activities. Isolates as Bb 02 and CG 500 were those who suffered most influence after growth cycle. Bb 02 increased 1.9 times the control percentage (15.8% to 30.6%), incrementing the conidia production and making colonies that are more powdery. For this isolate was also evidenced an increase in all the enzyme activities (6.3 times to Pr1; 2.4 times to Pr2 and 9 times to lipase activity). Differently, CG 500 reduced 4.8 times the control percentage and changed the macromorphology. The enzymatic activities were also reduced by 3.6 times to Pr1; 1.2 times to Pr2 and 1.6 times to lipase activity. Therefore, the study concluded that one B. bassiana s.l. passage on R. microplus was able to change some of the isolates, although more passes by the host are necessary to provide relevant results with other isolates. Moreover, the study of enzymes such as chitinases, production of toxins and hydrophobicity of conidia should be considered to determine the fungal effectiveness.