Aquatic eutrophication and bloom of toxic algae triggered by release of phosphorus in wastewater have been recognized as environmental problems. The enhanced biological phosphate removal (EBPR) has widely utilized for removing phosphorus from wastewater and preventing phosphorus from diffusing into environment. Polyphosphate accumulating organisms (PAOs) are frequently found in activated sludge in the EBPR process, and believed to play a pivotal role in phosphorus removal. PAOs are microorganisms which take up phosphate into the cells and accumulate it as the form of polyphosphate (polyP) under aerobic conditions. In additions to polyP accumulation, PAOs are supposed to synthesize polyhydroxyalkanoates (PHAs), known as a source of bioplastics. Therefore, PAOs have received industrial attention for their possible use in phosphorus recycling and supply of biodegrative plastics.
Microlunatus phosphovorus NM-1T is an actinobacterium isolated from EBPR activated sludge, as one of rare examples isolated successfully from such an environment. M. phosphovorus NM-1T represents competent features as PAOs; it can accumulate polyP more than 10% of cell mass as phosphorus on a dry weight basis. In addition, a recent study using PHA staining and gas chromatography suggested the presence of PHAs in cells of M. phosphovorus.
The genome of M. phosphovorus NM-1T consisted of a single circular chromosome (5,683,123 bp; G+C content of 67.3%) containing 5,359 predicted protein-coding genes. The M. phosphovorus genome possessed a larger number of genes related to polyP accumulation than other related microorganisms. On the other hand, the homologous genes which are involved in PHA synthesis in proteobacterial PAOs were not observed in M. phosphovorus, suggesting that the organism possibly contains an unknown PHA biosynthetic pathway. Minute analysis of this genome will give useful information and a new insight to investigation about biological mechanisms of polyP accumulation and production of bioplastics.
|Genomic size||5,683,123 bp|
|G+C content||67.27 %|
|Number of ORFs assigned||5,359|
|Percentage of the coding regions||90.59 %|
|Percentage of the intronic regions||0.00 %|
|Number of rRNA genes||
|Number of tRNA genes||
|Number of other features
The nucleotide sequence of the M. phosphovorus NM-1T (= NBRC 101784T) genome was determined by the whole genome shotgun sequencing method as in the case of other organisms analyzed at NITE-DOB.