Evaluating the Effect of an Essential Oil Blend on the Growth and Fitness of Gram-Positive and Gram-Negative Bacteria
The increasing prevalence of antibiotic-resistant bacteria has necessitated the exploration of alternative antimicrobial agents, particularly natural products like essential oils. This study investigated the antibacterial potential of a unique blend of four essential oils (EOB) across a gradient of...
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MDPI AG
2025-04-01
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| Online Access: | https://www.mdpi.com/2079-7737/14/4/437 |
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| author | Kelechi A. Ike Paul C. Omaliko Mizpha C. Fernander Brittany M. Sanders James M. Enikuomehin Joel O. Alabi Oludotun O. Adelusi Ahmed E. Kholif Misty D. Thomas Uchenna Y. Anele |
| author_facet | Kelechi A. Ike Paul C. Omaliko Mizpha C. Fernander Brittany M. Sanders James M. Enikuomehin Joel O. Alabi Oludotun O. Adelusi Ahmed E. Kholif Misty D. Thomas Uchenna Y. Anele |
| author_sort | Kelechi A. Ike |
| collection | DOAJ |
| description | The increasing prevalence of antibiotic-resistant bacteria has necessitated the exploration of alternative antimicrobial agents, particularly natural products like essential oils. This study investigated the antibacterial potential of a unique blend of four essential oils (EOB) across a gradient of concentrations (0.1 to 50%) against Gram-positive and Gram-negative bacteria using an adapted broth microdilution method, minimum inhibitory concentrations (MICs), and 24-h growth assays. The Gram-positive bacteria were <i>Staphylococcus epidermidis</i> and <i>Bacillus subtilis</i>, while the Gram-negative bacteria were <i>Escherichia coli</i> and <i>Klebsiella aerogenes</i>. The results demonstrated that the EOB exerted a concentration-dependent inhibitory effect on bacterial growth, with MICs determined at 25% for all the species tested. Growth curve analysis revealed that lower concentrations of the EOB (0.1 to 0.78%) allowed for normal bacterial proliferation, while at intermediate concentrations (1.56 to 3.13%), inconsistent trends in growth were exhibited. At higher concentrations (25 and 50%), the EOB effectively halted bacterial growth, as indicated by flat growth curves. The increase in the lag phase and the decrease in the growth rate at a sub-MIC concentration (12.5%) suggest a significant effect on bacterial adaptation and survival. Relative fitness analyses further highlighted the inhibitory effects of higher essential oil concentrations. <i>S. epidermidis</i> and <i>E. coli</i> had a significant (<i>p</i> < 0.05) reduction in fitness starting from the 6.25% concentration, while the other two species experienced a significant (<i>p</i> < 0.001) reduction in relative fitness from a concentration of 12.5%. These findings underscore the potential of this EOB as an effective antimicrobial agent, particularly in the context of rising antibiotic resistance. Furthermore, the study suggests that the EOB used in the present study could be integrated into therapeutic strategies as a natural alternative or adjunct to traditional antibiotics, offering a promising avenue for combating resistant bacterial strains. |
| format | Article |
| id | doaj-art-e13c6665a3e24375940938406fe2d68b |
| institution | DOAJ |
| issn | 2079-7737 |
| language | English |
| publishDate | 2025-04-01 |
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| series | Biology |
| spelling | doaj-art-e13c6665a3e24375940938406fe2d68b2025-08-20T03:14:17ZengMDPI AGBiology2079-77372025-04-0114443710.3390/biology14040437Evaluating the Effect of an Essential Oil Blend on the Growth and Fitness of Gram-Positive and Gram-Negative BacteriaKelechi A. Ike0Paul C. Omaliko1Mizpha C. Fernander2Brittany M. Sanders3James M. Enikuomehin4Joel O. Alabi5Oludotun O. Adelusi6Ahmed E. Kholif7Misty D. Thomas8Uchenna Y. Anele9Department of Animal Sciences, North Carolina Agricultural and Technical State University, Greensboro, NC 27411, USADepartment of Animal Sciences, North Carolina Agricultural and Technical State University, Greensboro, NC 27411, USADepartment of Biology, North Carolina Agricultural and Technical State University, Greensboro, NC 27411, USADepartment of Biology, North Carolina Agricultural and Technical State University, Greensboro, NC 27411, USADepartment of Animal Sciences, North Carolina Agricultural and Technical State University, Greensboro, NC 27411, USADepartment of Animal Sciences, North Carolina Agricultural and Technical State University, Greensboro, NC 27411, USADepartment of Animal Sciences, North Carolina Agricultural and Technical State University, Greensboro, NC 27411, USADepartment of Animal Sciences, North Carolina Agricultural and Technical State University, Greensboro, NC 27411, USADepartment of Biology, North Carolina Agricultural and Technical State University, Greensboro, NC 27411, USADepartment of Animal Sciences, North Carolina Agricultural and Technical State University, Greensboro, NC 27411, USAThe increasing prevalence of antibiotic-resistant bacteria has necessitated the exploration of alternative antimicrobial agents, particularly natural products like essential oils. This study investigated the antibacterial potential of a unique blend of four essential oils (EOB) across a gradient of concentrations (0.1 to 50%) against Gram-positive and Gram-negative bacteria using an adapted broth microdilution method, minimum inhibitory concentrations (MICs), and 24-h growth assays. The Gram-positive bacteria were <i>Staphylococcus epidermidis</i> and <i>Bacillus subtilis</i>, while the Gram-negative bacteria were <i>Escherichia coli</i> and <i>Klebsiella aerogenes</i>. The results demonstrated that the EOB exerted a concentration-dependent inhibitory effect on bacterial growth, with MICs determined at 25% for all the species tested. Growth curve analysis revealed that lower concentrations of the EOB (0.1 to 0.78%) allowed for normal bacterial proliferation, while at intermediate concentrations (1.56 to 3.13%), inconsistent trends in growth were exhibited. At higher concentrations (25 and 50%), the EOB effectively halted bacterial growth, as indicated by flat growth curves. The increase in the lag phase and the decrease in the growth rate at a sub-MIC concentration (12.5%) suggest a significant effect on bacterial adaptation and survival. Relative fitness analyses further highlighted the inhibitory effects of higher essential oil concentrations. <i>S. epidermidis</i> and <i>E. coli</i> had a significant (<i>p</i> < 0.05) reduction in fitness starting from the 6.25% concentration, while the other two species experienced a significant (<i>p</i> < 0.001) reduction in relative fitness from a concentration of 12.5%. These findings underscore the potential of this EOB as an effective antimicrobial agent, particularly in the context of rising antibiotic resistance. Furthermore, the study suggests that the EOB used in the present study could be integrated into therapeutic strategies as a natural alternative or adjunct to traditional antibiotics, offering a promising avenue for combating resistant bacterial strains.https://www.mdpi.com/2079-7737/14/4/437antimicrobial activitybacterial growthMICpathogensgrowth kineticsfitness cost |
| spellingShingle | Kelechi A. Ike Paul C. Omaliko Mizpha C. Fernander Brittany M. Sanders James M. Enikuomehin Joel O. Alabi Oludotun O. Adelusi Ahmed E. Kholif Misty D. Thomas Uchenna Y. Anele Evaluating the Effect of an Essential Oil Blend on the Growth and Fitness of Gram-Positive and Gram-Negative Bacteria Biology antimicrobial activity bacterial growth MIC pathogens growth kinetics fitness cost |
| title | Evaluating the Effect of an Essential Oil Blend on the Growth and Fitness of Gram-Positive and Gram-Negative Bacteria |
| title_full | Evaluating the Effect of an Essential Oil Blend on the Growth and Fitness of Gram-Positive and Gram-Negative Bacteria |
| title_fullStr | Evaluating the Effect of an Essential Oil Blend on the Growth and Fitness of Gram-Positive and Gram-Negative Bacteria |
| title_full_unstemmed | Evaluating the Effect of an Essential Oil Blend on the Growth and Fitness of Gram-Positive and Gram-Negative Bacteria |
| title_short | Evaluating the Effect of an Essential Oil Blend on the Growth and Fitness of Gram-Positive and Gram-Negative Bacteria |
| title_sort | evaluating the effect of an essential oil blend on the growth and fitness of gram positive and gram negative bacteria |
| topic | antimicrobial activity bacterial growth MIC pathogens growth kinetics fitness cost |
| url | https://www.mdpi.com/2079-7737/14/4/437 |
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