Behavior and proteome differentiation of Lactobacillus sakei 23k, a meat borne lactobacilli, during its growth in presence of meat proteins

SILVINA FADDA; ELVIRA HÉBERT; FABIENNEBARAIGE; PATRICIA ANGLADE; MONIQUE ZAGOREC; RÉGINE TALON; GRACIELA VIGNOLO; MARIE CHRISTINE CHAMPOMIER-VERGÈS

Buenos Aires, Argentina

Congreso; LAHUPO 1st Annual Iberoamerican Proteomics Congress; 2007

Latinoamerican Human Proteome Organization

Lactobacillus sakei is a lactic acid bacterium belonging to the natural flora of fresh and vacuum-packed meat, used as starter for manufacturing fermented sausages. In order to understand strategies of this bacterium for adaptation to meat environment, a proteomic approach was undertaken. The behavior of this strain when growing in a chemically defined medium (CDM) containing sarcoplasmic or myofbrillar proteins at 30ºC during 72h was investigated. Bidimensional electrophoresis profiles showed at least 15 and 6 proteins differentially expressed in presence of myofibrillar and sarcoplasmic proteins, respectively, when compared to the control. According to MALDITOF-MS analyses, proteins involved in purines/pyrimidines, amino acids, vitamins/cofactors biosynthesis and stress responses were under expressed in presence of both protein types. This behavior could be related to the additional nutrient source furnished by meat extracts which allow cells do not expend energy to synthesize cofactors, vitamins or amino acids already supplied. In presence of sarcoplasmic proteins L. sakei 23K proteome presented an increased expression of three proteins related to peptide degradation and translation (pepD5_lsa0897; pepD2_ lsa0196; rpsA_ lsa1017). While when myofibrillar proteins were added, microbial proteome over expressed 5 different proteins related to energy metabolism and translation (alaS_lsa0387; rpiA_lsa1685; pfk_lsa1033). These up regulated proteins are in parallel with the supplementary nutrients supplied by both meat extracts, mainly amino acids, nucleotides and cofactors which could induce translation, amino acid metabolism and energy production. Finally, SDS-PAGE analyses were carried out to investigate cell lysis during incubation. No cell disruption was observed on supernatant media, only meat proteins were present, except in the control. Even though, on myofibrillar proteins, slight protein hydrolysis were recorded at 72h and also observed in absence of bacterial inoculation indicating some endogen proteolysis or increased protein solubility throughout the time. This study is a preliminary description of the proteins involved on meat adaptation. Bidimensional electrophoresis constitutes a useful tool to evaluate bacterial behavior and adaptation to different matrix.