Hydrogen and organic acid production from dark fermentation of cheese whey without buffers under mesophilic condition

There are three main reasons for using lactic acid bacteria (LAB) as starter cultures in industrial food fermentation processes: food preservation due to lactic acid production; flavour formation due to a range of organic molecules derived from sugar, lipid and protein catabolism; and probiotic properties attributed to some strains of LAB, mainly of lactobacilli. The aim of this study was to identify some genes involved in lactose metabolism of the probiotic Lactobacillus delbrueckii UFV H2b20, and analyse its organic acid production during growth in skimmed milk. The following genes were identified, encoding the respective enzymes: ldh – lactate dehydrogenase, adhE – Ldb1707 acetaldehyde dehydrogenase, and ccpA-pepR1 – catabolite control protein A. It was observed that L. delbrueckii UFV H2b20 cultivated in different media has the unexpected ability to catabolyse galactose, and to produce high amounts of succinic acid, which was absent in the beginning, raising doubts about the subspecies in question. The phylogenetic analyses showed that this strain can be compared physiologically to L. delbrueckii subsp. bulgaricus and L. delbrueckii subsp. lactis, which are able to degrade lactose and can grow in milk. L. delbrueckii UFV H2b20 sequences have grouped with L. delbrueckii subsp. bulgaricus ATCC 11842 and L. delbrueckii subsp. bulgaricus ATCC BAA-365, strengthening the classification of this probiotic strain in the NCFM group proposed by a previous study. Additionally, L. delbrueckii UFV H2b20 presented an evolutionary pattern closer to that of probiotic Lactobacillus acidophilus NCFM, corroborating the suggestion that this strain might be considered as a new and unusual subspecies among L. delbrueckii subspecies, the first one identified as a probiotic. In addition, its unusual ability to metabolise galactose, which was significantly consumed in the fermentation medium, might be exploited to produce low-browning probiotic Mozzarella cheeses, a desirable property for pizza cheeses.

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Part III. The Respiratory Regulation in Psychotic Subjects

Journal of Mental Science ◽

10.1192/bjp.74.306.443 ◽

1928 ◽

Vol 74 (306) ◽

pp. 443-453 ◽

Cited By ~ 18

Author(s):

F. Golla ◽

S. A. Mann ◽

F. Golla ◽

R. G. B. Marsh

Keyword(s):

Organic Acid ◽

Acid Production ◽

Normal Subjects ◽

Compensatory Mechanism ◽

Acid Base ◽

Organic Acid Production ◽

Respiratory Regulation ◽

Acid Base Equilibrium ◽

Buffering Power ◽

Respiratory Centre

The preceding studies on the acid-base equilibrium in psychotics have made it evident that the failure to adjust must be attributed in the first instance to an inadequacy of the respiratory compensatory mechanism, and can be in no sense attributable to either a deficiency in the buffering power of the blood itself or to an increased organic acid production (acidosis). We have endeavoured to determine the excitability of the respiratory centre to the stimulus created by CO2. For this purpose a number of psychotic patients were tested as to the excitability of the respiratory centre to air containing 2% CO2 and the reaction compared with that obtaining in a number of normal subjects.

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