Technological properties and bacteriocins production by Lactobacillus curvatus 54M16 and its use as starter culture for fermented sausage manufacture

Lactobacillus curvatus 54M16 was isolated from traditional fermented sausages of Campania region (Italy) and identified by 16S rRNA and hsp60 gene sequencing and by SDS-PAGE of whole cell proteins. The strain produced more than one bacteriocin, carrying the genes for sakacin X, T and P as demonstrated by PCR studies. The ability of L. curvatus 54M16 to produce multiple bacteriocins is confirmed by molecular mass spectrometry analysis and N-terminal amino acid sequencing. Among the bacteria tested, the pathogens Listeria monocytogenes and Bacillus cereus and the meat spoilage Brochotrix thermosphacta were sensitive to the bacteriocins. No inhibition of tested Gram-negative bacteria, some strains of Lactobacillus and of strains of Staphylococcus aureus was observed. All the in vitro conditions tested for the production of the bacteriocins (temperature, pH and NaCl), indicate that the strain of L. curvatus 54M16 is able to grow and to produce the antagonistic substances at pH 4.5 and in the presence of 4% NaCl. The strain has good acidifier capability and it is able to hydrolyse sarcoplasmic but not myofibrillar proteins, lipids and to reduce nitrates. Moreover it shown high values of SOD, while the aminopeptidase activity is restricted to whole cells that hydrolyse at high rates the amino acids l-arginine, l-valine, l-phenylalanine and l-lysine. The suitability of L. curvatus 54M16 as starter culture was assayed during sausage fermentation. Its use can improve the quality and safety of the traditional fermented sausages prepared without antimicrobial additives.