ISOLATION OF BDELLOVIBRIOS THAT PREY ON ESCHERICHIA COLI O157:H7 AND SALMONELLA SPECIES AND APPLICATION FOR REMOVAL OF PREY FROM STAINLESS STEEL SURFACES¹

Abstract

Predatory bacteria of the genus Bdellovibrio that prey upon Escherichia coli O157:H7 and Salmonella species were isolated from soil and sewage samples. Bdellovibrio isolates 45k (from soil) and 88e (from sewage) attacked and lysed the E. coli and Salmonella strains tested, with log10 reductions ranging from 2.5 to 7.9 CFU/mL after 7h incubation, using a two‐membered culture system. The predators showed activity against the bacteria within the temperature range of 19 to 37C. Bdellovibrio isolate 45k reduced a population of E. coli dried on stainless steel surfaces by 3.6 log10 CFU/cm2 following 24 h contact time and at a 10:1 predator to prey ratio and was also effective in reducing the level of biofilm cells. Bdellovibrios can potentially be utilized for removal of bacteria from surfaces of food processing equipment and possibly for controlling the growth of pathogenic and spoilage bacteria in foods.

Removal of bacterial indicators and pathogens from domestic wastewater by the multi-soil-layering (MSL) system

“…Shilo (1966) and Lambina et al (1987) confirmed that these bacteria play a role in controlling the population size of bacteria in biofilms. In this context, Fratamico and Cooke (1996) showed that these bacteria reduced the number of E. coli by two logs, which suggests that these predatory bacteria could usefully serve as agents for the control of pathogens. Moreover, Markelova (2010) confirmed that Bdellovibrio caused lysis of Alcaligenes sp., Campylobacter sp., Erwinia sp., Escherichia sp., Helicobacter sp., Pseudomonas sp., Legionella sp.…”

The dual probiotic and antibiotic nature of Bdellovibrio bacteriovorus

“…Starting about a decade later, researchers began to think about the possible application of this unique bacteria in different applications, such as in fighting plant pathogens (10) and in reducing bacterial numbers/contamination in food industries (11). However, researchers were limited in their potential applications since genetic tools and knowledge were both limited, particularly for this bacterium.…”

“…However, the incubation period required was extended compared to tests performed at higher temperatures (30 and 37 o C). In another study by the same group, the authors wanted to test the ability of B. bacteriovorus to remove the gram negative bacteria from the surfaces of food processing equipment (11). Their isolated strains of B. bacteriovorus were capable of lysing E. coli O157：H7 and Salmonella sp.…”

“…The lack of these tools and plasmids did not hinder early researchers from beginning research into therapeutic applications of BALO (11,19), with one group even applying for a patent in France highlighting the use of Bdellovibrios in the treatment of gastrointestinal diseases (referenced in (20)). A search of the literature shows that different research groups around the world are concentrating more on this area nowadays (20)(21)(22)(23)(24)(25), with all of these studies being published within the last two years.…”

Bacterial predator–prey dynamics in microscale patchy landscapes

“…Does fragmentation increase the persistence of the prey population? Furthermore, given that B. bacteriovorus has shown potential to protect crops and reduce biofouling [26][27][28][29], it would be useful to know how its effectiveness in structured habitats relates to its effectiveness as measured in well-mixed (unstructured) culture flasks [30][31][32]. In this regard, B. bacteriovorus has also attracted significant interest because of its potential to eradicate bacterial biofilms which are spatially structured at the microscale [33,34].…”