Dados do Trabalho

Título

EVALUATION OF MICROORGANISMS PRESENT IN LETTUCE (LACTUCA SATIVA) SOLD AT STREET MARKETS IN A NORTHEASTERN CITY OF BRAZIL

Introdução

Lettuce (Lactuca sativa), a widely consumed vegetable in salads owing to its nutritional content, can also serve as a vehicle for pathogenic microorganisms due to exposure during cultivation, handling, and marketing. To prevent foodborne illnesses, the proper cleaning of lettuce before consumption is essential. In this context, the present study aimed to assess the presence of microorganisms in lettuce sold in open air markets.

Material e Métodos

Lettuce samples were purchased and subjected to three different conditions: cleaning in a 200 ppm sodium hypochlorite solution for 15 min, washing with water, and no cleaning. The samples were homogenized in peptone water with a 1 ml aliquot cultured on Levine Agar plates (EMB) and incubated at 35 °C for 48 h. Based on the morphological and physiological characteristics, bacterial colonies were isolated on Nutrient Agar plates and incubated at 35 °C for 24 h, followed by Gram staining and microscopy of the isolated bacterial strains.

Resultados e Discussão

The results indicated the absence of Escherichia coli, suggesting that there was no fecal contamination in the samples. However, it is noteworthy that in addition to the proliferation of microorganisms in the samples that were only washed with water and not cleaned, bacterial growth was also observed in the sample that was sanitized with sodium hypochlorite. The presence of microenvironments within lettuce leaves may have protected the microorganisms from contact with the sanitizer, which can be invoked as an explanation for this phenomenon. In total, 27 strains of gram-negative bacteria were isolated, as expected, given the selectivity of EMB medium for this type of microorganism.

Conclusão

This outcome implies potential microbial diversity that may be related to inadequate hygiene practices. Although the absence of Escherichia coli is a favorable indication, the presence of a diverse range of gram-negative microorganisms underscores the necessity for enhanced hygiene measures. Therefore, it is recommended that additional agitation be incorporated during hypochlorite-based sanitation procedures to increase the contact of the sanitizer with the microsurfaces of the leaves, with the aim of achieving more effective sanitation.