The lipase from Rhizomucor miehei (RML) has been immobilized on chitosan-based hybrid (sodium alginate or carrageenan) matrices activated with glycidol (GLY), epichlorohydrin (EPI) or glutaraldehyde (GLU) groups. Then, the properties of the different biocatalysts have been evaluated and compared with the soluble RML. Thermal stability (at pH 7.0 and 60 °C) was significantly increased when compared to the soluble enzyme: 154-fold for chitosan 5.0% - GLU, 80-fold for chitosan 2.5% - carrageenan 2.5% - GLY and 93-fold for chitosan 2.5% - alginate 2.5% - EPI. The best biocatalyst preparation, which was 154-fold more stable than the soluble enzyme, was obtained when RML was immobilized on chitosan activated with glutaraldehyde 5.0% v/v. According to the results, it was concluded that RML immobilization on chitosan-based hybrid matrices using different chemistries greatly produced biocatalysts with different properties.

A pesquisa de formulações com agentes biológicos exige estudos com diferentes veículos de aplicação para a seleção dos que permitam a sobrevivência, estabilidade e uma boa distribuição do agente antagônico na superfície a ser tratada. A eficiência de duas leveduras killer, Wickerhamomyces anomalus (cepa 422) e Meyerozyma guilliermondii (cepa 443), associadas com cinco diferentes veículos de aplicação, foi avaliada quanto à proteção do mamão na pós-colheita. Neste trabalho, com 90 dias de incubação a 4 ºC, W. anomalus (cepa 422) e M. guilliermondii (cepa 443) mantiveram-se viáveis em todos os veículos de aplicação testados. Frutos tratados com diferentes formulações (leveduras + veículos de aplicação) tiveram menor incidência de doença (pelo menos 30%) quando comparados a frutos não tratados. No tratamento com W. anomalus (cepa 422) + amido 2% a doença foi 48,3% menor. Nos tratamentos que empregaram a M. guilliermondii (cepa 443), os mais eficientes foram aqueles que utilizaram a gelatina 2% e a cera líquida de carnaúba 2%; ambos reduziram em 50% a antracnose pós-colheita dos mamões. Eletromicrografias do tecido da superfície dos frutos tratados revelaram que todos os veículos de aplicação proporcionaram excelente adesão das leveduras à superfície. As formulações baseadas em amido de milho (2%), gelatina (2%) e cera-de-carnaúba (2%) foram as mais eficientes no controle de doenças fúngicas em pós-colheita de mamão.

To identify formulations of biological agents that enable survival, stability and a good surface distribution of the antagonistic agent, studies that test different application vehicles are necessary. The efficiency of two killer yeasts, Wickerhamomyces anomalus (strain 422) and Meyerozyma guilliermondii (strain 443), associated with five different application vehicles, was assessed for the protection of postharvest papayas. In this study, after 90 days of incubation at 4ºC, W. anomalus (strain 422) and M. guilliermondii (strain 443) were viable with all application vehicles tested. Fruits treated with different formulations (yeasts + application vehicles) had a decreased severity of disease (by at least 30%) compared with untreated fruits. The treatment with W. anomalus (strain 422) + 2% starch lowered disease occurrence by 48.3%. The most efficient treatments using M. guilliermondii (strain 443) were those with 2% gelatin or 2% liquid carnauba wax, both of which reduced anthracnose by 50% in postharvest papayas. Electron micrographs of the surface tissues of the treated fruits showed that all application vehicles provided excellent adhesion of the yeast to the surface. Formulations based on starch (2%), gelatin (2%) and carnauba wax (2%) were the most efficient at controlling fungal diseases in postharvest papayas.

Glycerol, a co-product of the biodiesel industry, may be a suitable raw material for the production of high added-value compounds by the microorganisms. This study aimed to use the glycerol obtained from the biodiesel production process as the main carbon source for biosurfactant production by Bacillus subtilis ATCC 6633. Results indicated that the strain lowered the surface tension of the cell-free fermented broth to 31.5 ± 1.6 mN/m, indicating the production of biosurfactant. The critical micelle concentration (CMC = 33.6 mN/m) obtained was similar to the previously reported for biossurfactants isolated from other Bacillus. The produced biosurfactant was able to emulsify n-hexadecane and soybean oil.