The cytoplasmic pyrophosphatase from Rhodobacter sphaeroides was purified and characterized. The enzyme is a homodimer of 64 kDa. The N-terminus was sequenced and used to obtain the complete pyrophosphatase sequence from the preliminary genome sequence of Rba. sphaeroides, showing extensive sequence similarity to family II or class C pyrophosphatases. The enzyme hydrolyzes only Mg-PP(i) and Mn-PP(i) with a K(m) of 0.35 mM for both substrates. It is not activated by free Mg (2+), in contrast to the cytoplasmic pyrophosphatase from Rhodospirillum rubrum, and it is not inhibited by NaF, methylendiphosphate, or imidodiphosphate. This work shows that Rba. sphaeroides and Rhodobacter capsulatus cytoplasmic pyrophosphatases belong to family II, in contrast to Rsp. rubrum, Rhodopseudomonas palustris, Rhodopseudomonas gelatinosa, and Rhodomicrobium vannielii cytoplasmic pyrophosphatases which should be classified as members of family I. This is the first report of family II cytoplasmic pyrophosphatases in photosynthetic bacteria and in a gram-negative organism.

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Lacid acid bactera LAB are used in the fermentation of milk for the production of various types od cheese, buttermilk and yougurts. The primary function of lactic acid bactera is the rapid fermentative conversion of lactose, the main sugar in milk, into lactic acid.It was shown that in Lactococcus genes involved in lactose transport and catabolism are plasmid-located. However, we observed that in plasmid cured, and therefore lactose-negative cells, cellobiose can induce lactose metabolism. Celiobiose belongs to a group of p-glucosides and it was demonstrated that Lactococcus lactis is able to grow on such sugars like arbutin, salicin, esculin and cellobiose and its growth is positively regulated through BglR protein a. Bardowski et al., 1994).