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Morphological and phenotypical characterization of Bacillus sporothermodurans
Author(s) -
Montanari G.,
Borsari A.,
Chiavari C.,
Ferri G.,
Zambonelli C.,
Grazia L.
Publication year - 2004
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1111/j.1365-2672.2004.02371.x
Subject(s) - microbiology and biotechnology , biology , phenotype , bacillales , bacillaceae , bacteria , genetics , bacillus subtilis , gene
Aims: Enumeration of resistant bacteria in ultra‐high temperature (UHT) treated milk; morphological characterization and phenotyping of resistant strains by traditional and nontraditional methods and their identification by molecular biology. Methods and Results: Modified standard plate count agar (PCA) and modified brain–heart infusion (BHI) agar were used for colony counts. Physiological culture traits were determined as suggested by Bergey's Manual of Systematic Bacteriology or in modified J‐broth or in modified BHI agar. Scanning electron microscope (SEM) was used for microscopic examination. Strain identification was carried out by polymerase chain reaction (PCR). A total of 125 (62·81% of 199) samples were positive and the bacterial load was higher than 10 5 CFU ml −1 in 46 samples (28·80% of 125). The 16S rRNA sequence of bacterial cultures obtained from UHT‐treated milk was similar to that of Bacillus sporothermodurans M215 type strain (T) and different biotypes were found by analysis of colony appearance, cell morphology and physiological traits. Conclusions: Bacillus sporothermodurans was the predominant sporigenous micro‐organisms in UHT milk. Significance and Impact of the Study: BHI agar is more suitable than PCA for quality control of milk after UHT treatment. Modified J‐broth medium is useful to determine selected physiological traits of B. sporothermodurans . The strains characterized and identified as B. sporothermodurans were significantly different compared with the type strain.