Investigation for functionalities of rhizo-biocomplex to minimize highly adverse conditions in association with organic sink in the rhizosphere and its utilization in agricultural use

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We investigated rhizo-biosystems that enable to mitigate adverse soils in Kalimantan, Indonesia. Burkholderia sp. strain A-KA that had been isolated from the rhizosphere of Imperata cylindrica grown in medium-strongly acidic peatland showed a growth-helper activity toward other rhizosphere bacteria, such as Sphingomonas sp. Burkholderia mimosarum isolated from rhizosphere of paddy rice tolerant to acid-sulfate soil suppressed tropolone production of B. plantarii, a bacterium causative of rice blight disease, while promoted growth of diverse root-and seed-epiphytic bacteria. Among rhizobacteria that had isolated from dipterocarpous sapling adapting to polyphenol-rich tropical peat soil, pyrogallol-containing plant polyphenols activated Burkholderia unamae CK-43B to degrade indole and some other N-heterocyclic aromatic compounds. In the coralloid root symbiotic systems between Cycas revoluta root and a nitrogen-fixing cyanobacterium Nostoc punchiforme, a diacylglycerol was found to be the principle of hormogoniu-inducing factor on the cyanobacterium necessary to its host-recognition. Also, we successfully isolated and characterized signal compounds from a rhizobacterium Pseudomonas jessenii strain EC-S101 isolated from spinach root and from a rhizosphere fungus Trichoderma virens strain PS1-7 isolated from paddy root. In the rhizosphere, nitrous oxide emitting bacteria in tropical peat soil were missing their nitrous oxide reductase (N2OR) genes, and affected its denitrification by several secondary metabolites of plants