Effects of substratum on the diversity and stability of ammonia-oxidising communities in a constructed wetland used for wastewater treatment

Aim: To study the relationship between the nature of the substratum and the diversity and stability of the ammonia-oxidizing microbial community in a constructed wetland for the treatment of wastewaters. Methods and Results: Samples have been taken the year around from sections of the wetland filled with different substrata. When present, the root zones of the helophyte Phragmites australis were also sampled. The diversity of the ammonia-oxidizing community was established by a coupled PCR–DGGE method based on the 16s rRNA gene. Averaged over the seasons, no large differences in community composition were observed between the different substrata, although the section with zeolite always showed t Conclusions: Although the ammonia-oxidizing communities did not differ significantly between the different sections of the constructed wetland, the characteristics of zeolite were most appropriate to accommodate a stable and active community of ammonia-oxidizing bacteria. The presence of the helophyte had no effect on the diversity and stability of the ammonia-oxidizing community. Significance and Impact of the Study: It has been shown that substrata used in constructed wetlands made no distinction between ammonia-oxidizing strains in relation to attachment. However, zeolite had the best performance with respect to activity over the season

Identification of spore-forming strains involved in biodegradation of acifluorfen

We isolated and identified four spore-forming bacteria from activated sludges and soil, three of which were able to degrade acifluorfen. Biochemical characteristics, DNA base composition and DNA-DNA homology indicated that the degrading strains belonged to the species Bacillus thuringiensis, Clostridium perfringens and Clostridium sphenoides. The fourth strain, identified as C. sphenoides and showing the same characteristics of the corresponding degrading strain, was unable to metabolize acifluorfen. Thus, the plasmid content of these strains was analysed to study the possible correlation between the presence of extrachromosomal elements and the ability to degrade this herbicide

Effects of substratum on the diversity and stability of ammonia-oxidising communities in a constructed wetland used for wastewater treatment

Aim: To study the relationship between the nature of the substratum and the diversity and stability of the ammonia-oxidizing microbial community in a constructed wetland for the treatment of wastewaters. Methods and Results: Samples have been taken the year around from sections of the wetland filled with different substrata. When present, the root zones of the helophyte Phragmites australis were also sampled. The diversity of the ammonia-oxidizing community was established by a coupled PCR–DGGE method based on the 16s rRNA gene. Averaged over the seasons, no large differences in community composition were observed between the different substrata, although the section with zeolite always showed t Conclusions: Although the ammonia-oxidizing communities did not differ significantly between the different sections of the constructed wetland, the characteristics of zeolite were most appropriate to accommodate a stable and active community of ammonia-oxidizing bacteria. The presence of the helophyte had no effect on the diversity and stability of the ammonia-oxidizing community. Significance and Impact of the Study: It has been shown that substrata used in constructed wetlands made no distinction between ammonia-oxidizing strains in relation to attachment. However, zeolite had the best performance with respect to activity over the seasons

Efeito de linhagens de Fusarium oxysporum antagonistas em grupos funcionais de bactérias do solo.

Linhagens de Fusarium oxysporum antagonistas estão sendo utilizadas na Itália para o controle biológico de Fusarium spp., em diversas culturas, especialmente em condições de estufa. O presente trabalho teve como objetivo conhecer as interações entre as linhagens antagonistas, geneticamente manipuladas ou não, e grupos funcionais de bactérias do solo, envolvidas no ciclo do carbono e do nitrogênio. Foram avaliados três solos agrícolas da região de Albenga (norte da Italia), sendo dois solarizados e o outro não, e um solo cultivado com Popolus por dez anos da região de Carignano (norte da Itália). Não foram observadas diferenças significativas, após a introdução dos antagonistas, quando foram avaliados os efeitos nos grupos funcionais: amonificadores, oxidadores de nitrito e amônia, fixadores não simbiontes aeróbicos e anaeróbicos de nitrogênio e denitrificadores, pelo método do número mais provável. Também não foram observados efeitos em bactérias amilolíticas, proteolíticas, celulolíticas, pectinolíticas e bactérias totais, através do método de contagem de colônias em meio de cultura seletivo.Made available in DSpace on 2016-11-22T23:00:24Z (GMT). No. of bitstreams: 1 1996AP009GhiniEfeito3166.pdf: 19458 bytes, checksum: fe2f32e3b0bf9d08f692ca883939dbc1 (MD5) Previous issue date: 1996-10-09199

Quality of minimally processed red chicory (Cichorium intybus L.) evaluated by anthocyanin content, radical scavenging activity, sensory descriptors and microbial indices

Changes in the quality of minimally processed red chicory (Cichorium intybus L.) were studied during storage in a polyvinyl chloride (PVC) film and in a mono-oriented polypropylene (OPP) film at 4 °C. The maximum limit for mesophilic aerobic bacterial count was attained after 4 days using the PVC film and after 4.5 days using the OPP film. The loss of fruity aroma occurred after 3 days in the products stored in PVC but not in those stored in OPP. In spite of microbial growth, no off-odour was perceived by trained panellists. Storage in PVC slightly decreased the contents of cyanidin 3-O-malonyl glucoside, total phenolics and antioxidant activity, whereas these parameters increased upon storage in OPP. When red chicory heads subjected to mild stress in the field were minimally processed, OPP packaging decreased the microbial growth with respect to PVC, but antioxidants were degraded in both conditions

Efeito de linhagens de Fusarium oxysporum antagonistas em grupos funcionais de bactérias do solo.

Linhagens de Fusarium oxysporum antagonistas estão sendo utilizadas na Itália para o controle biológico de Fusarium spp., em diversas culturas, especialmente em condições de estufa. O presente trabalho teve como objetivo conhecer as interações entre as linhagens antagonistas, geneticamente manipuladas ou não, e grupos funcionais de bactérias do solo, envolvidas no ciclo do carbono e do nitrogênio. Foram avaliados três solos agrícolas da região de Albenga (norte da Italia), sendo dois solarizados e o outro não, e um solo cultivado com Popolus por dez anos da região de Carignano (norte da Itália). Não foram observadas diferenças significativas, após a introdução dos antagonistas, quando foram avaliados os efeitos nos grupos funcionais: amonificadores, oxidadores de nitrito e amônia, fixadores não simbiontes aeróbicos e anaeróbicos de nitrogênio e denitrificadores, pelo método do número mais provável. Também não foram observados efeitos em bactérias amilolíticas, proteolíticas, celulolíticas, pectinolíticas e bactérias totais, através do método de contagem de colônias em meio de cultura seletivo

Physicochemical, microbial, and sensory parameters as indices to evaluate the quality of minimally-processed carrots

The quality of minimally-processed carrots was studied during storage at 4 and 10 \u25e6C by evaluating: (a) the physicochemical indices, namely: chlorogenic acid, carotenoids, sugars, and whiteness index (WI); (b) the microbial indices, namely: total bacterial count (TBC), coliforms, lactic acid bacteria, yeasts; (c) the sensory attributes, namely: fruity aroma, color (whitening), and off-odor. The kinetics of quality indices variation was determined, and the relationships between sensory perception of undesired changes, microbial contamination thresholds, carotenoid degradation, and physicochemical indices were investigated in order to select the most significant parameters to be controlled for evaluating carrot stability during storage. Results showed that chlorogenic acid concentration and WI increased following a pseudo-first order and a zero-order kinetics, respectively. Microbial population growth, fitted with the Gompertz model, showed that TBC and total coliforms reached the threshold concentration in a shorter time than other microbial groups (7 days at 4 \u25e6C and 3 days at 10 \u25e6C, respectively). Although the above described changes indicate that carrots underwent degradation, no carotenoid loss was observed during storage at 4 and 10 \u25e6C. Whitening and decrease in fruity aroma were perceived by a trained sensory panel of assessors after 5 days of storage at 4 \u25e6C (prior to the maximum acceptable microbial contamination), whereas off-odorwas perceived 2 days later, when carrots attained the microbial contamination threshold. WI was correlated to the visual appearance of whitening and to the perception of off-odor. No correlation was found between the other physicochemical and microbial parameters and sensory attributes. Based on these results, WI was the most sensitive indicator of sensory quality of processed carrot sticks, and TBC together with total coliforms allowed the evaluation of their microbial quality