Alleviation of xenobiotic stress in Helianthus annuus plants via a system of Rhodococcus erythropolis IGTS8 and Brevibacillus formosus HMA5.

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, Brevibacillus formosus 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 Brevibacillus formosus HMA5 and Rhodococcus erythropolis IGTS8 revealed an oil degradation capacity of 90%. The growth performance of the Helianthus annuus (V120 cultivar) in untreated soil indicates its potential for phytoremediation of crude oil-contaminated sites. Microbial augmentation using a consortium of Brevibacillus formosus HMA5 and Rhodococcus erythropolis 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.