Alleviation of xenobiotic stress in <i>Helianthus annuus</i> plants via a system of <i>Rhodococcus erythropolis</i> IGTS8 and <i>Brevibacillus formosus</i> HMA5

Abstract

Xenobiotic stress, such as crude oil contamination in soil, is a major environmental challenge that adversely affects plant growth and development. Among five isolates screened for their ability to degrade crude oil, <i>Brevibacillus formosus</i> strain HMA5 was the most potent strain showing oil degradation capacity of 83%. Temperature and incubation period are critical factors that affect hydrocarbon degradation as the best degradation capacity was obtained at temperature range of 30 °C - 40 °C and after 7 days of incubation period as degradation capacity was recorded up to 83%. Moreover, a co-culture of <i>Brevibacillus formosus</i> HMA5 and <i>Rhodococcus erythropolis</i> IGTS8 revealed an oil degradation capacity of 90%. The growth performance of the <i>Helianthus annuus</i> (V120 cultivar) in untreated soil indicates its potential for phytoremediation of crude oil-contaminated sites. Microbial augmentation using a consortium of <i>Brevibacillus formosus</i> HMA5 and <i>Rhodococcus erythropolis</i> IGTS8 mitigates xenobiotic stress and hence may enhance the phytoremediation capacity of sunflower. Bioaugmentation promotes sunflower growth, increases chlorophyll content, and enhances photosynthetic efficiency. Plants grown in bioaugmented soil showed a significant reduction in both stress markers and antioxidant enzyme activities (SOD, CAT, APX, and PPO). This finding presents a sustainable strategy for future applications in the bioremediation of crude oil-contaminated soil.