Identification of proteolytic pseudomonads isolated from raw milk

Area of Science:

• Microbiology
• Bacteriology
• Food Science

Background:

• Proteolytic pseudomonads are microorganisms found in raw milk.
• These bacteria can impact milk quality through enzymatic activity.

Purpose of the Study:

• To classify proteolytic pseudomonads isolated from raw milk using numerical taxonomy.
• To differentiate between Pseudomonas species based on their biochemical and hydrolytic characteristics.

Main Methods:

• Numerical taxonomy and unweighted pair-group average-linkage cluster analysis were employed.
• Fifty-two characters were used to analyze 49 bacterial strains, including 26 Pseudomonas species.
• Identification was based on Bergey's Manual of Determinative Bacteriology.

Main Results:

• The milk isolates clustered into two main groups: Pseudomonas fluorescens and Pseudomonas fragi.
• Pseudomonas fluorescens isolates hydrolyzed milk proteins and fat, and produced phospholipase.
• Pseudomonas fragi-like isolates hydrolyzed milk proteins and fat but lacked phospholipase and fluorescent pigment production.

Conclusions:

• Numerical taxonomy effectively differentiated proteolytic pseudomonads in raw milk.
• The identified Pseudomonas species exhibit distinct enzymatic activities relevant to milk spoilage.
• Substrate and testing conditions are critical factors influencing the observed hydrolytic characteristics.