Microbial Successions Are Associated with Changes in Chemical Profiles of a Model Refrigerated Fresh Pork Sausage during an 80-Day Shelf Life Study

Abstract

bFresh pork sausage is produced without a microbial kill step and therefore chilled or frozen to control microbial growth. In this report, the microbiota in a chilled fresh pork sausage model produced with or without an antimicrobial combination of sodium lactate and sodium diacetate was studied using a combination of traditional microbiological methods and deep pyrosequencing of 16S rRNA gene amplicons. In the untreated system, microbial populations rose from 10 2 to 10 6 CFU/g within 15 days of storage at 4°C, peaking at nearly 10 8 CFU/g by day 30. Pyrosequencing revealed a complex community at day 0, with taxa belonging to the Bacilli, Gammaproteobacteria, Betaproteobacteria, Actinobacteria, Bacteroidetes, and Clostridia. During storage at 4°C, the untreated system displayed a complex succession, with species of Weissella and Leuconostoc that dominate the product at day 0 being displaced by species of Pseudomonas (P. lini and P. psychrophila) within 15 days. By day 30, a second wave of taxa (Lactobacillus graminis, Carnobacterium divergens, Buttiauxella brennerae, Yersinia mollaretti, and a taxon of Serratia) dominated the population, and this succession coincided with significant chemical changes in the matrix. Treatment with lactate-diacetate altered the dynamics dramatically, yielding a monophasic growth curve of a single species of Lactobacillus (L. graminis), followed by a uniform selective die-off of the majority of species in the population. Of the six species of Lactobacillus that were routinely detected, L. graminis became the dominant member in all samples, and its origins were traced to the spice blend used in the formulation.

The use of 16S rRNA gene metagenetic monitoring of refrigerated food products for understanding the kinetics of microbial subpopulations at different storage temperatures: the example of white pudding

“…Fortunately, molecular technologies can elucidate the microbial communities, including the identification and quantification of culturable and non-culturable organisms, and can do so at a much higher resolution than was previously possible with culture-based methods (Kergourlay et al, 2015;Elizaquível et al, 2015). Many bacterial species putatively responsible for food spoilage have been reported, thanks to the development of high throughput sequencing methods, that allow for a more detailed and deeper description of bacterial species present in food (Benson et al, 2014;Chaillou et al, 2014;Delcenserie et al, 2014;Galimberti et al, 2015;Riquelme et al, 2015). These works are mainly limited to the description of the product's microbiota during its shelf life.…”

Reducing Salt in Raw Pork Sausages Increases Spoilage and Correlates with Reduced Bacterial Diversity

“…Toward this end, two culture-independent analyses of raw or cooked pork sausages were recently published. Benson and coworkers (25) revealed complex dynamics of about 20 taxa during the storage of raw pork sausages at 4°C. This study also illustrated the role of spices as a source of spoiling bacterial species and demonstrated the important role of sodium-and acid-based preservatives (sodium lactate and sodium diacetate), first, in reducing spoilage of sausages, and second, in hindering the growth of the dominant spoilage bacteria Lactobacillus graminis and Carnobacterium divergens.…”

Companies seek food safety using a microbiome approach

“…Microbial geneticist Andrew Benson of the University of NebraskaLincoln, used DNA sequencing of the 16S rRNA gene to track the microbiome of refrigerated fresh pork sausage over an 80-day period (2). "We picked up ecological successions-waves of growth of organisms and the demise of others," he says.…”