The Potential of Mesophilic Bacteria for Heavy Metal Bioremediation in Agriculture under Climate Change in The Gambia

Abstract

Crop and livestock production are critical to food security in The Gambia, yet yields have declined, partly due to the impacts of climate change and environmental pollution. This study investigated the potential of mesophilic bacteria (20-40 °C) for heavy metal bioremediation in agriculture under changing climatic conditions. Given the importance of groundnuts and rice, especially rice, consumed at 117 kg/person/year and cultivated across diverse ecosystems, the study explored farmers' perceptions of climate variability and pollution. A mixed-methods approach was used, with a quantitative sample size of 432 and qualitative data gathered through focus groups and eight key informant interviews across six agricultural regions. Results indicated widespread awareness among farmers of climate change, but limited knowledge of heavy metal pollution and bioremediation. Major constraints to production included poor access to water, credit, quality inputs, and rising salinity. Laboratory experiments isolated Pseudomonas fluorescens, Pseudomonas aeruginosa, Bacillus sp., and Grimontia hollisae for heavy metal bioremediation tests. Bacillus sp. exhibited the highest bioremediation efficiency, particularly on Cu and Fe media, reaching optical density (OD) values of 1.0 (Cu at 28 and 98 ppm, day 5) and 0.9 (Fe at 50 ppm, day 1) with sustained growth. P. aeruginosa showed immediate performance, ranking second in both Cu and Zn bioremediation. It achieved a rapid OD peak of 0.6 on day 1 at 58 ppm and demonstrated substantial growth in Zn media. P. fluorescens had the most robust and sustained OD responses across low and high Zn levels, although less than Bacillus sp. in Cu and Fe stress media. These performances indicated promise in Zn, Fe, and Cu remediation, thus highlighting their potential application in climate-resilient, pollution-aware farming practices.