Selection of Acid-Resistant Purple Nonsulfur Bacteria from Peat Swamp Forests to Apply as Biofertilizers and Biocontrol Agents

Abstract

This study aimed to investigate an inexpensive enrichment medium for obtaining acid-resistant purple nonsulfur bacteria (PNSB) from peat swamp forests (PSF), screening PNSB for their biofertilizer and biocontrol properties, and investigating physicochemical properties of PSF. Rice straw and G5 broths were used to count PNSB in PSF of Southern Thailand, and isolated PNSB were selected based on the release of nutrients (NH 4 + and PO 4 3− from various P-sources), plant growth-promoting substances (PGPS-siderophores, exopolymeric substances, indole-3-acetic acid, and 5-aminolevulinic acid), and inhibiting rice fungal pathogens (Bipolaris oryzae NPT0508 and Curvularia lunata SPB0627). Soil and water samples from primary and secondary PSF of Kan Tulee showed significant differences only for pH in soil and SO 4 2− in water. Almost parameters of both sample types from Kuan Kreng secondary PSF were higher than for Kan Tulee site, except pH. PNSB population was low in both enrichment media and 60 acid-resistant PNSB were isolated. All these were identified as Rhodopseudomonas palustris. R. palustris KKSSR66 was most effective in providing siderophores, NH 4 + , and PO 4 3− ; R. palustris strains KTSWR26, KKSSG39, and KTSWR2 in PGPS production. R. palustris KTSSR54 showed highest inhibition against both rice pathogens. They are potentially beneficial PNSB for rice cultivation in acidic soil.

Effects of biochar and biofertilizer on cadmium-contaminated cotton growth and the antioxidative defense system

“…Biofertilizer is comprised of a large number of living bacteria and nutrient elements, and has a significant positive effect on the ecological environment of soil and the growth and development of crops 41,42 . Recently, biofertilizer has been widely reported as a biosorption agent for heavy metals in soil 42,43 . In this study, the addition of exogenous Cd decreased the dry weight of cotton, at the highest dose of exogenous Cd (4 m•kg −1 ), the total dry weight of cotton was the lowest (60.63 g).…”

“…2, 3), which was consistent with the results of Muszyńska et al 61 and Roychoudhury et al 62 . However, the application of biochar and biofertilizer increased the activities of antioxidant enzymes and increased the oxidative stress response of plants to Cd 24,25,43,48 . In this study, biochar and biofertilizer increased the activities of SOD and CAT and reduced the content of MDA and electrolyte leakage rate, effectively alleviating the negative effects of Cd in cotton (Figs.…”

Encapsulation of Rhodopseudomonas palustrisKTSSR54 using beads from alginate/starch blends

“…8 Recently, selected purple non-sulfur bacteria (PNSB) isolated from peat swamp forests in southern Thailand were studied for their acid-tolerant and plant growthpromoting properties and biocontrol activity against fungal pathogens on rice. 9 In acidic environments, where fungal pathogens are naturally harbored, 10 the most effective strain was Rhodopseudomonas palustris KTSSR54 as biofertilizer and also plant-growth promoting bacterium. 9,11 R. palustris belongs to the PNSB group of bacteria, a group widely recognized for metabolic versatility.…”

Potential of Mn2+-Resistant Purple Nonsulfur Bacteria Isolated from Acid Sulfate Soils to Act as Bioremediators and Plant Growth Promoters via Mechanisms of Resistance

“…Among microbes of potential use in bioremediation, PNSB are interesting organisms. This is due to the fact that they are plant growth promoting bacteria (PGPB) that release plant growth promoting substances (PGPS) such as ALA, IAA and siderophores, and the plant nutrients, NH 4 + by N 2 fixation and PO 4 3− by P-solubilization (Nunkaew et al 2014;Khuong et al 2018;Nookongbut et al 2019). With the evidences that PNSB have been successfully applied to paddy fields on normal soil and also to fields on soil in saline and acidic conditions for enhancement rice growth and grain yield (Kantachote et al 2016;Khuong et al 2018).…”

“…PNSB have been isolated from areas contaminated with heavy metals such as Cd, As, Hg, and Pb (Panwichian et al 2010;Mukkata et al 2015;Nookongbut et al 2016;Sakpirom et al 2017). The PNSB R. palustris and Rubrivivax benzoatilyticus have specifically been proved to resist high concentrations of H + , As 5+ , As 3+ , Al 3+ , and Fe 2+ in acidic soils (Khuong et al 2017;Nguyen et al 2018;Nookongbut et al 2019).…”