Quantitative studies on phosphorus transference occuring between Microcystis aeruginosa and its attached bacterium (Pseudomonas sp.)

Abstract

Phosphorus release from Microcystis aeruginosa and attached bacterium (Pseudomonas sp.) isolated from Lake Taihu was examined using a phosphorus isotope tracer in order to investigate the phosphorus transference between the two species. Our results reveal that the amount of phosphorus released form 32 P-saturated M. aeruginosa is determined by its growth phase and most of phosphorus is assimilated by Pseudomonas finally while the amount of phosphorus released from 32 P-saturated Pseudomonas is also determined by the growth phase of M. aeruginosa and most of them are assimilated by M. aeruginosa. The results suggest that phosphorus transference occurs between M. aeruginosa and its attached Pseudomonas . This process makes microenvironment of mucilage of M. aeruginosa attached bacteria maintain relative high amounts of phosphorus. Attached bacteria may be a temporary phosphorus bank to the growth of M. aeruginosa, and assimilation of phosphorus by M. aeruginosa becomes easy when M. aeruginosa is in lag growth phase. Thus, the phosphorus exchange between M. aeruginosa and attached Pseudomonas in microenvironment may be important to microfood web and cyanobacteria bloom.

Specific association between bacteria and buoyant Microcystis colonies compared with other bulk bacterial communities in the eutrophic Lake Taihu, China

“…Heterotrophic bacterial growth is enhanced by extracellular polysaccharide secretion from Microcystis aeruginosa (Shen et al ., ). Phosphorus cycling between the colonial cyanobacterium, M. aeruginosa , and attached bacteria, such as Pseudomonas , was reported (Jiang et al ., ). These preceding observations suggest a close relationship between Microcystis and the associated bacteria.…”

Culture-independent and culture-dependent analyses of the bacterial community in the phycosphere of cyanobloom-forming Microcystis aeruginosa

“…Microcystis species grow into large mucilaginous aggregates, which comprise a microscale mucus region called the phycosphere, and this region is generally colonized by associated bacteria 19 . Fluctuations in the bacterial diversity associated with Microcystis- blooms are often observed in many environmental samples 20 .…”

Phosphorus cycling between the colonial cyanobacterium Microcystis aeruginosa and attached bacteria, Pseudomonas

“…In another recent study using dialysis bags, we observed that P is transferred from Pseudomonas to M. aeruginosa when M. aeruginosa is in growth phase, while P transfer from M. aeruginosa to Pseudomonas occurs when M. aeruginosa is in decline phase (Jiang et al 2007). Although these results are both sensitive and highly repeatable, it is difficult to extrapolate these results to explain the field observation in which Microcystis spp.…”

“…The green fluorescence protein (gfp)-labeled attached bacterium Pseudomonas was acquired by transforming a plasmid (pJZ383, containing the gfp gene) into Pseudomonas, which was isolated from the mucilage of Microcystis in Lake Taihu, China (Jiang et al 2007). We chose the gfp-labeled clones and tested their growth stability by comparing the biomass with unlabeled clones in parallel cultures every 12 h for 3 days, then selected the optimal clone.…”

“…Pseudomonas was grown in a medium comprising 6.0 g glucose, 1.0 g NH 4 Cl, 2.0 g NaCl, 0.2 g MgSO 4 7H 2 O, 1.0 g K 2 HPO 4 , 1.0 g KH 2 PO 4 , and 0.5 g yeast extract in 1 l of deionized water. The pH of the medium was adjusted to 7.2-7.5 before autoclaving at 112°C for 20 min (Jiang et al 2007). …”