Spoilage potential of psychrotrophic lactic acid bacteria (LAB) species: Leuconostoc gelidum subsp. gasicomitatum and Lactococcus piscium, on sweet bell pepper (SBP) simulation medium under different gas compositions

120

bRefrigerated food processing facilities are specific man-made niches likely to harbor cold-tolerant bacteria. To characterize this type of microbiota and study the link between processing plant and product microbiomes, we followed and compared microbiota associated with the raw materials and processing stages of a vacuum-packaged, cooked sausage product affected by a prolonged quality fluctuation with occasional spoilage manifestations during shelf life. A total of 195 samples were subjected to culturing and amplicon sequence analyses. Abundant mesophilic psychrotrophs were detected within the microbiomes throughout the different compartments of the production plant environment. However, each of the main genera of food safety and quality interest, e.g., Leuconostoc, Brochothrix, and Yersinia, had their own characteristic patterns of contamination. Bacteria from the genus Leuconostoc, commonly causing spoilage of cold-stored, modified-atmosphere-packaged foods, were detected in high abundance (up to >98%) in the sausages studied. The same operational taxonomic units (OTUs) were, however, detected in lower abundances in raw meat and emulsion (average relative abundance of 2% ؎ 5%), as well as on the processing plant surfaces (<4%). A completely different abundance profile was found for OTUs phylogenetically close to the species Yersinia pseudotuberculosis. These OTUs were detected in high abundance (up to 28%) on the processing plant surfaces but to a lesser extent (<1%) in raw meat, sausage emulsion, and sausages. The fact that Yersinia-like OTUs were found on the surfaces of a high-hygiene packaging compartment raises food safety concerns related to their resilient existence on surfaces. R efrigeration is used throughout the modern food chain to ensure the safety and quality of perishable products. Chilling has also been extended to food processing facilities to ensure that food manufacture complies with the legislative requirements governing maximum food temperature. Perishable food is usually packaged under a carbon dioxide-containing modified atmosphere to suppress bacterial growth. These modern food manufacturing practices have changed the order of prevalence of food-borne bacteria. Instead of aerobic Gram-negative bacteria, (facultatively) anaerobic Gram-positive bacteria prevail in modified-atmosphere-packaged (MAP) foods (1). In addition to refrigeration, the daily cleaning and sanitizing procedures used at the processing facilities might lead to the resilience of certain microbes and thus persistent contamination.Hygiene in a food processing facility is monitored through an internal control procedure, including hazard analysis of critical control points. The manufacturer is responsible for guaranteeing the safety and quality of its products during the shelf life set for each respective product. In routine hygiene monitoring, the microbiological quality of the raw materials, cleanliness of the surfaces, and quality of the end products are included in these internal control protocols. Bacterial contaminat...

Section: Discussionmentioning

confidence: 91%

Meat Processing Plant Microbiome and Contamination Patterns of Cold-Tolerant Bacteria Causing Food Safety and Spoilage Risks in the Manufacture of Vacuum-Packaged Cooked Sausages

Hultman

Rahkila

Ali

et al. 2015

120

“…The spoilage-related populations can be studied as a consortium with the help of culture-independent approaches in order to look at changes to the composition of the microbial communities in response to environmental factors related to food storage, such as temperature and packaging technology (19,20), as well as technological parameters (21). However, the isolation and characterization of spoilage microorganisms from food are also fundamental in order to differentiate the biotype-specific traits that delineate the intraspecies diversity (22)(23)(24)(25). The spoilage of food is a complex phenomenon; in ready-to-eat (RTE) foods, it usually occurs with off odors, acidification, and appearance defects (26)(27)(28).…”

mentioning

confidence: 99%

Processing Environment and Ingredients Are Both Sources of Leuconostoc gelidum, Which Emerges as a Major Spoiler in Ready-To-Eat Meals

Pothakos

Stellato

Ercolini

et al. 2015

Self Cite

bMesophilic and psychrotrophic organism viable counts, as well as high-throughput 16S rRNA gene-based pyrosequencing, were performed with the aim of elucidating the origin of psychrotrophic lactic acid bacteria (LAB) in a ready-to-eat (RTE) meal manufacturing plant. The microbial counts of the products at the end of the shelf life were greatly underestimated when mesophilic incubation was implemented due to overlooked, psychrotrophic members of the LAB. Pseudomonas spp., Enterobacteriaceae, Streptococcaceae, and Lactobacillus spp. constituted the most widespread operational taxonomic units (OTUs), whereas Leuconostoc gelidum was detected as a minor member of the indigenous microbiota of the food ingredients and microbial community of the processing environment, albeit it colonized samples at almost every sampling point on the premises. However, L. gelidum became the most predominant microbe at the end of the shelf life. The ability of L. gelidum to outgrow notorious, spoilagerelated taxa like Pseudomonas, Brochothrix, and Lactobacillus underpins its high growth dynamics and severe spoilage character under refrigeration temperatures. The use of predicted metagenomes was useful for observation of putative gene repertoires in the samples analyzed in this study. The end products grouped in clusters characterized by gene profiles related to carbohydrate depletion presumably associated with a fast energy yield, a finding which is consistent with the fastidious nature of highly competitive LAB that dominated at the end of the shelf life. The present study showcases the detrimental impact of contamination with psychrotrophic LAB on the shelf life of packaged and cold-stored foodstuffs and the long-term quality implications for production batches once resident microbiota are established in the processing environment.T heoretically, a food commodity harbors a wide range of different microorganisms (1) associated with the ecological niches wherefrom foods originate. This initial diverse community can be enriched by other biota after transportation to industrial production facilities (2). Due to handling during processing and storage, microbes are eventually subjected to a selection pressure (3), which defines a dominant microbial consortium. In this way, certain members of this association proliferate greatly and cause alterations constituting the specific spoilage organisms (SSOs) (4). In the past few years in Belgium, the persisting problem of psychrotrophic lactic acid bacteria (LAB) prevailing at the end of the shelf life of packaged and refrigerated foodstuffs has been substantiated (5-7). These cold-adapted species of LAB contaminate foods from numerous industrial plants, but little is known about their environmental occurrence and the possible contamination routes. Their introduction in production lines can be mediated by crude material, given the fact that LAB are ubiquitous in plant ecosystems and also constitute the commensal biota of livestock (8-10). Moreover, there is emerging evidence that psychrotrophic LAB ...

“…Lately, L. gelidum subsp. gasicomitatum has also been associated with the spoilage of packaged and chill-stored vegetables, and the production of diacetyl/acetoin has been verified on a sweet pepper simulation medium (4,21). Thus, understanding the function of the diacetyl/acetoin pathways of this bacterium is crucial, considering the wide range of foods it affects.…”

Section: Discussionmentioning

confidence: 99%

“…During the past 14 years, L. gelidum subsp. gasicomitatum has been associated with the spoilage of cold-stored, modified-atmosphere-packaged (MAP), nutrient-rich foods (2,3,4,5). It has also been reported as an important species in the fermentation of kimchi, a traditional Korean food made by fermenting vegetables at refrigerator temperatures (6).…”

mentioning

confidence: 99%

See 1 more Smart Citation

Production of Buttery-Odor Compounds and Transcriptome Response in Leuconostoc gelidum subsp. gasicomitatum LMG18811 ^T during Growth on Various Carbon Sources

Jääskeläinen

Vesterinen

Parshintsev

et al. 2015

Leuconostoc gelidum subsp. gasicomitatum is a common spoilage bacterium in meat products packaged under oxygen-containing modified atmospheres. Buttery off-odors related to diacetyl/acetoin formation are frequently associated with the spoilage of these products. A whole-genome microarray study, together with gas chromatography (GC)-mass spectrometry (MS) analyses of the pathway end products, was performed to investigate the transcriptome response of L. gelidum subsp. gasicomitatum LMG18811 T growing on semidefined media containing glucose, ribose, or inosine, which are essential carbon sources in meat. Generally, the gene expression patterns with ribose and inosine were quite similar, indicating that catabolism of ribose and nucleosides is closely linked. Diacetyl/acetoin concentrations as high as 110 or 470 M were measured when growth was based on inosine or ribose, respectively. The gene expression results for pyruvate metabolism (upregulation of ␣-acetolactate synthase, downregulation of L-lactate dehydrogenase and pyruvate dehydrogenase) were as expected when diacetyl and acetoin were the end products. No diacetyl production (<7.5 M) was detected with the glucose-containing medium, even though the cell counts of LMG18811T was 6 or 10 times higher than that on inosine or ribose, respectively. Although glucose was the most effective carbon source for the growth of L. gelidum subsp. gasicomitatum, utilization of inosine and ribose resulted in the production of the unwanted buttery-odor compounds. These results increase our understanding of which compounds are likely to enhance the formation of buttery odors during meat spoilage caused by L. gelidum subsp. gasicomitatum. Leuconostoc gelidum is a psychrotrophic lactic acid bacterium (LAB) comprising three subspecies, i.e., Leuconostoc gelidum subsp. gelidum, Leuconostoc gelidum subsp. gasicomitatum, and Leuconostoc gelidum subsp. aenigmaticum (1). During the past 14 years, L. gelidum subsp. gasicomitatum has been associated with the spoilage of cold-stored, modified-atmosphere-packaged (MAP), nutrient-rich foods (2, 3, 4, 5). It has also been reported as an important species in the fermentation of kimchi, a traditional Korean food made by fermenting vegetables at refrigerator temperatures (6). The first scientific publications on L. gelidum subsp. gasicomitatum associated it with spoilage of raw MAP meat products in Scandinavia (2, 3, 7), but spoilage cases associated with fish (8) and vegetable products (9) have also been reported. Recently, this versatile food spoilage organism has been linked to spoilage cases affecting packaged meat, vegetable, and composite foods in Western Europe (4, 5, 10).Leuconostoc gelidum subsp. gasicomitatum cannot obtain energy from glycogen, proteinaceous substrates, lactate, or fatty acids (11), and its growth is based mainly on the utilization of carbohydrates. As an obligately heterofermentative LAB, it ferments hexoses and pentoses by the phosphoketolase pathway (PKP). In marinated meat products, L. gelidum subsp. gasicomitatum ...