Handbook of Culture Media for Food and Water Microbiology
Chapter 21: Culture Media for Food Spoilage Bacteria of the Order Pseudomonadales: Pseudomonas, Acinetobacter and Psychrobacter spp.
Published:06 Dec 2011
Special Collection: 2011 ebook collection , 2011 ebook collection , 2011-2015 food science subject collection
Patrick Druggan, Carol Iversen, 2011. "Culture Media for Food Spoilage Bacteria of the Order Pseudomonadales: Pseudomonas, Acinetobacter and Psychrobacter spp.", Handbook of Culture Media for Food and Water Microbiology, Janet E L Corry, Gordon D W Curtis, R M Baird
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In recent years the taxonomy of organisms commonly referred to as “pseudomonads” has been updated and many species formerly included in the genus Pseudomonas (order Pseudomonadales) have been allocated to other orders, such as Aeromonadales, Alteromonadales, Burkholderiales, Caulobacterales, Neisseriales, Oceanospirillales, Rhizobiales, Rhodocyclales, Rhodospirillales, Sphingomonadales and Xanthomonadales. Hydrogen sulfide-producing pseudomonads are assigned to Shewanella putrefaciens (family Shewanellaceae; order Alteromonadales). Colonies of these are generally salmon pink in colour, pink-pigmented, negative for arginine dihydrolase and capable of producing DNAse. They are important spoilage organisms of meat and fish and can be isolated using Lyngby iron agar comprising (g L−1): peptone (20), NaCl (5), beef extract (3), yeast extract (3), L-cysteine (0.6), FeC6H5O7·3H2O (0.3), Na2S2O3 (0.3) and agar (15); final pH 7.4±0.2. Incubation is aerobic at 20–25°C for 3 days using pour plating. Food spoilage bacteria in the order Pseudomonadales consist primarily of Pseudomonas, Acinetobacter and Psychrobacter spp. Acinetobacter and Psychrobacter are placed in the family Moraxellaceae, along with Moraxella, which comprises parasitic species with low pathogenicity commonly found on mucous membranes; these species are not generally associated with food spoilage.