Esterase activities of intracellular extracts of wild strains of lactic acid bacteria isolated from Serra da Estrela cheese

Lactococcus lactis subsp. lactis strain ESB110019 and Lactobacillus plantarum strain ESB5004, novel strains that were previously isolated from the wild adventitious microflora of certified Serra da Estrela cheeses, were assayed for esterase activity using, as substrates, ortho- and para-nitrophenyl derivatives of fatty acids. Both strains preferentially hydrolyzed short-chain fatty acids; L. lactis ESB110019 exhibited a stronger esterase activity than Lb. plantarum ESB5004 and cleaved the p-nitrophenyl adducts faster than their o-nitrophenyl counterparts (unlike Lb. plantarum ESB5004).