1. A comparison of rates of oxidation of various compounds by whole cells indicated that protocatechuate was a reaction intermediate when a non-fluorescent species of Pseudomonas oxidized p-cresol. In contrast, a fluorescent Pseudomonas oxidized 3-methylcatechol and 4-methylcatechol when grown with p-cresol, but did not oxidize protocatechuate. 2. Heat-treated extracts of the fluorescent Pseudomonas oxidized catechol, 3-methylcatechol and 4-methylcatechol to ring-fission products, the spectroscopic properties of which were recorded. Rates of enzymic degradation of these products were also measured. 3. Acetic acid and formic acid were obtained by the action of a Sephadex-treated extract on 3-methylcatechol and 4-methylcatechol respectively. In each case 0.8mol. of the carboxylic acid was formed from 1.0mol. of substrate. 4. Dialysed extracts converted 3-methylcatechol into acetaldehyde and pyruvate, with 4-hydroxy-2-oxovalerate as a reaction intermediate. 4-Methylcatechol was converted first into 4-hydroxy-2-oxohexanoate and then into propionaldehyde and pyruvate. 5. The ring-fission product of catechol was formed from phenol by a fluorescent Pseudomonas, that of 3-methylcatechol was formed from o-cresol and m-cresol, and the ring-fission product of 4-methylcatechol was given from p-cresol. Propionate was readily oxidized by these cells after growth with p-cresol, but this compound was not attacked when phenol, o-cresol or m-cresol served as source of carbon. 6. Cell extracts appeared to attack only one enantiomer of synthetic 4-hydroxy-2-oxohexanoate.

All activated sludge systems for removing phosphate microbiologically are configured so the biomass is cycled continuously through alternating anaerobic and aerobic zones. This paper describes a novel aerobic process capable of decreasing the amount of phosphate from 10 to 12 mg P liter ؊1 to less than 0.1 mg P liter ؊1(when expressed as phosphorus) over an extended period from two wastewaters with low chemical oxygen demand. One wastewater was synthetic, and the other was a clarified effluent from a conventional activated sludge system. Unlike anaerobic/aerobic enhanced biological phosphate removal (EBPR) processes where the organic substrates and the phosphate are supplied simultaneously to the biomass under anaerobic conditions, in this aerobic process, the addition of acetate, which begins the feed stage, is temporally separated from the addition of phosphate, which begins the famine stage. Conditions for establishing this process in a sequencing batch reactor are detailed, together with a description of the changes in poly-␤-hydroxyalkanoate (PHA) and poly(P) levels in the biomass occurring under the feed and famine regimes, which closely resemble those reported in anaerobic/aerobic EBPR processes. Profiles obtained with denaturing gradient gel electrophoresis were very similar for communities fed both wastewaters, and once established, these communities remained stable over prolonged periods of time. 16S rRNA-based clone libraries generated from the two communities were also very similar. Fluorescence in situ hybridization (FISH)/microautoradiography and histochemical staining revealed that "Candidatus Accumulibacter phosphatis" bacteria were the dominant poly(P)-accumulating organisms (PAO) in both communities, with the phenotype expected for PAO. FISH also identified large numbers of betaproteobacterial Dechloromonas and alphaproteobacterial tetrad-forming organisms related to Defluviicoccus in both communities, but while these organisms assimilated acetate and contained intracellular PHA during the feed stages, they never accumulated poly(P) during the cycles, consistent with the phenotype of glycogen-accumulating organisms.High levels of phosphate in effluents from activated sludge systems not designed to remove it can lead to toxic cyanobacterial blooms in receiving bodies of water. Consequently, efforts have been directed towards removing phosphate during treatment by microbiological means with a process called enhanced biological phosphorus removal (EBPR), where phosphate is removed from the wasted biomass as intracellular poly(P) (5, 37, 45). Such treatment processes are based on the underlying principle that the biomass needs to be recycled repeatedly through alternating anaerobic and aerobic stages (37), a requirement regarded as crucial for successful EBPR operation. Only after repeated recycling are poly(P)-accumulating organisms (PAO) thought to have a selective advantage over other populations, eventually allowing them to become dominant (5,37,45). In the anaerobic (feed) stage, PAO are belie...

1. Partially purified extracts of a Pseudomonas converted the meta ring-fission product of 4-methylcatechol into a compound having spectroscopic and chemical properties consistent with its being 2-oxohex-4-enoic acid. 2. Catechol and 3-methylcatechol were both metabolized to a compound that appeared to be 2-oxopent-4-enoic acid. 3. Solutions of norvaline and norleucine were prepared from these metabolites. 4. A reaction scheme is presented for the conversion of catechols into hydroxyoxo acids after meta ring-fission.