Influence of Water Availability and Bacillus Inoculation on Morphophysiology, Biochemistry and Secondary Metabolite...

Lippia origanoides, commonly known as 'alecrim-pimenta', is an aromatic shrub with pharmacological and agrochemical potential. Bacterial treatments enhance the overall stress response of the plant, affecting morphophysiological and biochemical parameters and stimulating the biosynthesis of secondary metabolites of industrial relevance. This study aimed to determine the influence of bacterial inoculation on the morphophysiology, biochemistry, yield, and composition of L. origanoides essential oil under varying water availability. Plants were inoculated with different Bacillus strains: B. cereus (C240), B. megaterium (RAB2), B. subtilis (IN-937b), and a consortium of these bacterial strains. At 33 days after inoculation, plants were irrigated to 25 or 75% of pot capacity for 37 days, resulting in a total experimental period of 70 days. Biometric evaluations were performed at 16, 40, 54, and 68 days, physiological assessments at 19, 41, 55, and 69 days, and biochemical and essential oil analyses at the end of the experiment. Data were analyzed using two-way analysis of variance with Tukey and Bonferroni tests (p ≤ 0.05). Water availability was the main factor affecting morphophysiological parameters, as well-irrigated plants produced more vegetative and reproductive organs and water-limited plants accumulated osmoprotective compounds. Although the essential oil yield did not differ significantly among treatments, plants inoculated with bacterial strains produced terpenoids with antioxidant and insecticidal properties. The results demonstrate the potential of Bacillus inoculants to enhance secondary metabolism in L. origanoides, supporting sustainable bioproduct development and biotechnological applications.