Research advances of Tetrasphaera in enhanced biological phosphorus removal: A review.

The processes of enhanced biological phosphorus removal (EBPR) have been widely applied in wastewater treatment plants (WWTPs). However, meeting the increasingly stringent effluent discharge standards requires a more stable EBPR performance. Under the circumstances, the identification of genus Tetrasphaera as potential phosphate accumulating organisms (PAOs) has aroused much research interests on them. In practice, a large biovolume of genus Tetrasphaera has been reliably observed in a number (up to 80) of WWTPs around the world. Tetrasphaera show a phenotype of aerobic polyphosphate (poly-P) accumulation at the condition of assimilating glucose and/or amino acids anaerobically in advance. Moreover, Tetrasphaera also present versatile physiologies, of which some show no net orthophosphate removal. While there are certainly some contradictory results and gaps in our knowledge concerning Tetrasphaera, this review summarizes the discovery, abundance in WWTPs, functions on EBPR, and biochemistry of the genus Tetrasphaera in the existing literature. It is expected to present the state-of-art progress about the genus Tetrasphaera, and to guide future R & D work.

Physiological features of Halomonas lionensis sp. nov., a novel bacterium isolated from a Mediterranean Sea sediment.

A novel halophilic bacterium, strain RHS90(T), was isolated from marine sediments from the Gulf of Lions, in the Mediterranean Sea. Its metabolic and physiological characteristics were examined under various cultural conditions, including exposure to stressful ones (oligotrophy, high pressure and high concentrations of metals). Based on phylogenetic analysis of the 16S rRNA gene, the strain was found to belong to the genus Halomonas in the class Gammaproteobacteria. Its closest relatives are Halomonas axialensis and Halomonas meridiana (98% similarity). DNA-DNA hybridizations indicated that the novel isolate is genotypically distinct from these species. The DNA G + C content of the strain is 54.4 mol%. The main fatty acids (C18:1ω7c, 2-OH iso-C15:0, C16:0 and/or C19:0 cyclo ω8c), main polar lipids (diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine and an unidentified phosphoglycolipid) and major respiratory quinone (ubiquinone Q9) were determined. The novel isolate is heterotrophic, mesophilic, euryhaline (growth optimum ranging from 2 to 8% w/v NaCl) and is able to grow under stressful conditions. The strain accumulates poly-ß-hydroxyalkanoates granules and compatible solutes. Based on genotypic, chemotaxonomic and phenotypic distinctiveness, this isolate is likely to represent a novel species, for which the name Halomonas lionensis is proposed. The type strain of H. lionensis is RHS90(T) (DSM 25632(T) = CIP 110370(T) = UBOCC 3186(T)).