Bacterial Spores in Food: Survival, Emergence, and Outgrowth

Abstract

Spore-forming bacteria are ubiquitous in nature. The resistance properties of bacterial spores lie at the heart of their widespread occurrence in food ingredients and foods. The efficacy of inactivation by food-processing conditions is largely determined by the characteristics of the different types of spores, whereas food composition and storage conditions determine the eventual germination and outgrowth of surviving spores. Here, we review the current knowledge on variation in spore resistance, in germination, and in the outgrowth capacity of spores relevant to foods. This includes novel findings on key parameters in spore survival and outgrowth obtained by gene-trait matching approaches using genome-sequenced Bacillus spp. food isolates, which represent notorious food spoilage and pathogenic species. Additionally, the impact of strain diversity on heat inactivation of spores and the variability therein is discussed. Knowledge and quantification of factors that influence variability can be applied to improve predictive models, ultimately supporting effective control of spore-forming bacteria in foods.

Analysis of Germination Capacity and Germinant Receptor (Sub)clusters of Genome-Sequenced Bacillus cereus Environmental Isolates and Model Strains

“…This may be due to the requirement for different types or concentrations of certain germinants or combinations of germinants. A number of factors that can affect the GR-dependent germination have been previously discussed (12,20,41), including accessibility and the number of GRs or the downstream germination mechanisms. Moreover, genome-based studies may be affected by the quality of draft genomes, e.g., contig length, the presence of GR subunits (i.e., C subunits) on short contigs, and/or location of GRs or subunits (i.e., those in cluster X III ) at the contig's edge.…”

“…The spore germination process follows well-described sequential steps (11,12,20). Spore swelling of germinating spores and full rehydration of the core require hydrolysis of the peptidoglycan cortex layer.…”

“…Additional methods include measurement of Ca-DPA content by Raman spectroscopy, sometimes combined with laser tweezers (22)(23)(24), automated phase-contrast or differential interference contrast (DIC) microscopy, and time-lapse microscopy (for a review, see the paper by Wells-Bennik et al [20]). Alternatively, spore-staining approaches can be applied in combination with high-throughput analysis of individual spores using flow cytometry (FCM) (25)(26)(27).…”

Modified Green Tea Polyphenols, EGCG-S and LTP, Inhibit Endospore in Three <i>Bacillus</i> spp.

“…Untreated samples were used as controls. Triplicates were carried out; the mean, standard deviation (SD), and the percentage of germinated cells were determined by using Equation (3).…”

“…their high degree of resistance to heat, chemicals and ultraviolet (UV) radiation [1] [2] [3]. Bacillus spp.…”