RESUMO
An important pollutant produced during the cheese making process is cheese whey which is a liquid by-product with high content of organic matter, composed mainly by lactose and proteins. Hydrogen can be produced from cheese whey by dark fermentation but, organic matter is not completely removed producing an effluent rich in volatile fatty acids. Here we demonstrate that this effluent can be further used to produce energy in microbial fuel cells. Moreover, current production was not feasible when using raw cheese whey directly to feed the microbial fuel cell. A maximal power density of 439 mW/m2 was obtained from the reactor effluent which was 1000 times more than when using raw cheese whey as substrate. 16S rRNA gene amplicon sequencing showed that potential electroactive populations (Geobacter, Pseudomonas and Thauera) were enriched on anodes of MFCs fed with reactor effluent while fermentative populations (Clostridium and Lactobacillus) were predominant on the MFC anode fed directly with raw cheese whey. This result was further demonstrated using culture techniques. A total of 45 strains were isolated belonging to 10 different genera including known electrogenic populations like Geobacter (in MFC with reactor effluent) and known fermentative populations like Lactobacillus (in MFC with cheese whey). Our results show that microbial fuel cells are an attractive technology to gain extra energy from cheese whey as a second stage process during raw cheese whey treatment by dark fermentation process.
Assuntos
Queijo , Fontes de Energia Bioelétrica , RNA Ribossômico 16S , Soro do Leite , Proteínas do Soro do LeiteRESUMO
Fusarium proliferatum is an important pathogen that is associated with plant diseases and primarily affects aerial plant parts by producing different mycotoxins, which are toxic to humans and animals. Within the last decade, this fungus has also been described as one of the causes of red root rot or sudden death syndrome in soybean, which causes extensive damage to this crop. This study describes the Agrobacterium tumefaciens-mediated transformation of F. proliferatum as a tool for the disruption of pathogenicity genes. The genetic transformation was performed using two binary vectors (pCAMDsRed and pFAT-GFP) containing the hph (hygromycin B resistance) gene as a selection marker and red and green fluorescence, respectively. The presence of acetosyringone and the use of filter paper or nitrocellulose membrane were evaluated for their effect on the transformation efficiency. A mean processing rate of 94% was obtained with 96 h of co-cultivation only in the presence of acetosyringone and the use of filter paper or nitrocellulose membrane did not affect the transformation process. Hygromycin B resistance and the presence of the hph gene were confirmed by PCR, and fluorescence due to the expression of GFP and DsRed protein was monitored in the transformants. A high rate of mitotic stability (95%) was observed. The efficiency of Agrobacterium-mediated transformation of F. proliferatum allows the technique to be used for random insertional mutagenesis studies and to analyze fungal genes involved in the infection process.
Assuntos
Fusarium/genética , Glycine max/genética , Doenças das Plantas/microbiologia , Transformação Genética , Agrobacterium/genética , Resistência à Doença/genética , Fusarium/patogenicidade , Vetores Genéticos , Proteínas de Fluorescência Verde/genética , Higromicina B/toxicidade , Componentes Aéreos da Planta/microbiologia , Doenças das Plantas/genética , Glycine max/microbiologiaRESUMO
Luehea divaricata is an important plant in popular medicine; it is used for its depurative, anti-inflammatory, and other therapeutic activities. We evaluated the antimicrobial activity of endophytic fungi isolated from leaves of L. divaricata against phytopathogens and pathogenic bacteria, and characterized the isolates based on amplified ribosomal DNA restriction analysis (ARDRA). The in vitro antagonistic activity of these endophytes against the phytopathogen Alternaria alternata was assayed by dual culture technique. Based on this evaluation of antimicrobial activity, we extracted secondary metabolites from nine endophytic fungi by partitioning in ethyl acetate and methanol. These were tested against the phytopathogens A. alternata, Colletotrichum sp and Moniliophthora perniciosa, and against the human pathogenic bacteria Escherichia coli and Staphylococcus aureus. Molecular characterization by ARDRA technique was used for phylogenetic analysis, based on comparison with sequences in GenBank. The endophytes had varied effects on A. alternata. One isolate produced an inhibition halo against M. perniciosa and against E. coli. This antibiosis activity indicates a role in the protection of the plant against microbial pathogens in nature, with potential for pharmaceutical and agricultural applications. Based on ARDRA, the 13 isolates were grouped. We found three different haplotypes of Phomopsis sp, showing interspecific variability. It appears that examination of the microbial community associated with medicinal plants of tropical regions has potential as a useful strategy to look for species with biotechnological applications.
Assuntos
Antibiose , Bactérias/genética , DNA Ribossômico/genética , Endófitos , Fungos/genética , Interações Hospedeiro-Patógeno , Malvaceae/microbiologia , Bactérias/classificação , Técnicas de Cocultura , Fungos/classificação , Variação Genética , Filogenia , Metabolismo SecundárioRESUMO
This study investigated the microbial community developed in a UASB reactor for hydrogen production and correlated it to reactor performance. The reactor was inoculated with kitchen waste compost and fed with raw cheese whey at two organic loading rates, 20 gCOD/Ld and 30 gCOD/Ld. Hydrogen production was very variable, using an OLR of 30 gCOD/Ld averaged 1.0 LH(2)/Ld with no methane produced under these conditions. The hydrogen yield was also very variable and far from the theoretical. This low yield could be explained by selection of a mixed fermentative population with presence of hydrogen producing organisms (Clostridium, Ruminococcus and Enterobacter) and other non-hydrogen producing fermenters (Lactobacillus, Dialister and Prevotella). The molecular analysis of the raw cheese whey used for feeding revealed the presence of three predominant organisms that are affiliated with the genera Buttiauxella (a low-yield hydrogen producer) and Streptococcus (a lactic acid-producing fermenter). Although these organisms did not persist in the reactor, the continuous addition of these fermenters could decrease the reactor's hydrogen yield.
Assuntos
Bactérias/classificação , Bactérias/metabolismo , Reatores Biológicos , Hidrogênio/metabolismo , Proteínas do Leite/metabolismo , Anaerobiose , Biomassa , Fermentação , Indústria Alimentícia , Resíduos Industriais , Proteínas do Leite/química , Eliminação de Resíduos Líquidos , Proteínas do Soro do LeiteRESUMO
A sample of 1,752 bovine sera collected from 99 herds throughout the Tenth Region, Chile, from March 8 to November 20, 1982, was analyzed for bluetongue (BT) antibodies using the immunodiffusion (ID) test. The prevalence of BT virus (BTV) antibody was 19.6%. Sixty-four (64.6%) herds showed at least 1 positive animal, which suggests an important antibody distribution in the area. The examination of 500 sera of sheep in 14 herds indicated the following results: 8/500 animals were positive in 5/14 of the herds.