Work

Selection of acid sulfate purple nonsulfur bacteria for mitigating methane emissions from paddy soils in the Mekong Delta, Vietnam

Year: 2026

Type: article

Abstract: In lowland rice cultivation, climate change is increasingly intensified by rising greenhouse gas emissions, especially methane (CH 4 ). This study aimed to: (i) isolate and select acid sulfate-tolerant purple nonsulfur bacteria (PNSB) capable of nutrient provision; and (ii) screen and identify PNSB strains that reduce CH 4 emissions. A total of 60 soil and 60 water samples were collected from four acid sulfate rice-growing areas in the Mekong Delta, Vietnam. From these, 118 PNSB strains were isolated, and 100 were selected based on their acid-sulfate tolerance, nitrogen fixation, phosphate solubilization, and indole-3-acetic acid (IAA) production. Among them, strains WHA-1A, WHA-9B, and SPL-4A exhibited the greatest CH 4 emission reduction under both microaerobic light (17.1–61.3%) and aerobic dark (48.2–75.2%) conditions. These strains also demonstrated nitrogen fixation (21.5–22.9 and 19.4–31.4 mg L − 1 ), solubilization of three insoluble phosphate forms—Fe-P, Al-P, and Ca-P for both conditions (21.9–29.6 and 11.9–14.8 mg L − 1 ; 8.12–15.1 and 19.0–30.2 mg L − 1 ; 12.5–27.0 and 18.5–31.4 mg L − 1 , respectively), and IAA production (0.34–1.91 and 2.24–6.28 mg L − 1 ). Based on 16S rRNA gene sequencing, two strains WHA-1A and SPL-4A were identified as Rhodobacter sphaeroides , and WHA-9B was identified as Blastochloris sulfoviridis . These strains show promise for mitigating CH 4 emissions and improving rice growth in acid sulfate soils.

Source: International Microbiology

DOI: 10.1007/s10123-026-00883-4