Browsing by Author "Nunes, Olga"
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- Characterization of bacterial communities from Masseiras, a unique Portuguese greenhouse agricultural systemPublication . Becerra-Castro, Cristina; Lopes, Ana Rita; Teixeira, Sara; Silva, M. Elisabete F.; Pimenta, Elisabete; Manaia, Célia M.; Nunes, Olga‘‘Masseiras’’ is an ancient Portuguese agriculture system, where soil was developed from sand dunes enriched with seaweeds over more than a century. Due to the importance for the local economy, this system evolved for greenhouse structures. In this study we compared the bacterial community composition and structure of ‘‘Masseiras’’ soil, aiming at assessing the potential impact of different agricultural practices. The bulk soil of two greenhouses (following or not the recommended agriculture good practices, FGP and NFGP, respectively) was compared based on their physicochemical properties and bacterial community. In both FGP and NFGP, Proteobacteria, Acidobacteria, Actinobacteria, Bacteroidetes, Firmicutes, and Gemmatimonadetes were in a proportion of 5:1:1:1:1:1. However, the bacterial community of soil FGP was richer and more diverse than that of soil NFGP. Members of the classes Bacilli and Gemm-1, with higher relative abundance in NFGP and FGP, respectively, were those contributing most for distinguishing the bacterial communities of both soils. The differences in the structure of the bacterial communities correlated (Mantel test) with some soil physicochemical properties, such as electrical conductivity and nitrate and Zn contents, which were significantly higher in soil NFGP than in soil FGP.
- Comparison of the bacterial composition of two commercial composts with different physicochemical, stability and maturity propertiesPublication . Silva, Elisabete; Lopes, Ana; Cunha-Queda, Ana; Nunes, OlgaPreviously, two municipal solid waste commercial composts (MSW1 and MSW2) were characterized. Although sharing the same type of raw material, most of their physicochemical, stability and maturity properties differed. The present study aimed to characterize them at a microbiological level, and to infer on possible relationships between the composts properties and the structure of their bacterial communities. Both the 16S rRNA gene-based PCR-DGGE profiling and 454-pyrosequencing technology showed that the structure of the bacterial communities of these composts was distinct. The bacterial community of MSW1 was more diverse than that of MSW2. Multivariate analyses revealed that the high electrical conductivity, Cu content as well as the low phytotoxity of compost MSW1, when compared to MSW2, contributed most to shape its bacterial community structure. Indeed, high abundance of halophilic (Halomonadaceae and Brevibacteriaceae) and metal resistant organisms (Brevibacteriaceae and Bacillaceae) were found in MSW1. In addition, Pseudonocardiaceae, Streptomycetaceae, Bacillaceae, and Brevibacteriaceae may have contributed to the high humic-like acids content and low phytotoxicity of MSW1. In contrast, the high organic matter content and the high density of the cultivable fungi population were the parameters most correlated with the structure of the bacterial community of compost MSW2, dominated by Corynebacteriaceae and mainly Aerococcaceae, taxonomic groups not commonly found in composts.
- Irrigation with Treated Wastewater: Potential Impacts on Microbial Function and Diversity in Agricultural SoilsPublication . Lopes, Ana Rita; Becerra-Castro, Cristina; Vaz-Moreira, Ivone; Silva, Elisabete; Nunes, Olga; Manaia, CéliaThe reuse of treated wastewater could be a promising measure to attenuate the water scarcity burden. In agriculture, irrigation with wastewater may contribute to improve production yields, reduce the ecological footprint and promote socioeconomic benefits. However, it cannot be considered exempt of adverse consequences in environmental and human health. Apart from the introduction of some biological and chemical hazardous agents, the disturbance of the indigenous soil microbial communities and, thus, of vital soil functions impacting soil fertility may occur. The consequences of these disturbances are still poorly understood. This chapter summarises the physicochemical and microbiological alterations in soil resultant from irrigation with treated wastewater that are described in scientific literature. These alterations, which involve a high complexity of variables (soil, wastewater, climate, vegetal cover), may have impacts on soil quality and productivity. In addition, possible health risks may arise, in particular through the direct or indirect contamination of the food chain with micropollutants, pathogens or antibiotic resistance determinants. The current state of the art suggests that irrigation with treated wastewater may have a multitude of long-term implications on soil productivity and public health. Although further research is needed, it seems evident that the analysis of risks associated with irrigation with treated wastewater must take into account not only the quality of water, but other aspects as diverse as soil microbiota, soil type or the cultivated plant species.
- Wastewater reuse in irrigation: A microbiological perspective on implications in soil fertility and human and environmental healthPublication . Becerra-Castro, Cristina; Lopes, Ana Rita; Vaz-Moreira, Ivone; Silva, Elisabete; Manaia, Célia; Nunes, OlgaThe reuse of treated wastewater, in particular for irrigation, is an increasingly common practice, encouraged by governments and of fi cial entities worldwide. Irrigation with wastewater may have implications at two different levels:alterthephysicochemicalandmicrobiologicalpropertiesofthesoiland/orintroduceandcontributetothe accumulation of chemical and biological contaminants in soil. The fi rst may affect soil productivity and fertility; the second may pose serious risks to the human and environmental health. The sustainable wastewater reuse in agriculture should prevent both typesofeffects,requiring a holisticand integratedrisk assessment. Inthis article wecriticallyreviewpossible effects of irrigation with treatedwastewater, with special emphasison soil microbi- ota. The maintenance of a rich and diversi fi ed autochthonous soil microbiota and the use of treated wastewater with minimal levels of potential soil contaminants are proposed as sine qua non conditions to achieve a sustain- able wastewater reuse for irrigation.