Inactivation of Bacillus anthracis spores by a combination of biocides and heating under high-temperature short-time pasteurization conditions

Immediate and sensitive detection of sporulated Bacillus subtilis by microwave release and tandem mass spectrometry of dipicolinic acid

Spore lysis of Bacillus species is achieved by brief (1 min) microwave irradiation while tandem mass spectrometry (MS/MS) allows identification of the characteristic spore marker, dipicolinic acid. This rapid measurement, made on 10⁵-10⁸ spores, has significant implications for biothreat recognition.

Sporulation and germination gene expression analysis of Bacillus anthracis Sterne spores in skim milk under heat and different intervention techniques

To investigate how B. anthracis Sterne spores survive in milk under heat (80 degrees C, 10 min), pasteurization (72 degrees C, 15 s), microfiltration, and pasteurization and microfiltration, the expression levels of genes related to sporulation and germination were tested using real-time PCR assays. Twenty-seven sporulation- and germination-related genes were selected for the target genes. Our results demonstrated that gene expression levels were altered by heat and microfiltration whereas the pasteurization and pasteurization and microfiltration resulted in less alteration of gene expression. Heat activated and inhibited both sporulation- and germination-related genes, suggesting that bacterial spores underwent different molecular mechanism for heat treatments. Our results may provide some insight into the molecular mechanisms of spore survival in response to heat treatment and different intervention strategies used to treat fluid skim milk.

Thermal effects on bacterial bioaerosols in continuous air flow

Exposure to bacterial bioaerosols can have adverse effects on health, such as infectious diseases, acute toxic effects, and allergies. The search for ways of preventing and curing the harmful effects of bacterial bioaerosols has created a strong demand for the study and development of an efficient method of controlling bioaerosols. We investigated the thermal effects on bacterial bioaerosols of Escherichia coli and Bacillus subtilis by using a thermal electric heating system in continuous air flow. The bacterial bioaerosols were exposed to a surrounding temperature that ranged from 20 degrees C to 700 degrees C for about 0.3 s. Both E. coli and B. subtilis vegetative cells were rendered more than 99.9% inactive at 160 degrees C and 350 degrees C of wall temperature of the quartz tube, respectively. Although the data on bacterial injury showed that the bacteria tended to sustain greater damage as the surrounding temperature increased, Gram-negative E. coli was highly sensitive to structural injury but Gram-positive B. subtilis was slightly more sensitive to metabolic injury. In addition, the inactivation of E. coli endotoxins was found to range from 9.2% (at 200 degrees C) to 82.0% (at 700 degrees C). However, the particle size distribution and morphology of both bacterial bioaerosols were maintained, despite exposure to a surrounding temperature of 700 degrees C. Our results show that thermal heating in a continuous air flow can be used with short exposure time to control bacterial bioaerosols by rendering the bacteria and endotoxins to a large extent inactive. This result could also be useful for developing more effective thermal treatment strategies for use in air purification or sterilization systems to control bioaerosols.