Inorganic phosphorus is one of the critical nutrients determining trophic state and freshwater productivity. Sediment may act as a sink or source of phosphorus to the overlying water depending on its pH, redox state, various forms of phosphorus present, etc. To examine potential sorption or mobilization of sediment phosphorus in floodplain wetlands, the amount and distribution of phosphorus fractions were evaluated using a sequential chemical extraction procedure. Exceedingly high levels of total phosphorus (mean: 6040 § 344, 5470 § 363 mg kg ¡1 ), consisting largely of organic and refractory fraction (70 -98%), followed by calcium-phosphorus (mean: 584 § 31.3, 143 § 8.42 mg kg ¡1 ) and iron-phosphorus (mean: 108 § 10.1, 91.0 § 7.68 mg kg ¡1 ) were recorded respectively in Bhomra and Akaipur wetlands of West Bengal, India. The inorganic phosphorus, comprising the loosely sorbed phosphorus and all the mineral bound forms contributed only about 6-14% to the total phosphorus indicating their less significance in phosphorus sorption or desorption in these tropical wetlands. Although the loosely sorbed phosphorus was in moderate level (2.69 § 0.69, 1.54 § 0.53 mg kg ¡1 ), water dissolved phosphorus was recorded at higher concentrations (mean: 0.16 § 0.02 mg l ¡1 in Akaipur and 1.08 § 0.12 mg l ¡1 in Bhomra). However, the higher level of water available phosphorus was not reflected in plankton production since the dominance of weeds suppresses their growth. This study recorded large accumulation of organic matter and nutrients in the form of detritus in these wetlands which may be channelized for fish production through stocking of suitable detritivorous fishes and/or reducing macrophyte coverage that would give space and nutrients for phytoplankton growth.
Microbial mobilization of sediment calcium-bound P constitutes an important process of P cycling in aquatic environments. The present study was conducted to identify the bacterial community responsible for inorganic phosphate solubilization in tropical oxbow lakes. Fifty eight phosphate solubilizing bacteria were isolated from bottom soil, water, and fish gut and examined for solubilization of tricalcium phosphate. Results revealed aquatic PSB to be low to moderately capable in P solubilization (mean: 33.5 mg P l -1 ; range: 6.3-68.8 mg P l -1 ), and bacteria from wetland sediment and water were more effective than those from fish gut. The PSB were identified to belong to diverse genera, viz. Bacillus, Brevibacillus, Enterobacter, Agrobacterium, Pseudomonas, Acinetobacter, Microbacterium, Curtobacterium, Stenotrophomonas and Novosphingobium. The findings would help in understanding the microbial role in inorganic P solubilization and identifying important P solubilizers in freshwater environments.
Bacillus sp. strain CPSM8 is an efficient solubilizer and mineralizer of phosphorus. Here, we present the 4.39-Mb draft genome sequence of the strain, providing insight into the phosphorus-releasing genes related to productivity in aquatic habitats.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.