Microbiology of Root Crops, Edible Corms, Tubers, Bulbs, and Rhizomes: An Endobacteriological Study

Abstract

A variety of root crops, corms, tubers, and rhizomes commonly eaten and available in public markets were tested for the presence and identification of bacteria in their inner flesh. Bacteria were grown on agar slants and identified by DNA sequence analysis. Among foods tested were various radishes, onions, shallots, leeks, yams, parsnips, turnips, carrots, potatoes, ginger, garlic, parsnips, beets, horse radish, kohl-rabi, and less well-known crops such as yucca/cassava, celery root/celeriac, jicama, taro, lotus, water chestnut, Chinese/Korean yam (nagaimo), edible burdock (golden gobo), batata, root parsley, and yautia (malanga). Examples of the bacterial genera identified were, among others, species of Arthrobacter, Pantoea, Bacillus, Pseudomonas, Staphylococcus, Microbacterium, Stenotrophomonas, Rahnella, Rhodococcus, Paenibacillus, Oerskovia, Gordonia, and Leclercia. While these species are probably present in harmless numbers, their presence may indicate that the inner flesh of these crops should be studied more extensively. Crops that are boiled, fried, baked or otherwise cooked may obviously not be a health hazard, but some of these vegetables are eaten raw or only lightly cooked and may possibly merit further study for possible health implications. Tubers that were very proficient in producing new shoots, such as potato and the Chinese/Korean yam (nagaimo) were found to contain inner flesh free of bacteria and seemed to be resistant to rotting; this may imply that these tubers have antimicrobial properties.