Reference

Gas chromatography and gateway sensors for on-line state estimation of complex fermentations (butanol-acetone fermentation)

Gas chromatography and gateway sensors for on-line state estimation of complex fermentations (butanol-acetone fermentation). McLaughlin, Joseph K.; Meyer, Charles L.; Papoutsakis, Eleftherios T. (Dep. Chem. Eng., Rice Univ., Houston, TX 77251, USA). Biotechnol. Bioeng., 27(8), 1246-57 (English) 1985. CODEN: BIBIAU. ISSN: 0006-3592. DOCUMENT TYPE: Journal CA Section: 16 (Fermentation and Bioindustrial Chemistry) A fermn. system was designed to demonstrate the use of gas chromatog. (GC) for on-line monitoring of the BuOH [35296-72-1]-acetone [67-64-1] and other complex saccharolytic fermns. Tangential flow ultrafiltration was used to sterilely and continuously obtain a cell-free filtrate from the fermn. broth for on-line gas chromatog. anal. of BuOH, butyrate [107-92-6], acetate [64-19-7], acetone, EtOH [64-17-5], and acetoin [513-86-0]. The liq. injection system consists of a H3PO4 contactor, a slider-type injection valve, and a heater to address the difficulties (ghosting) encountered in the anal. of carboxylic acids. The fermentor headspace gas was also analyzed by on-line gas chromatog. for N2 and CO2, while H2 was measured by difference. Raw chromatog. data were analyzed by a chromatog. data system. Both raw and processed data were transmitted to a VAX 11/750 computer for further processing (using the fermn. equation) and archiving. The fermn. equation, which was recently derived and tested on completed fermn. data, was also valid during transient fermns. and thus useful as a gateway sensor for calcg. various fermn. parameters on-line. Such parameters include glucose concn. and gas compn., as well as a no. of unobservable parameters which characterize the state of the fermn.

Transformation of citric acid to acetic acid, acetoin and diacetyl by wine making lactic acid bacteria

Transformation of citric acid to acetic acid, acetoin and diacetyl by wine making lactic acid bacteria. Shimazu, Yoshimi; Uehara, Mikio; Watanabe, Masazumi (Food Res. Lab., Kikkoman Corp., Noda 278, Japan). Agric. Biol. Chem., 49(7), 2147-57 (English) 1985. CODEN: ABCHA6. ISSN: 0002-1369. DOCUMENT TYPE: Journal CA Section: 16 (Fermentation and Bioindustrial Chemistry) A decrease in citric acid [77-92-9] and increases in HOAc [64-19-7], acetoin [513-86-0], and diacetyl [431-03-8] were found in red wine and synthetic solns. after inoculation of intact cells of Leuconostoc mesenteroides lactosum. It was concluded that citric acid in wine involving malolactic fermn. is first converted by citrate lyase [9012-83-3] to HOAc and oxaloacetic acid [328-42-7], and the latter was transformed by decarboxylation to pyruvic acid [127-17-3] which was subsequently coverted to acetoin, diacetyl, and HOAc. Both the activities of citrate lyase and acetoin formation from pyruvic acid in the dialyzed cell-free ext. were optimal at pH 6.0. Divalent cations activated citrate lyase. Citrate lyase was completely inhibited by EDTA, Hg2+ and Ag2+. Acetoin formation from pyruvic acid was significantly stimulated by thiamin pyrophosphate and CoCl2 and inhibited by oxaloacetic acid. Specific activities of citrate lyase and acetoin formation varied considerably among the 6 strains of malolactic bacteria examd. Some irreversible redn. of diacetyl to acetoin were found in cell-free exts. of 4 of the malolactic bacteria; the optimal pH was 6.0 for this activity in L. mesenteroides.