Effects of Endophytic and Rhizosphere Bacteria on Antioxidant Capacity and Fruit Phytochemical Composition of Muna Local Tomato (Solanum lycopersicum L.).

Abstract

<b>Background and Objective:</b> Muna local tomato (<i>Solanum lycopersicum</i> L.) is a valuable local genetic resource with potential as a functional food due to its bioactive compounds and antioxidant activity. However, the use of endophytic-rhizosphere bacterial consortia to improve the phytochemical quality and antioxidant capacity of local tomatoes remains limited. This study aimed to evaluate the effects of single isolates and consortia of endophytic-rhizosphere bacteria on the antioxidant activity and phytochemical profile of Muna local tomato fruits. <b>Materials and Methods:</b> The experiment was arranged in a randomized block design with eight treatments, consisting of a control, <i>Pseudomonas</i> sp. SWRII B02, <i>Bacillus</i> sp. CKD061, <i>Pseudomonas</i> sp. Ke03 and combinations of two and three bacterial isolates. Antioxidant activity was determined using the DPPH assay, while phytochemical profiling was performed using LC-MS/MS. Quantitative data, including DPPH inhibition and IC₅₀ values, were analyzed by ANOVA followed by DMRT at α = 0.05. <b>Results:</b> All isolate combinations were compatible <i>in vitro</i>. Biological agent treatments enhanced antioxidant activity compared with the control. <i>Bacillus</i> sp. CKD061 exhibited the strongest antioxidant activity, with the lowest IC₅₀ value of 41.15 ppm, while the consortium of <i>Pseudomonas</i> sp. SWRII B02 and <i>Bacillus</i> sp. CKD061 was the most effective bacterial combination, with an IC₅₀ value of 47.14 ppm. The LC-MS/MS analysis revealed differences in phytochemical compounds among treatments. Fucosylthreonine, hupeheninoside and triacetoxypiperidinone were detected in all treatments. Solasodine glycoside was detected in the control and <i>Bacillus</i> sp. The CKD061 treatments, whereas tomatidine was detected only in the consortium of <i>Pseudomonas</i> sp. SWRII B02 and <i>Bacillus</i> sp. CKD061. After one week of storage, the metabolite profile changed, as indicated by the presence of N-fructosylvaline, N-succinyl-2-amino-6-oxo-L-pimelic acid, tetrodamine and epivolkenin. <b>Conclusion:</b> <i>Bacillus</i> sp. CKD061 and its consortium with <i>Pseudomonas</i> sp. SWRII B02 have potential as bioinoculants to improve the functional quality of Muna local tomato fruits.