The Presumptive Enumeration of Lactose Negative as well as Lactose Positive Enterobacteriaceae in Foods

Abstract

Sorbic acid as a selective agent in cucumber fermentations. I. Effect of sorbic acid on microorganisms associated with cucumber fermentations. Appl. Microbiol.,

CEPHALOTRICHOUS, FERMENTATIVE GRAM‐NEGATIVE BACTERIA: THE GENUS AEROMONAS

“…Growth and reaction on media diagnostic f c r wli-aerogenes bacteria. All strains were tested on the CNBLM medium of Mossel (1957). The lactose fermenting strains were tested on MacConkey's broth, MacConkey's agar (Oxoid No.…”

“…Table 4. The reactions of luctose-fermenting Aeromonas strains at 37" and 30" in two broth media and their colony wlours on two agar media All the strains were tested on the CNBLM medium of Mossel (1957) which was devised for the detection of most Enterobacteriaceae, whether fermenting lactose or not, following the suggestion by Henriksen (1955) that the lactose in diagnostic media be replaced by mannitol. All the strains tested were positive at 37", except 141 and 161-164, which failed to grow, and a t 30" except 162 and 163, which failed to grow a t this temperature also.…”

“…It is therefore probable that they would occur on chilled foods and equally likely that, if isolated, most of them would be dismissed as paracolons, particularly if incubation were at 30" rather than a t 37", a practice which is becoming increasingly common. Further, all the Aeromnas strains gave a positive result on the CNBLM medium recommended by Mossel (1957) for the detection of Enterobacteriaceae, whether able to ferment lactose or not ; hence Aeromonas, which is clearly not related to this family, may have been present but overlooked when this medium has been used (e.g. Krol & Moerman, 1959-60).…”

The Significance of Various Organisms of Faecal Origin in Foods and Drinking Water

“…It is therefore much better to replace the use of lactose media by those containing mannitol, as suggested many years ago by Bulir (1907) and advocated again by Henriksen (1955) and Mossel (1957). Particularly recommended for this purpose is MacConkey's (1905) crystal violet-neutral red-bile agar ('violet-red-bile agar') to which 1% of D-mannitol is added.…”

The Rapid Tentative Recognition of Psychro‐trophic Types Among Enterobacteriaceae Isolated From Foods

“…Twenty-six of these were authentic strains of the genera Escherichia, Aerobacter, Citrobacter, Serratia, Salmonella, Shigella, Hafnia and Proteus, which did not develop within 60 days a t 6", while the other 39 could do this and can therefore be considered psychrotrophic strains. Of the latter, 26 were isolated from ice cream and raw meatsnacks ('snack tartar') which had been stored for about 2 weeks a t 2-3" by plating on crystal violet-neutral red-bile-lactose-mannitol (CNBLM) agar (Mossel, 1957 Medium, inoculation and incubation. Fresh 30" cultures of all the strains were streaked on TDYM agar, a nonselective medium found to be very suitable for general subculturing by Mossel & Krugers Dagneaux (1959)) and replicate tubes were incubated at 39.5, 42, 43 and 44".…”