Progress in research of phosphorus budgets in aquaculture pond ecosystem and phosphate-solubilizing microorganisms
The present paper is aimed at introducing the up-to-date advances in the research of phosphorus budgets in aquaculture pond ecosystem and phosphate-solubilizing microorganisms. So far as we know, many studies have revealed that in the aquaculture ecosystem, the most important form of P output was the deposition of mud, however, the utilization rate of P was low. Therefore, if P fertilizers were applied regularly, it would be quickly fixed to unavailable forms and account for the low-level P application efficiency. Since great amount of phosphorus deposition in the sediment would increase not only the production cost, but also the increase of endogenous pollution. More specifically speaking, since phosphorus, the critical nutrient for pond aquaculture production, plays an important role in controlling the bio-organism productivity, it is necessary for the aquaculture ponds to properly apply phosphate fertilizer for the growth of phytoplankton. But, unfortunately, if too much P-fertilizer were put into the fish ponds, high P concentration sediment, in turn, would bring harms to the growth of aquaculture, as is seen in the deposition of mud. The reason is that the application of P solubilizing microorganisms (PSMs) tends to resolve the issues of the microorganisms to some extent. However, in natural environments, PSMs are on the whole considered to play an important ecophysiological role which helps to mobilize insoluble phosphate for the plants to grow. Furthermore, PSMs are most common in aquatic and terrestrial environment and influence the P recycling in somewhat direct and indirect ways. So far, quite a number of PSMs (such as Bacillus, Pseudomonas, Erwinia, Escherichia, Agrobacterium, Serratia, Penicillium, Aspergillus, Rhizopus, Streptomyces, et al) has been reported with PSMs isolated from the soil for the use of plant-growing promoters in the agriculture, though it is little reported in this way. In spite of this, lots of researches indicate that PSMs could be adapted to the aquatic environment, though PSMs may not be enough in natural ponds. For this need, it would be necessary or feasible to add some PSMs in such ponds. Therefore, while reviewing the P budget in the farming pond system, we have also systematically reviewed their P solubilization and the P solubilizing mechanisms of PSMs.