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Although not rigorously studied, it has long appeared that bacteria are unique in their ability to metabolize those organic materials which are rarely, if ever, found in nature. Aerobacter aerogenes, PRL R3, particularly illustrates this phenomenon with its ability to utilize as a source of energy seven of the eight aldopentoses and all four of the pentitols.' 2 Of this group of 11 structures, D-ribose, D-xylose, Larabinose, D-arabitol, and ribitol are found in nature, whereas D-arabinose, Dlyxose, L-xylose, L-lyxose, xylitol, and L-arabitol3 seem to be rarely, if ever, encountered in the natural environment.4 The routes of utilization of all of these C, compounds have been documented (Fig. 1).2. [5][6][7][8][9][10][11][12][13][14][15][16][17][18] Referring to Figure 1, it can be seen that metabolism of the unnatural compounds, D-lyxose and xylitol, for example, involves only one new or unique reaction for each, i.e., isomerization of D-lyxose or oxidation of xylitol to D-xylulose. The phosphorylation of D-xylulose is common to the route for utilization of D-xylose and D-arabitol, both naturally occurring substrates readily attacked by A. aerogenes. Similarly, the conversions of L-xylose, L-lyxose, and L-arabitol involve either isomerizations or an oxidation to L-xylulose.2 8 The subsequent reactions of the pathway are common to those for L-xylulose and L-ribulose2 19 which appear in nature as metabolic intermediates in utilization of L-ascorbate20 and L-arabi-*

Tea fungus/kombucha, an acetic acid flavoured fermented tea beverage, is widely consumed in various parts of the world and has more recently become a fad in the United States. This is due in part to the fact that it can be produced in the home, and it is reported to be medicinal, effective against arthritis, psoriasis, chronic fatigue, constipation, indigestion and metabolic diseases. Among 264 references from 1852 to 1961, there are reports of.antibiotic activity against Agrobacterium tumefaciens and medicinal value against a variety of diseases. The medicinal value appears to be related to that attributed to vinegar, one of our most ancient foods. We decided to test tea fungus/ kombucha for its antibiotic activity against Helicobacter pylori, a primary cause of gastritis related to peptic ulcers and gastric carcinoma, Escherichia coli, Staphylococcus (Micrococcus) aureus and Agrobacterium tumefaciens. Tea containing 4.36 g of dry tea per litre and 10% of sucrose and fermented with the tea fungus showed no antibiotic activity in the beverage beyond that caused by acetic acid, a primary product of the fermentation.

Several growth characteristics of Escherichia coli K-12 suggest that growth on l -fucose results in the synthesis of all the enzymes necessary for growth on d -arabinose. Conversely, when a mutant of E. coli is grown on d -arabinose, all of the enzymes necessary for immediate growth on l -fucose are present. Three enzymes of the l -fucose pathway in E. coli , l -fucose isomerase, l -fuculokinase, and l -fuculose-l-phospháte aldolase possess activity on d -arabinose, d -ribulose, and d -ribulose-l-phosphate, respectively. The products of the aldolase, with d -ribulose-l-phosphate as substrate, are dihydroxyacetone phosphate and glycolaldehyde. l -Fucose, but not d -arabinose, is capable of inducing these activities in wild-type E. coli . In mutants capable of utilizing d -arabinose as sole source of carbon and energy, these activities are induced in the presence of d -arabinose and in the presence of l -fucose. Mutants unable to utilize l -fucose, selected from strains capable of growth on d -arabinose, are found to have lost the ability to grow on d -arabinose. Enzymatic analysis of cell-free extracts, prepared from cultures of these mutants, reveals that a deficiency in any of the l -fucose pathway enzymes results in the loss of ability to utilize d -arabinose. Thus, the pathway of d -arabinose catabolism in E. coli K-12 is believed to be: d -arabinose ⇌ d -ribulose → d -ribulose-l-phosphate ⇌ dihydroxyacetone phosphate plus glycolaldehyde. Evidence is presented which suggests that the glycolaldehyde is further oxidized to glycolate.

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