Title: Isolation and screening of autochthonous beneficial microorganisms from chemically remediated organochlorine pesticide soil in Nghe An Province, Vietnam
Authors: Dinh Hong Duyen,, Bui Thi Thu Huong, Ngo Thao Nguyen
Volume: 10
Issue: 8
Pages: 170-179
Publication Date: 2026/08/28
Abstract:
Chemical oxidation, principally the Fenton process, is the technology applied to most of Vietnam's 1,652 suspected organochlorine pesticide (OCP) hotspots, but chemically treated soil is characteristically acidified, carbon-depleted and biologically impoverished, and a subsequent biological step is required before it can support crops. The microbial products currently applied for that purpose are commercial formulations of non-native origin whose persistence in such a matrix is unverified. This study characterised OCP-contaminated soil after chemical oxidation at three legacy storage sites in Tan Ky District, Nghe An Province, and isolated autochthonous functional microorganisms as candidates for a site-matched bio-inoculant. Nine soil samples were analysed by Vietnamese standard methods, and nitrogen-fixing, phosphate-solubilising and cellulolytic microorganisms were isolated on Ashby, NBRIP and Hans media. Treated soil was strongly acidic (pH 3.58-3.96), very poor in organic matter (0.66-0.78%) and supported only 3.82-5.09 × 10? CFU g?¹ total aerobic microorganisms. Eleven functional isolates were nevertheless recovered without enrichment. Nitrogen fixation ranged from 1.85 ± 0.05 to 3.12 ± 0.05 mg NH?? L?¹, phosphate solubilisation from 93.12 ± 1.82 to 183.97 ± 1.61 mg PO?³? L?¹, and cellulolytic clearing zones from 12 to 16 mm; seven isolates formed colonies on medium amended with 2,4'-DDT at 0.01 and 0.5 ppb. Six strains - A1, A2K, BL1, BP1(2), BX1 and BX2 - combined high activity with growth under DDT. Because the concentrations tested lie far below field residues and the isolates are not yet identified molecularly, the screening indicates absence of acute sensitivity rather than demonstrated field tolerance.