Scanning electron microscopy of Salmonella biofilms on various food-contact surfaces in catfish mucus.

The objective of this study was to determine the growth and survival of Salmonella enterica in the presence of high and low concentrations (375 μg/ml and 15 μg/ml) of catfish mucus extract at 10 °C and 22 °C for 63 days. The second objective of this study was to investigate the biofilm formation of Salmonella enterica serovar Blockley (7175) in catfish mucus extract for 48 h at 22 °C on four food-contact surfaces and to observe the biofilm populations using Scanning Electron Microscopy (SEM). The surface properties, surface roughness and surface energies were determined using contact angle measurement and atomic force microscopy. In 375 μg/ml of catfish mucus extract that was inoculated with 3 log CFU/ml, the growth of Salmonella counts were increased to a maximum of 6-7 log CFU/ml at 10 °C and 7-8 log CFU/ml at 22 °C in 7-14 d and decreased by 1-2 log CFU/ml from these peak levels at both 10 °C and 22 °C from 21 to 63 d. In 15 μg/ml of catfish mucus extract, Salmonella counts were in the range of 4-5 log CFU/ml at 10 °C and 5-6 log CFU/ml at 22 °C over 7-63 d of storage. By contrast, Salmonella counts were non-detectable in the absence of catfish mucus by 21-28 d of storage at 10 °C or 22 °C. The biofilm counts of S. Blockley (7175) on a stainless steel surface were 4 log CFU/cm2 and 5.5 log CFU/cm2 in 15 μg/ml and 375 μg/ml of catfish mucus extract respectively after 48 h incubation at 22 °C. SEM revelead t...

Source: Food Microbiology - May 2, 2018 Category: Food Science Authors: Dhowlaghar N, Bansal M, Schilling MW, Nannapaneni R Tags: Food Microbiol Source Type: research