Simultaneous Nitrogen Removal and Plant Growth Promotion Using Salt-‍tolerant Denitrifying Bacteria in Agricultural Wastewater

Abstract

Excess nitrate (NO 3 -) and nitrite (NO 2 -) in surface waters adversely affect human and environmental health. Bacteria with the ability to remove nitrogen (N) have been isolated to reduce water pollution caused by the excessive use of N fertilizer. To obtain plant growth-promoting rhizobacteria (PGPR) with salt tolerance and NO 3 --N removal abilities, bacterial strains were isolated from plant rhizosphere soils, their plant growth-promoting effects were evaluated using tomato in plate assays, and their NO 3 --N removal abilities were tested under different salinity, initial pH, carbon source, and agriculture wastewater conditions. The results obtained showed that among the seven strains examined, five significantly increased the dry weight of tomato plants. Two strains, Pseudomonas stutzeri NRCB010 and Bacillus velezensis NRCB026, showed good plant growth-promoting effects, salinity resistance, and NO 3 --N removal abilities. The maximum NO 3 --N removal rates from denitrifying medium were recorded by NRCB010 (90.6%) and NRCB026 (92.0%) at pH 7.0. Higher NO 3 --N removal rates were achieved using glucose or glycerin as the sole carbon source. The total N (TN) removal rates of NRCB010 and NRCB026 were 90.6 and 66.7% in farmland effluents, respectively, and 79.9 and 81.6% in aquaculture water, respectively. These results demonstrate the potential of NRCB010 and NRCB026 in the development of novel biofertilizers and their use in reducing N pollution in water.

Certain Tomato Root Exudates Induced by Pseudomonas stutzeri NRCB010 Enhance Its Rhizosphere Colonization Capability

“…Colonization ability was measured as previously described [ 21 ] with minor modifications. Briefly, the diluted NRCB010 fermentation was centrifuged at 6500× g for 5 min and resuspended in a 10-time volume of 0.86% ( w / v ) NaCl.…”

“…In summary, PGPR change the root exudate metabolite profile; conversely, root exudate metabolites regulate the colonization, chemotaxis, and biofilm formation of PGPR, which optimizes PGPR survival and function. P. stutzeri NRCB010 (NRCB010) was previously isolated from a rice rhizosphere soil [ 21 ]. For further development and utilization of NRCB010, the interactions between NRCB010 and host plants, that is, the effects of NRCB010 on tomato root exudate metabolite profiles and the subsequent effects of root exudate metabolites on NRCB010 biomass, colonization, chemotaxis, and biofilm formation, were investigated.…”

The Whole Genome Sequence of Pseudomonas fernandeno sp. nov. from Soil and the Agricultural Discovery Pipeline

“…Bacteria decompose organic matter and deceased organisms, breaking them down to make nutrients available to plants as well as many other important functions (Zhang 2022). Some of these other functions are Nitrogen cycling, protecting plants against harmful pathogens, and improving the soil aeration.…”

A Study of Purification in Pine Forest Soils after Salt Damage from the Tsunami in Enjugahama Beach, Wakayama Prefecture

“…Rainfall and irrigation can wash surface salts away from drainage channels. Thus, stripping saline topsoil is considered an effective salt removal measure that farmers can implement [9,11,12]. The principle is to remove salt from the soil through repeated dilution and permeation of the salt [13].…”