RESUMO
The efficacy of the fungus Metarhizium rileyi (Farlow) Kepler, S. A. Rehner & Humber (Hypocreales: Clavicipitaceae) against the fall armyworm Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) and the impact on the community of epigeans predators as well as the natural occurrence of native fungal strains were evaluated after sequential sprays in maize. In the first season, the infestation was lower than 0.2 larvae per plant throughout the three fungal sprays and no significant difference was observed in the number of infected larvae among treatments. In the second season, insect population reached an average of 0.8 larvae per plant between the second and third sprays and the number of larvae succumbed by M. rileyi was higher in fungal-treated plots in the following weeks. Molecular characterization of the collected isolates on mummified larvae revealed the introduction of a new isolate did not eliminate the native strain on the fungal-treated plots. In both seasons, the diversity and abundance of predator species in the plots were not affected by any of the treatments. We showed that applications of selected strains of M. rileyi early in the season have no significant impact on the occurrence of natural enemies in maize.
Assuntos
Metarhizium , Mariposas , Animais , Larva , Spodoptera , Zea maysRESUMO
Yakupa is a traditional non-alcoholic cassava beverage produced by Brazilian Amerindians. In this work the microbial dynamics and metabolites involved in yakupa fermentation were investigated by PCR-denaturing gradient gel electrophoresis and chromatography analysis, respectively. The lactic acid bacteria (LAB) population was higher than yeast in the beginning of fermentation (5 log CFU mL(-1) and 3 log CFU mL(-1), respectively) and after 36 h both population increased reaching 7 log CFU mL(-1), remaining constant until 60 h. Culture dependent and independent methods in combination identified the bacteria Lactobacillus fermentum, L. plantarum, Weissela cibaria and W. confusa, and yeasts Saccharomyces cerevisiae and Pichia kudriavzevii. Maltose (41.2 g L(-1)), ethanol (6.5 g L(-1)) and lactic acid (7.8 g L(-1)) were the most abundant compounds identified by high performance liquid chromatography. Aldehydes, acids, alcohols and esters were identified by gas chromatography flame ionization detection. By the metabolites and PCA analysis we may assign the beverage's flavor to the microbial metabolism. Heterolactic LAB and S. cerevisiae dominated the yakupa fermentation, being responsible for the organoleptic characteristics of the final product. This is the first time that the microbial dynamics and physicochemical parameters were investigated in the yakupa beverage and it may contribute to the future selection of starter cultures to perform yakupa fermentations.
Assuntos
Bebidas/microbiologia , Biota , Fenômenos Químicos , Carga Bacteriana , Brasil , Cromatografia , Cromatografia Gasosa , Contagem de Colônia Microbiana , Eletroforese em Gel de Gradiente Desnaturante , Etanol/análise , Fermentação , Fungos/isolamento & purificação , Ácido Láctico/análise , Lactobacillales/isolamento & purificação , Maltose/análise , Manihot/metabolismo , Fatores de TempoRESUMO
Spontaneous cocoa bean fermentations carried out in a novel-design 40-kg-capacity stainless steel tank (SST) was studied in parallel to traditional Brazilian methods of fermentation in wooden boxes (40-kg-capacity wooden boxes (WB1) and 600-kg-capacity wooden boxes (WB2)) using a multiphasic approach that entailed culture-dependent and -independent microbiological analyses of fermenting cocoa bean pulp samples and target metabolite analyses of both cocoa pulp and cotyledons. Both microbiological approaches revealed that the dominant species of major physiological roles were the same for fermentations in SST, relative to boxes. These species consisted of Saccharomyces cerevisiae and Hanseniaspora sp. in the yeast group; Lactobacillus fermentum and L. plantarum in the lactic acid bacteria (LAB) group; Acetobacter tropicalis belonging to the acetic acid bacteria (AAB) group; and Bacillus subtilis in the Bacillaceae family. A greater diversity of bacteria and non-Saccharomyces yeasts was observed in box fermentations. Additionally, a potentially novel AAB belonging to the genus Asaia was isolated during fermentation in WB1. Cluster analysis of the rRNA genes-PCR-DGGE profiles revealed a more complex picture of the box samples, indicating that bacterial and yeast ecology were fermentation-specific processes (wooden boxes vs. SST). The profile of carbohydrate consumption and fermentation products in the pulp and beans showed similar trends during both fermentation processes. However, the yeast-AAB-mediated conversion of carbohydrates into ethanol, and subsequent conversion of ethanol into acetic acid, was achieved with greater efficiency in SST, while temperatures were generally higher during fermentation in wooden boxes. With further refinements, the SST model may be useful in designing novel bioreactors for the optimisation of cocoa fermentation with starter cultures.
Assuntos
Bactérias/metabolismo , Reatores Biológicos/normas , Cacau , Fermentação , Microbiologia de Alimentos/instrumentação , Aço Inoxidável , Leveduras/metabolismo , Bactérias/genética , Bactérias/isolamento & purificação , Biodiversidade , Brasil , Cacau/metabolismo , Cacau/microbiologia , Metabolismo dos Carboidratos , Análise por Conglomerados , Microbiologia de Alimentos/normas , Genes de RNAr/genética , Leveduras/genéticaRESUMO
Microorganisms associated with the fermentation of cotton seed and rice were studied using a combination of culture-dependent and -independent methods. Samples of the cotton seed and rice beverage were collected every 8 h during the fermentation process for analysis of the microbiota present over 48 h. The lactic acid bacteria (LAB) population reached values of approximately 8.0 log cfu/mL. A total of 162 bacteria and 81 yeast isolates were identified using polyphasic methods. LAB (Lactobacillus plantarum, Lactobacillus vermiforme, Lactobacillus paracasei) were the most frequently isolated bacteria. Bacillus subtilis was present from 16 h until the end of the fermentation process. A decrease in pH value from 6.92 (0 h) to 4.76 (48 h) was observed, and the concentration of lactic acid reached 24 g/L at the end of the fermentation process. DGGE (denaturing gradient gel electrophoresis) was performed to determine the dynamics of the communities of bacteria and yeast, and the analysis revealed a predominance of LAB throughout the fermentation process. No changes were observed in the yeast community. The yeast species detected were Candida parapsilosis, Candida orthopsilosis, Clavispora lusitaniae and Rhodotorula mucilaginosa. Our studies indicate that the DGGE technique combined with a culture-dependent method is required to discern the dynamics in the fermentation of cotton seed and rice.
Assuntos
Bebidas/microbiologia , Fermentação , Gossypium/microbiologia , Lactobacillus/isolamento & purificação , Oryza/microbiologia , Leveduras/isolamento & purificação , Brasil , Eletroforese em Gel de Gradiente Desnaturante , Humanos , Indígenas Sul-Americanos , Sementes/microbiologiaRESUMO
Cauim is a fermented beverages prepared by Tapirapé Amerindians in Brazil from substrates such as cassava, rice, peanuts, pumpkin, cotton seed and maize. Here we study the microorganisms associated with peanut and rice fermentation using a combination of culture-dependent and -independent methods. The bacterial population varied from 7.4 to 8.4 log CFU/ml. The yeast population varied from 4.0 to 6.6 log CFU/ml. A total of 297 bacteria and yeasts strains were isolated during fermentation, with 198 bacteria and 99 yeast. The Lactobacillus genus was dominant throughout fermentation. Bacteria and yeast community dynamics during the fermentation process were monitored by PCR-DGGE analysis. Both culture-dependent and -independent methods indicated that the bacterial species L. plantarum, L. fermentum, L. paracasei and L. brevis as well as the yeast species P. guilliermondii, K. lactis, Candida sp, R. toruloides and Saccharomyces cerevisiae, were dominant during fermentation. Multivariate analysis of microorganisms during beverage fermentation showed that the microbial community changed during the fermentation process.