L Flashcards
(140 cards)
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Lecture No te: Microbial Detection Techniques in Forensics
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Introduction
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Microbial forensics is an evolving field that employs microbiological
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molecular
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biochemical techniques to detect and analyze microorganisms involved in criminal
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investigations
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bioterrorism
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crucial in identifying sources of contamination
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tracking disease outbreaks
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forensic linkages. This lecture will provide an in-depth understanding of microbial detection
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techniques and their applications in forensic sCience.
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- Importance of Microbial Detection in Forensics
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Microbial detection techniques help forensic Cxperts:
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Identify pathogenic or unique microbial strains ]linked to criminal cases.
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Trace sources of biological threats and bioterrorism agents.
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Differentiate natural outbreaks from deliberate microbial releases.
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Establish microbial signatures associated with specific environments or individuals.
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- Culture-Based Techniques
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Culture-based methods remain fundamental in microbial detection
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involving the growth of
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microorganisms on selective and differential media
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Agar Plate Culturing: Bacteria and rungi are grown on nutrient-rich media to study
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colony morphology and biochemical properties.
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Selective and Differential Media: Speciie gTowth media enhance the isolation of
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target micro bes (e.g.
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MacConkey agar for Gram-negative bacteria).
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Enrichment Cultures: Used for loW-cOncentration microbes
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allowing preferential
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growth before analysis.
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Limitations:
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Time-consuming (24-72 hours for bacterial growth).
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Some microbes are non-culturable under standard laboratory conditions.
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3. Microscopy-Based Techn iques
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Microscopic examination provides direct visualization of microbial cells.
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Light Microscopy: Used for Gram staining and morphological characterization of
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bacteria.
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Fluorescence Microscopy: Uses fluorescent dves to detect specific bacterial species.
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Electron Microscopy: Provides high-resolution images of microbial ultrastructure
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essential for viral detection.
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4. Molecular Detection Techniques
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Molecular techniques provide high specificity and sensitivity for microbial identification.
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Molecular techniques provide high specificity and sensitivity for microbial identification.
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Molecular
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Detection Techniques
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essential for
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viral detection.
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Electron Microscopy: Provides high-resolution images of microbial ultrastructure
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Fluores cence Micros copy: Uses fluorescent dyes to detect specific
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bacterial species.
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bacteria.
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Light Microscopy: Used for Gram staining and morphological characterization of
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Microscopic examination provides direct visualızation of microbial cells.
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3. Microscopy-Based Techniques
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Some
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standard
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nmicrobes are non-culturable
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under laboratory conditions.
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Time-consuming
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(24-72
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hours
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for
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bacterial growth).
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Limitations:
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growth before analysis.
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Selective and Differential Media: S]
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Enrichment
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Cultures: Used
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for
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low-concentration microbes
allowing preferentíal
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for Gram-negative
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target microbes (e.g.
MacConkey
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agar bacteria).
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e growth media enhance the ísolation of
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Polymerase Chain Reaction (PCR): Amplifies microbial DNA
allowing rapid
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Quantitative PCR (qPCR): Measures microbial load in a sample.
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Reverse Transcription PCR (RT-PCR): Detects RNA viruses.
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hole Genome Sequencing (WGS); Derermines the complete genetic profile of a
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microorganism
enabling precise strain identification.
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Metagenomic Sequencing: Identifies complex microbial communities from forensic
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detection.
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as:
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samples.
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Advantages:
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Highly sensitive and specific.
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Allows identification of non-culturable micro bes.
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Rapid turnaround time compared to cultıure-based methodS.
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5. Immunological Detection Techniques
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Immunological assays rely on antigen-antibody interactions for microbial identification.
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Enzyme-Linked Immunosorbent Assav (ELISA): Detects microbial toxins or
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specific antigens.
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Lateral Flow Assays (LFAs): Portable and rapid tests used in field settings (e.g-s
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rapid anthrax detection kits).
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Western Blotting: Confirms microbial protein presence using antibody binding.
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6. Biosensors and Nanotechnology in Microbial Detection
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Recent advancements have integrated nanotechno logy and biosensors into microbial forensic
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investigations.
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Biosensors: Devices that detect microbial DNA
proteins
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electrochemical or optical signals.
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Nanoparticles: Enhance sensitivity in microbial detection assays (e.g.
gold
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nanoparticles for colorimetric detection).
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Lab-on-a-Chip Devices: Miniaturized forensic tools for rapid
on-site microbial
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detection.
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7. Challenges in Microbial Detection for Forensic Applications
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Despite technological advancements
microbial forensic investigations face challenges suo
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Sample Degradation: Microbial DNA and RNA degrade over time
affecting
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detection accuracy.
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shorörpoweCopssTtion: Differentiating forensic microbes from backgr
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microbiota can be complex.
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Polymerase Chain Reaction (PCR): Amplifies microbial DNA
allowing rapid
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Quantitative PCR (qPCR): Measures microbial load in a sample.
108
Reverse Transcription PCR (RT-PCR): Detects RNA viruses.
109
hole Genome Sequencing (WGS); Derermines the complete genetic profile of a
110
microorganism
enabling precise strain identification.
111
Metagenomic Sequencing: Identifies complex microbial communities from forensic
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detection.
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as:
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samples.
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Advantages:
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Highly sensitive and specific.
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Allows identification of non-culturable micro bes.
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Rapid turnaround time compared to cultıure-based methodS.
119
5. Immunological Detection Techniques
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Immunological assays rely on antigen-antibody interactions for microbial identification.
121
Enzyme-Linked Immunosorbent Assav (ELISA): Detects microbial toxins or
122
specific antigens.
123
Lateral Flow Assays (LFAs): Portable and rapid tests used in field settings (e.g-s
124
rapid anthrax detection kits).
125
Western Blotting: Confirms microbial protein presence using antibody binding.
126
6. Biosensors and Nanotechnology in Microbial Detection
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Recent advancements have integrated nanotechno logy and biosensors into microbial forensic
128
investigations.
129
Biosensors: Devices that detect microbial DNA
proteins
130
electrochemical or optical signals.
131
Nanoparticles: Enhance sensitivity in microbial detection assays (e.g.
gold
132
nanoparticles for colorimetric detection).
133
Lab-on-a-Chip Devices: Miniaturized forensic tools for rapid
on-site microbial
134
detection.
135
7. Challenges in Microbial Detection for Forensic Applications
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Despite technological advancements
microbial forensic investigations face challenges suo
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Sample Degradation: Microbial DNA and RNA degrade over time
affecting
138
detection accuracy.
139
shorörpoweCopssTtion: Differentiating forensic microbes from backgr
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microbiota can be complex.
