Sugar and malic acid utilization and acetic acid formation byLeuconostoc oenos

Leuconostoc oenos ST8, isolated from an Argentinian red wine, utilized glucose, fructose and malic acid and produced acetic acid. Fructose was preferred to glucose as a source of carbohydrate. Malic acid was almost completely degraded in 3 days at 25°C. Acetic acid formation correlated with fructose utilization.     

Adduct formation of pyrroloquinoline quinone and amino acid

When pyrroloquinoline quinone (PQQ) is mixed with an amino acid, a corresponding Schiff base PQQ adduct is readily formed between carbonyl groups of PQQ and the primary amino group. A potent growth stimulating effect for microorganisms was observed with the PQQ adduct when it was administered in a culture medium. Although PQQ itself shows a marked growth stimulating effect, PQQ adducts appeared to be more active than authentic PQQ when compared on a molar basis. Conversely, unlike authentic PQQ, PQQ adducts were shown to be less active (greater than or equal to 100-fold) as the prosthetic group for a quinoprotein apo-glucose dehydrogenase when examined by holoenzyme formation by exogenous addition of PQQ or PQQ adducts. These observations suggested that PQQ adduct formation readily occurs during isolation procedures for PQQ from biological materials or PQQ - chromophore from quinoproteins. Therefore, the presence of such adducts gives a PQQ estimation much lower than theoretically expected. As an example, formation, isolation and characterization of PQQ - serine are described.