Table of Contents
What is meant by psychrotrophic bacteria?
Introduction. The term psychrotrophs (also denominated psychrotolerant) refers to microorganisms that have the ability to grow at low temperatures but have optimal and maximal growth temperatures above 15 and 20 °C, respectively (Moyer and Morita, 2007).
Which of these bacteria is psychrotrophic?
Psychrotrophic bacteria found in raw milk include the gram-negative genera Pseudomonas, Aeromonas, Serratia, Acinetobacter, and Hafnia and the gram-positive genera Bacillus, Microbacterium, Staphylococcus, and Carnobacterium (84, 103, 116).
What are psychrotrophic organisms what is their importance?
Psychrotrophic bacteria are capable of spoiling milk by biochemically altering the compounds present in milk. Psychrotrophs can cause the decomposition of urea, reduction of nitrate to nitrite and hydrolyses of proteins and lipids at temperatures as low as subzero.
Are psychrotrophic bacteria Gram positive or negative?
Gram-negative
Most psychrotrophic bacteria present in raw milk belong to the family Pseudomonadaceae, which includes Gram-negative, non-spore-forming, nonfermentative, aerobic rods. Pseudomonas fluorescens is the species most commonly isolated from milk, with Ps.
What is the difference between psychrophilic and psychrotrophic?
Psychrotrophic microorganisms have a maximum temperature for growth above 20 degrees C and are widespread in natural environments and in foods. Psychrophilic microorganisms have a maximum temperature for growth at 20 degrees C or below and are restricted to permanently cold habitats.
What is the difference between psychrophilic and psychrotrophic bacteria?
What are the Psychrotrophic bacteria found in food?
Most psychrotrophic bacteria found in food are species of Acinetobacter, Aeromonas, Bacillus, Clostridium, Klebsiella, Esherichia, Lactobacillus, Listeria, Morexella, Pseudomonas, Serratia, Streptococcus etc. ( 3 ).
What microorganisms can cause spoilage of dairy products?
Microorganisms that can cause spoilage of dairy products include Gram-negative psychrotrophic microorganisms (genera Pseudomonas, Aeromonas, Alcaligenes and Flavobacterium), coliforms, LAB, sporeforming bacteria and yeasts and moulds. Growth of psychrotrophic microorganisms in raw milk can lead to the production of degradative enzymes
How do psychrotrophs spoil milk?
Psychrotrophic bacteria are capable of spoiling milk by biochemically altering the compounds present in milk. Psychrotrophs can cause the decomposition of urea, reduction of nitrate to nitrite and hydrolyses of proteins and lipids at temperatures as low as subzero.
What are the Psychrotrophic bacteria in milk?
Most psychrotrophic bacteria present in raw milk belong to the family Pseudomonadaceae, which includes Gram-negative, non-spore-forming, nonfermentative, aerobic rods. Pseudomonas fluorescens is the species most commonly isolated from milk, with Ps. fragi and Ps. putida being of less importance.