Bioactivity of Selected Phenolic Acids and Hexane Extracts from Bougainvilla spectabilis and Citharexylum spinosum on the Growth of Pectobacterium carotovorum and Dickeya solani Bacteria: An Opportunity to Save the Environment

Abstract

Phenolic acids and natural extracts, as ecofriendly environmental agents, can be used as bio bactericides against the growth of plant pathogenic bacteria. In this study, isolation trails from infected potato tubers and stems that showed soft rot symptoms in fields revealed two soft rot bacterial isolates and were initially identified through morphological, physiological, and pathogenicity tests. The molecular characterization of these isolates via PCR, based on the 16S rRNA region, was carried out by an analysis of the DNA sequence via BLAST and Genbank, and showed that the soft rot bacterial isolates belong to Pectobacterium carotovorum subsp. carotovorum (PCC1) and Dickeya solani (Ds1). The in vitro results of the tested phenolic acids against the cultured bacterial isolates proved that concentrations of 800, 1600, and 3200 μg/mL were the most effective. Ferulic acid was the potent suppressive phenolic acid tested against the Ds1 isolate, with an inhibition zone ranging from 6.00 to 25.75 mm at different concentrations (25–3200 μg/mL), but had no effect until reaching a concentration of 100 μg/mL in the PCC1 isolate, followed by tannic acid, which ranged from 7.00 to 25.50 mm. On the other hand, tannic acid resulted in a significant decrease in the growth rate of the PCC1 isolate with a mean of 9.11 mm. Chlorogenic acid was not as effective as the rest of the phenolic acids compared with the control. The n-hexane oily extract (HeOE) from Bougainvillea spectabilis bark showed the highest activity against PCC1 and Ds1, with inhibition zone values of 12 and 12.33 mm, respectively, at a concentration of 4000 μg/mL; while the HeOE from Citharexylum spinosum wood showed less activity. In the GC/MS analysis, nonanal, an oily liquid compound, was found ata percentage of 38.28%, followed by cis-2-nonenal (9.75%), which are the main compounds in B. spectabilis bark HeOE, and 2-undecenal (22.39%), trans-2-decenal (18.74%), and oleic acid (10.85%) were found, which are the main compounds in C. spinosum wood HeOE. In conclusion, the phenolic acids and plant HeOEs seem to raise the resistance of potato plants, improving their defense mechanisms against soft rot bacterial pathogens.

New Approach for Using of Mentha longifolia L. and Citrus reticulata L. Essential Oils as Wood-Biofungicides: GC-MS, SEM, and MNDO Quantum Chemical Studies

“…All the compounds were identified using their retention times and mass spectra by matching them with those from WILEY 09 and NIST 11 mass spectral databases. Standard Index and Reverse Standard Index measurements, with the Xcalibur 3.0 data system (3.0, Thermo Fisher Scientific Inc., Austin, TX, USA, 2014) of GC/MS, were used to confirm the identification of the compounds, where a value ≥650 is acceptable to confirm the compounds [ 6 , 7 , 15 , 16 , 17 , 18 , 19 , 20 , 45 ].…”

Phenolic Content and Antibacterial Activity of Cupressus sempervirens Leaves Extracts Against Phytopathogenic Bacteria Pectobacterium atrosepticum Causative Agent of Soft Rot on Potato and Clinical Bacteria Strains

“…32 The antibacterial activity of polyphenols has been widely studied. According, to Ashmawy et al, 35 ferulic and tannic acids had a substantial inhibitory impact on the growth of Pectobacterium carotovorum isolates. A mixture of caffeic and chlorogenic acids could prevent bacterial soft rot infection from occurring, and the major phenolic acids detected in the tuber peels that had soft rot antimicrobial effects were chlorogenic, caffeic, and ferulic acids.…”

Foliar Application of Bio-Stimulants Enhancing the Production and the Toxicity of Origanum majorana Essential Oils Against Four Rice Seed-Borne Fungi

“…GC/MS with Xcalibur 3.0 data system has threshold values to confirm that all the MS of the compounds were attached to the library. Therefore, measuring their standard index (SI) and reverse standard index (RSI), values ≥ 650 are acceptable to confirm the compounds [35,[75][76][77][78].…”