Browsing by Author "Cunha, Joaquim"
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- Assessment of metallophytes diversity in a metal(loid) contaminated Portuguese mine for phytotechnological purposesPublication . Sousa, Ana S. S.; Pereira, Sofia I. A.; Cunha, Joaquim; Vila-Viçosa, Carlos; Castro, Paula M. L.; Moreira, Helena
- Bacterial and macro/mesofauna diversity of a Portuguese mine tailingPublication . Sousa, Ana S. S.; Pereira, Sofia I. A.; Moreira, Helena; Cunha, Joaquim; Nunes de Sousa, Álvaro; Natal-Luz, Tiago; Tentugal, Rita; Alves, Daniela; Castro, Paula M. L.
- Diversity of metallophytes and metal(loid)-tolerant bacterial strains in a portuguese mine for phytotechnologies purposesPublication . Sousa, Ana S. S.; Pereira, Sofia I. A.; Moreira, Helena; Cunha, Joaquim; Vila-Viçosa, Carlos; Castro, Paula M. L.
- Effect of bioinoculants and biochar on grapevine-associated soil microbial communitiesPublication . Pereira, Sofia I. A.; Moreira, Helena; Vega, Alberto; Cunha, Joaquim; Alves, Marta; Graça, António; Fontes, Natacha; Porto, João; Castro, Paula M. L.
- Evaluation of survival patterns and cellular injury of pseudomonas aeruginosa in different bottled waters stored under various conditionsPublication . Teixeira, Paula; Cunha, Joaquim; Albano, Helena; Ramalho, Rita; Gibbs, PaulPseudomonas aeruginosa cells were inoculated into different waters and sampled after different periods of starvation in order to evaluate the influences of storage under daylight or dark conditions, the presence or absence of the autochthonous flora, the chemical composition of the water and the storage temperature, on survival Survival was investigated by plate counts on selective and nonselective agar media. Light, low temperature (4C) and presence of the autochthonous flora negatively influenced the survival of P. aeruginosa during starvation in water. Higher survival rates were observed in waters with high mineral content. During starvation, cells developed sensitivity to the selective medium demonstrating that research is needed in the development of new media, or improvement in the existing ones, for the enumeration of P. aeruginosa in water. Current selective media/methodologies for detecting P. aeruginosa in mineral waters may seriously underestimate the levels of or presence of this organism which might represent, in some cases, a hazard to the public health.
- Fostering plant growth by the inoculation of rhizobacteria isolated from a mine tailingPublication . Sousa, Ana S. S.; Pereira, Sofia I. A.; Moreira, Helena; Darú, Flávia; Cunha, Joaquim; Castro, Paula M. L.
- Improved methods for the enumeration of heterotrophic bacteria in bottled mineral watersPublication . Ramalho, Rita; Cunha, Joaquim; Teixeira, Paula; Gibbs, Paul A.At this time the European Union regulations require that the heterotrophic plate counts (HPC) of mineral waters be assessed at two recovery temperatures: 22°C for 72 h and 37°C for 24 h. This procedure is time consuming and expensive. Development of new rapid methods for microbiological assessment of the microbial flora in the bottled water is an industry-driven need. The objectives of this work were to develop a method for the HPC that utilises only one recovery temperature and one incubation period and evaluate the use of, the LIVE/DEAD® BacLight™ Bacterial Viability Kit, 5-cyano-2,3-ditotyl tetrazolium chloride (CTC) and impedance methods to enumerate viable bacteria in bottled mineral water. Results showed that incubation at 30°C could be used instead of incubation at 22°C and 37°C. Good correlation exists between counts at 30°C and counts at 22°C (r>0.90) and all the pathogens important in mineral water analyses grow similarly at 30°C and 37°C during 24 h. It was demonstrated that impedance methods might be useful to the mineral water industry as a rapid indicator of microbiological quality of the water. Results obtained with BacLight and CTC were similar to those obtained with plate counts.
- Modified Pseudomonas agar: new differential medium for the detection/enumeration of Pseudomonas aeruginosa in mineral waterPublication . Ramalho, Rita; Cunha, Joaquim; Teixeira, Paula; Gibbs, Paul A.Pseudomonas aeruginosa has been implicated as a foodborne and waterborne pathogen and is now considered a primary infectious agent. In the present study, the survival of P. aeruginosa inoculated in mineral water was evaluated by drop counts on Pseudomonas Agar Base (PAB), PAB with CN supplement X107, PAB with cetrimide, PAB with nalidixic acid, and these media with added FeSO4. Initial counts, before starvation, were the same in all media tested. Following this period, P. aeruginosa became sensitive to PAB with added cetrimide. The addition of FeSO4 did not improve the recovery of stressed P. aeruginosa but gave colonies a typical dark brown colour being easily differentiated from other species that can grow at 42 C. The modified Pseudomonas agar medium was also tested with several P. aeruginosa strains, other species of Pseudomonas, and other genera. Only P. aeruginosa strains (pyocyanin positive) produced the typical colonies. Our results demonstrate that Pseudomonas agar with ferrous sulphate, used for the differentiation of P. aeruginosa colonies, and nalidixic acid, used as an inhibitor of Gram-positive bacteria, might be a useful medium for the detection of injured P. aeruginosa in mineral water.
- Survival characteristics of pathogens inoculated into bottled mineral waterPublication . Ramalho, Rita; Afonso, Anita; Cunha, Joaquim; Teixeira, Paula; Gibbs, Paul AnthonyTo assess the risk of contracting a waterborne disease from mineral water and to implement control systems in the mineral water industry, knowledge of the factors affecting the survival and multiplication of non-indigenous bacteria is needed. The survival of Escherichia coli, Salmonella typhimurium, Staphylococcus aureus and Yersinia enterocolitica inoculated into a Portuguese bottled mineral water was investigated under different conditions: light and dark, different recovery media, presence or absence of autochthonous flora and different ages of water, based on their culturability. For all the pathogenic bacteria higher survival was obtained under dark conditions of storage and when enumeration was performed on non-selective media. Survival of E. coli, Y. enterocolitica and S. typhimurium was longer in fresh water than in old water; results obtained with S. aureus were not conclusive. Survival of E. coli, Y. enterocolitica and S. typhimurium was lower in non-sterile mineral water while the survival of S. aureus was lower in sterilized mineral water.