Soil bacterial diversity under drought stress and artificial humic acid treatment Raw sequence reads

Using artificial humic substances harbors enormous potential in agriculture to diminish drought stress and increase plant fitness as well as to mitigate climate change by carbon sequestration. Unfortunately, not much is known about the effect of artificially produced humic acid on the soil microbiome and its effect on drought exposed soil. We conducted an experiment investigating the effect of drought stress and artificial humic acid on the bacterial soil microbiome using cultivation-dependent (TSA agar plates) and cultivation-independent (16S amplicon sequencing) methods. Sandy soil was collected from Potsdam, Germany, and exposed to drought stress and artificial humic acid. Drought stress and artificial humic acid influenced bacterial community composition significantly, but only artificial humic acid affected bacterial diversity. The effect artificial humic acid under drought stressed soil changed bacterial community composition and stabilized bacterial diversity. Enriched bacterial families like Pseudomonadaceae, Peptostreptococcaceae, Moraxellaceae and Flavobacterium in drought stressed and artificial humic acid treated soil suggest an adaptation and selection of the soil bacterial microbiome. Further, cultivation dependent methods identified mainly Bacillus, but various taxa like Arthrobacter, Janthinobacterium and Kocurio, which are correlated to natural humic substances. We propose that artificial humic acid application in sandy soil improves the soil bacterial community, mitigates drought stress, favors plant growth promoting taxa and brings enormous potential to sequestrate carbon in soil.