Extracts of five different plant seeds- Syzygium cumini, Pheonix sylvestris, Manilkara zapota, Tamarindus indica, and Annona squamosa- prepared by Microwave Assisted Extraction (MAE) method were screened for their antimicrobial activity against certain phytopathogenic microorganisms. Ethanolic extract of S. cumini was found to possess highest average total activity against susceptible microbes. Total activity was found to have a positive correlation with the extraction efficiency. Methanolic extract of T. indica exerted bactericidal action against Agrobacterium tumefaciens and Pseudomonas syringae. Ethanolic extract of P. sylvestris was able to protect cabbage leaf against Xanthomonas campestris. Acetone extract of M. zapota was able to reduce aflatoxin production in Aspergillus parasiticus by >50 %. Curcumin proved bactericidal against X. campestris.
Table of Contents
1. Preamble
2. Literature Survey
2.1. Synthetic pesticides and its challenges
2.1.1. Effect of pesticides
2.1.2. Risk associated to pesticides
2.1.3. Advantage of plant products over chemical pesticides
2.2. Major Phytochemicals
2.2.1. Phenols and Polyphenols
2.2.2. Terpenoids
2.2.3. Essential oils
2.2.4. Alkaloids
2.2.5. Saponins
2.2.6. Peptides and proteins
2.3. Plant Material
2.3.1. Tamarindus indica
2.3.2. Syzygium cumini
2.3.3. Phoenix sylvestris
2.3.4. Manilkara zapota
2.3.5. Annona squamosa
2.4. Test Microorganisms
2.4.1. Pseudomonas syringae
2.4.2. Pseudomonas marginalis
2.4.3. Pseudomonas caratovorum
2.4.4. Agrobacterium tumefaceins
2.4.5. Xanthomonas campestris
2.4.6. Aspergillus parasiticus
2.5. Extraction of Plant material
2.5.1. Microwave assisted extraction (MAE)
2.6. Antimicrobial susceptibility testing
2.6.1. Antibacterial susceptibility testing
2.6.1.1 Broth dilution assay
2.6.1.2. Minimum inhibitory concentration (MIC)
2.6.1.3. Minimum bactericidal concentration (MBC)
2.6.1.4. Synergistic activity of extract
2.6.2. Antifungal susceptibility testing
2.7. Time required to kill
2.8. Characterization of crude extract
2.8.1. Thin layer chromatography (TLC)
2.8.1.1. Analytical TLC
2.8.1.2. Preparative TLC
3. Experiments
3.1. Plant materials
3.2. Test microorganisms
3.3. Microwave Assisted Extraction (MAE)
3.4. Minimum inhibitory concentration (MIC)
3.4.1. Inoculum preparation
3.4.2. Macrobroth dilution method
3.4.3. Microbroth dilution method
3.4.3.1. Microbroth dilution method against bacteria
3.4.3.2. Microbroth dilution method against fungi
3.5. Minimum bactericidal concentration (MBC)
3.6. Time required to kill
3.7. Disc diffusion assay of antimicrobial agents
3.8. Synergistic effect of extracts
3.9. Separation of crude extract by thin-layer chromatography
3.9.1. Analytical TLC
3.9.2. Preparative TLC
3.9.3. Recovery preparative TLC
3.10. Activity of the isolated compounds
3.11. Experiments with host plants
3.12. Effect of extracts on mycelial growth and aflatoxin production by A. parasiticus
3.13. Test for alkaloids
4. Results and Discussion
4.1. Extraction
4.2. Antibacterial assay
4.2.1. Results of Microbroth dilution assay of extracts
4.2.2. Results of MBC
4.2.3. Results of time required to kill
4.2.4. Results of Microbroth dilution assay of pure plant components
4.2.5. Results of Microbroth dilution assay and disc diffusion assay of antibiotics
4.3. Antifungal assay
4.3.1. Results of Micro broth dilution assay
4.3.2. Results of Microbroth dilution assay of pure plant components
4.3.3. Results of disc diffusion assay of antifungal
4.3.4. Result of effect of extracts on aflatoxin production by A. parasiticus
4.4. Synergistic effect of extracts
4.5. Characterization of crude extract
4.5.1. Results of thin-layer chromatography
4.6. Antibacterial activity of isolated fraction by disc diffusion assay
4.7. Experiments with host plants
5. Final Comments
Research Objectives and Themes
This work aims to evaluate the antimicrobial potential of various plant extracts and their constituents against key plant pathogens, focusing on the management of crop diseases and mycotoxin production. The study screens plant materials for bioactivity, determines inhibitory concentrations, and investigates the synergistic effects of extracts and the mechanisms behind them.
- Antimicrobial screening of various plant seed extracts against phytopathogenic microbes.
- Determination of MIC, MBC, and MFC for potential plant-derived antimicrobial agents.
- Evaluation of the impact of plant extracts on aflatoxin production by Aspergillus parasiticus.
- Characterization of active compounds via thin-layer chromatography (TLC) and assessment of their synergistic potential.
- Validation of anti-phytopathogenic activity in host plant experiments.
Auszug aus dem Buch
2.1. Synthetic pesticides and its challenges
The usage of synthetic pesticides has increased for the control of plant disease due to its effectiveness in controlling phytopathogens. The unrestrained use of these chemicals, under the adage, “if little is effective, a lot more will be powerful” has played ravage with human and other life forms, environment, etc. Due to non-biodegradable nature of chemical pesticides they get accumulated at each trophic level of food chain. Since humans occupy the top level in any food chain, so the maximum amount of harmful chemical pesticides gets accumulated in our bodies. Thus accumulation of such chemicals in living bodies at each trophic level of food chain is called biomagnifications.
2.1.1 Effect of pesticides
The credits of pesticides include enhanced economic potential in terms of increased production of food & fibre, amelioration of vector-borne diseases and then their debits have resulted in serious health implications to man & his environment [Aktar et al., 2009]. The World Health Organization (WHO) estimated that 200,000 people are killed worldwide, every year due to pesticide poisoning [Dubey et al., 2011]. During pesticide spraying, it can enter to body through skin contact and inhalation of aerosols. Among side effects of pesticide are hormonal disruption, cancer, neurotoxicity, birth defects, etc.
Summary of Chapters
1. Preamble: Introduction to the global burden of plant diseases and the necessity for alternative, natural disease management strategies.
2. Literature Survey: Comprehensive review of chemical pesticides, their challenges, major phytochemical classes, and relevant methodology for antimicrobial testing.
3. Experiments: Detailed description of the methodologies used, including plant material collection, extraction, antimicrobial assays, and chromatographic techniques.
4. Results and Discussion: Presentation and analysis of experimental data regarding extraction efficiencies, antimicrobial activity, and the efficacy of plant extracts in reducing plant pathogen growth and mycotoxin production.
5. Final Comments: Concluding overview of the findings, highlighting the potency of specific seeds and the future prospects for natural products in agricultural disease management.
Keywords
Phytopathogens, Antimicrobial plant products, Aflatoxin, Microwave assisted extraction, MIC, MBC, Xanthomonas campestris, Aspergillus parasiticus, Synergistic effect, Thin-layer chromatography, Biopesticides, Crop protection, Phytochemicals, Antibacterial activity, Antifungal activity.
Frequently Asked Questions
What is the core focus of this research?
The research fundamentally explores the potential of natural plant products as sustainable and less toxic alternatives to synthetic pesticides for controlling various phytopathogens.
Which organisms are the primary targets of the study?
The study focuses on several destructive phytopathogenic bacteria, including Pseudomonas syringae, Agrobacterium tumefaceins, Xanthomonas campestris, Pectobacterium caratovorum, and the mycotoxin-producing mold Aspergillus parasiticus.
What is the primary objective of this work?
The primary objective is to screen selected plant extracts and pure phytochemicals for their antimicrobial activities, determine their minimum inhibitory and bactericidal concentrations, and analyze their ability to inhibit aflatoxin production.
Which scientific methods were utilized?
The methodology includes Microwave Assisted Extraction (MAE), broth dilution assays (macro and micro) for MIC and MBC determination, time-kill studies, thin-layer chromatography (TLC) for purification, and disc diffusion assays.
What is covered in the results section?
The results section details extraction efficiencies, provides extensive tabular data on the inhibition percentages of various seed extracts, discusses synergistic effects, and characterizes the antibacterial activity of isolated fractions.
What define the characteristics of this study?
Key terms include antimicrobial activity, crop protection, phytopathogens, plant extracts, biopesticides, and mycotoxin detoxification.
How does the research assess the toxicity of these plant extracts?
The research emphasizes that plant-derived biochemical pesticides are generally less toxic to humans and non-target species compared to synthetic chemical alternatives, making them more sustainable tools for agriculture.
What specific role does Microwave Assisted Extraction (MAE) play?
MAE is identified as an efficient and rapid extraction method that improves the yield of phytoconstituents while minimizing the heat-denaturation of active components, proving superior for specific seed extractions.
Is there a correlation between growth inhibition and aflatoxin production?
The study found varied results, noting that while some extracts reduced both mycelial growth and aflatoxin production, others showed no direct correlation, with certain extracts actually leading to an increase in aflatoxin production despite inhibiting growth.
- Quote paper
- Vijay Kothari (Author), Binjal Darji (Author), Megha Doshi (Author), Jaydeep Ratani (Author), 2012, Antimicrobial Plant Products for Management of Phytopathogens, Munich, GRIN Verlag, https://www.grin.com/document/204568
