Say Cheese! Scientists In A Ferment Over Cheese-Starter Genome

Daily Science Journal (Jun. 19, 2007) — Whether sharp Cheddar or nutty Gouda, a fine cheese owes its flavor to milk-fermenting bacteria, such as the historically ancient starter Lactococcus lactis. In next month’s issue of Genome Research, researchers from France report the complete genome sequence of L. lactis, now the most commonly used starter in the cheese industry.

L. lactis is a member of the lactic acid bacteria (LAB) family, which includes not only cheese and yogurt starters, but also pathogens like Streptococcus pneumoniae. Until now, none of the LAB genomes have been sequenced. To produce the L. lactis sequence, Alexei Sorokin and colleagues from Génoscope and the Institut National de la Recherche Agronomique have used a novel approach that reduces the number of steps for obtaining a complete bacterial genome sequence.

Now the researchers report the entire L. lactis sequence of 2.4 million nucleotides, which encode 2310 genes (363 specific for lactococci). In their analysis of the genome, the researchers made several surprising discoveries, including genes suggesting this fermentative bacterium can perform aerobic respiration. This research marks a critical step towards understanding and manipulating the LAB and, in particular, will be useful for improving the flavor, texture, and preservation of10 million tons of cheese produced annually. Now that's a lot of cheese.

Adapted from materials provided by Cold Spring Harbor Laboratory.