Growth Inhibitory Effect of 2-Nitropropanol on Foodborne Bacteria of Public Health Importance

Abstract

The investigation was aimed at to proximate the minimum inhibitory concentration (MIC) of 2-nitropropanol (2-NPOH) for growth inhibition (in-vitro) of Salmonella typhimurium, Shigatoxic Escherichia coli (STEC) and Salmonella gallinarum vis a vis effect of pH of culture medium on function of 2-NPOH and its in-vivo effect on these bacteria in chick model. In in-vitro testing, MIC of 2-NPOH for Salmonella typhimurium was recorded to be 3.5 mM whereas it was 1.5 mM for STEC and Salmonella gallinarum. These organisms were sensitive to acidic pH of the growth medium. Increasing pH of the medium viz. 7.3, 8.0, 8.5, 9.0 and 9.5 (without adding 2-NPOH) revealed that higher alkalinity did not affect growth status of these organisms. On the analogy, growth medium supplemented with sub-MIC dosage of 2-NPOH in different alkaline pH (8.0, 8.5, 9.0 and 9.5) although exerted its bacteriostatic effect; but had no significant variation on growth at different pH (> 8.0). In-vivo effect of 2-NPOH in chick model (4 days old) revealed that its MIC dosages may considerably reduce carriage of intestinal bacteria like Salmonella typhimurium (26x107 to 10.5x106 cfu/gm of faeces), STEC (33x107 to 11.2X106cfu/gm faeces) and Salmonella gallinarum (29x107 to 9.4x106cfu/gm of faeces). Above all, the findings suggested that 2-NPOH may be used as substitute of antibiotic to reduce the carriage of gut microbiota of public health importance in poultry.