Helicobacter pylori growth pattern in reference media and extracts from selected minimally processed vegetables

Abstract

[EN] Helicobacter pylori is an emergent foodborne pathogen of concern, the entrance of which into the food chain has been recently related with the possible contamination of raw or minimally processed vegetables. The present study documented the growth kinetics of the bacterium at 5, 20 and 37 degrees C, in reference media and vegetable substrates, to be fitted to the Gompertz equation. H. pylori was able to grow at 37 degrees C and 20 degrees C, but not at refrigeration temperature. Incubation temperature decrease significantly (p-value < 0.05) affected growth kinetic parameters, with the elongation of lag phase duration (lambda) and the reduction of the maximum specific growth rate (mu(max)) (0.10 log(10)(CFU/ml)/h at 37 degrees C; 0.04 log(10)(CFU/ml)/h at 20 degrees C). In vegetable extracts, the microorganism remained in a viable culturable (VC) form for a maximum of 5 days (20 degrees C), being unable to grow significantly in chard, spinach and in kale. In lettuce, H. pylori achieved growth of close to 1 log(10) cycle (after 5 days at 20 degrees C) (mu(max) 0.79 log(10)(CFU/ml)/d).

The present study is the first reporting kinetic parameter values describing the growth behavior of H. pylori at its optimum growth temperature and, also studying the most relevant handling temperatures for minimally processed vegetables: commercial distribution (room temperature 20 degrees C), and refrigeration temperature. (C) 2017 Elsevier Ltd. All rights reserved.