Coliphage as an indicator of fecal contamination in hydroponic cucumber (Cucumis sativus L) greenhouses
2005
Xu, J. | Warriner, K.
A preliminary study has been performed to evaluate the utility of somatic and F(+)-specific coliphage as quality indicators of irrigation water used in hydroponic cucumber greenhouse operations. Samples of incoming water, waste hydroponic solution, cucumber fruit and plant roots derived from two greenhouses were screened for bacterial fecal indicators (generic Escherichia coli, fecal coliforms, total coliforms and Clostridium perfringens) and coliphage. Bacterial fecal indicators were present in incoming water and in spent hydroponic solution with coliphage only being sporadically recovered. However, both somatic and F(+)-specific coliphage were consistently recovered from the roots of cucumber plants along with bacterial fecal indicators. Despite the heavy contamination of plant roots, the cucumber fruits were within acceptable microbiological limits. F(+)-specific coliphage was recovered from 1 out of 25 cucumbers tested along with generic E coli. In contrast, no somatic coliphage was recovered from cucumbers despite coliforms being present on 15 out of 25 units. In conclusion, coliphage represents a poor index of hydroponic irrigation water quality but presence on cucumber fruit and roots can be used to highlight the presence of fecal indicator bacteria within greenhouse operations.
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