Marta Dušková

Identification of lactobacilli isolated from food by genotypic methods and MALDI-TOF MS

Lactobacilli are bacteria with important implications in food and feed fermentation. Detailed knowledge of the lactobacilli composition is of high relevance to food and health control, various industrial or biotechnological applications, etc., but accurate identification of the Lactobacillus species is not an easy task. In this study, three methods, i.e. polymerase chain reaction (PCR), amplified 16S rDNA restriction analysis with restrictase MseI (16S-ARDRA), and the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) were evaluated for their capabilities to identify Lactobacillus species. After comparison of the three methods on a set of 19 type/reference Lactobacillus strains, 148 strains isolated from dairy and meat products were characterized by PCR and MALDI-TOF MS. The strains were differentiated into nine and ten lactobacilli species by PCR and MALDI-TOF MS, respectively, with nine of these species being congruent. The success rates of species level assignment were 77% for PCR and 93% for MALDI-TOF MS that proved superior in the species identification. However, to differentiate between closely related Lactobacillus species, MALDI-TOF MS needs to be used in combination with genotypic techniques to achieve a more reliable identification.

LACTIC ACID BACTERIA AND THEIR ROLE IN THE MEAT PROCESSING

Lactic acid bacteria (LAB) play in meat processing a positive but also a negative role. The principal advantage of LAB in the production of dry fermented sausages lies in the fermentation of saccharides, i.e. the creation of lactic acid and the subsequent fall in pH. The role of LAB in fresh meat spoilage is still controversial. Several species are able to dominate the meat system in VP and MAP storage conditions and can release odor-impact molecules. On the other hand they can provide favorable antagonistic activity against other undesired microorganisms. LAB are important spoilage agents in cooked meat products. Аннотация Молочнокислые бактерии (МКБ) играют в мясной промышленности как положительную, так и отрицательную роль. Основная польза МКБ в производстве сухих ферментированных колбас заключается в ферментации сахаридов, т.е., образовании молочной кислоты и последующем падении рН. Роль МКБ в порче сырого мяса всё ещё неоднозначная. Несколько видов способны доминировать в мясной системе в условиях хранения в вакуумных упаковках и в модифицированной атмосфере и могут выделять молекулы, оказывающие влияние на запах. С другой стороны, они могут проявлять благоприятную антагонистическую активность против нежелательных микроорганизмов. МКБ являются важными возбудителями порчи в варёных мясопродуктах. DOI 10.21323/2114-441X-2016-1-25-31