Abstract
ABSTRACT Irrigation water and cultivated soil have been identified as possible sources of contamination in several crops. In certain vegetables that are eaten raw, such as lettuce, this contamination can lead to public health problems. Aiming to evaluate the influence of these sources on the quality of lettuce grown in the Córrego Sujo Basin, Teresópolis, RJ, an important agricultural pole whose production services the metropolitan region of Rio de Janeiro, water from different sources (spring, weir and river) was collected in this region, as well as samples of soil and lettuce irrigated with these waters, to carry out conventional microbiological analyzes (counts of total heterotrophic bacteria and thermotolerant coliforms) and molecular analyzes (PCR-DGGE). The count of fecal coliforms in lettuce suggests that there is an influence of irrigation water and the cultivated soil on the contamination of these vegetables. The grouping of bacterial communities in the different samples obtained by the PCR-DGGE technique shows that irrigation water has a greater influence on the contamination of these vegetables in relation to the soil where they are grown. These results corroborate the need to monitor water bodies used for irrigation and demonstrate that the PCR-DGGE technique is of great value for the study of microbial communities and, when associated with specific primers, can help in the detection of pathogens in food.
Highlights
Lettuce (Lactuca sativa) has been considered one of the most consumed vegetables in Brazil, mainly due to its organic characteristics, such as being low in calories and a rich fiber source, in addition to being a low cost food, qualifying for different diets (GOMES NETO et al, 2012)
Using molecular (PCR-DGGE) and conventional microbiological techniques, this study aimed to investigate the influence of different sources of irrigation water and cultivated soil on the microbiological quality of lettuce (Lactuca sativa) grown in the Córrego Sujo Basin (53 km2), Teresópolis, RJ, an important agricultural pole whose production services the metropolitan region of Rio de Janeiro
Coliforms and detection of pathogens such as Salmonella in these substrates have been used to evaluate the microbiological quality of these samples and consequent contamination, using DGGE technique to verify the influence of different sources of irrigation and cultivated soil in the composition of bacterial communities present in vegetables such as lettuce (ERCOLINI, 2004)
Summary
Lettuce (Lactuca sativa) has been considered one of the most consumed vegetables in Brazil, mainly due to its organic characteristics, such as being low in calories and a rich fiber source, in addition to being a low cost food, qualifying for different diets (GOMES NETO et al, 2012) It is the most important vegetable with green leaves in Brazil’s economy, with acreage of approximately 35,000 acres (KRINSKI; PELISSARI, 2012). To increase productivity, the use of organic fertilizers made from animal manure, homemade bio-fertilizers and slurries made of organic compounds that didn’t have time to complete composting lead to contamination of vegetables by potentially pathogenic bacteria Such practices can lead to various issues with the quality of cultivated foods, especially those that grow close to the soil (SIMÕES et al, 2001)
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