Morphological and phenotypical characterization of Bacillus sporothermodurans

Abstract

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 (62AE81% of 199) samples were positive and the bacterial load was higher than 10 5 CFU ml )1 in 46 samples (28AE80% 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.

Incidence and characterisation of aerobic spore‐forming bacteria originating from dairy milk in Tunisia

“…; Montanari et al . ). Their vegetative cells cause a slight change in the colour of the milk, off flavours and destabilisation of casein micelles (Klijn et al .…”

“…; Montanari et al . ; Scheldeman et al . ), to our knowledge, no reports from Tunisia are available.…”

Characterization of Aerobic Spore-Forming Bacteria Isolated From Raw Milk, Skim Milk Powder and UHT Milk

“…isolates from UHT milk samples. Klijn et al (1997), Montanari et al (2004) demonstrated that B. sporothermodurans was the predominant sporigenous micro-organisms in UHT milk. Cosentino et al (1997) reported the presence of aerobic spore formers, including B. sphaericus, B. licheniformis and B. brevis, in Sardinian UHT milk samples.…”

“…To achieve this, the nature and origin of spores and in particular of spores in raw milk must be better understood. Although the incidence of Bacillus species in dairy products from different geographical areas has been widely investigated (Montanari et al, 2004, Scheldeman et al, 2005.…”

Inactivation of Bacillus sporothermodurans LTIS27 spores by high hydrostatic pressure and moderate heat studied by response surface methodology

“…The identification was confirmed by sequencing the 16S rRNA gene after PCR amplification as described by Winker and Woese (1991). B. sporothermodurans LTIS27 presents a high degree of similitude (99.8%) with the reference strain M215T type II regarding 16S rRNA gene sequences (Aouadhi et al, 2012), a specific strain of the UHT milk and named HRS clone (Montanari et al, 2004).…”