The human body is naturally inhabited by a wide variety of microbes, collectively referred to as normal flora. To investigate the diversity of these microbes at different sites of the body, swabs were taken from the skin behind the ear and back of the throat and cultivated on blood agar and mannitol salt agar plates. Based on colony morphology and Gram staining, Staphylococcus Aureus and Escherichia Coli were tentatively identified as the most prominent normal flora cultured from the skin and throat respectively.
How Do I Choose the Right Writer?
We match you with a writer based on your subject and academic level, but you can also request a preferred writer if you have worked with someone before. Browse writer profiles or let our system pick the best fit for your needs. Each writer brings specialized knowledge in their field, ensuring subject-matter expertise for your assignment. Students looking for an essay writer can review qualifications to find their perfect match. Our team ensures every writer is vetted for expertise, so you are always in good hands.
Aim:
To cultivate normal flora present on human skin and in the throat using differential selective media.
To identify the specific bacteria grown from each region by observing the morphology of the colonies on the agar plates and Gram stained slides.
Introduction:
The human body is inhabited by a wide variety of microbes. In a healthy human internal tissue are normally free of microorganisms whereas surface tissues are in constant contact with environmental organisms and become readily colonized by certain microbial species (Toddar 2005). The mixture of organisms regularly found at any anatomical site is referred to as the normal flora or normal biota. Each body surface has its own characteristic resident biota made up of particular microbial species (Ingraham & Ingraham, 2004). The type of bacteria found in a certain location depends on environmental needs such as ideal temperature, pH, physiology and available nutrients. For example, areas such as the armpit, navel or the back of the throat harbour more microorganisms due to the added moisture, higher body temperature and greater concentration of skin surface lipids (Baron 1996).
To aid in the isolation and identification of individual types of bacteria present in our normal flora specialized growth media can be used. Selective media is used to either encourage or inhibit growth depending on the phenotype of the organism. In addition, differential media can help identify between two closely related bacteria that have small phenotypic differences (Ingraham & Ingraham, 2004). Blood agar and mannitol salt agar are examples of commonly used media that are both selective and differential, aiding in the growth promotion, identification and discrimination of common human normal flora. This study aims to investigate and identify the normal flora diversity found on the human body using these standard microbiology techniques.
What Is Your Refund Policy?
If your paper does not meet your instructions, we offer a money-back guarantee. Contact support within 7 days, and we will review your case promptly to ensure fairness and satisfaction. We believe in transparent policies that protect your investment in academic success. Your trust is our priority, and we strive to make every experience seamless. Our paper writing service stands behind every order with confidence.
Methods:
Resident bacteria were sampled from two anatomical sites, the skin behind the ear and the back of the throat. Blood agar and mannitol salt agar plates were used; incubation time was 24 hours at temperature of 37°C. Gram staining tests and haemolysis were applied to detect colonies and identify them.
Results:
A number of different colonies were observed on both agar plates following isolation of normal flora from the skin and throat. Table 1 outlines the colony description, blood agar haemolysis and subsequent Gram stain from both anatomical sites sampled. On both plates Cocci bacteria were identified; Gram positive were present at both BA plates, and Gram negative bacteria were only identified at the back of the throat. Types of haemolysis were also different: beta type for sample from the skin, and gamma type for throat sample.
Table 2 presents the findings of normal flora colonies grown on mannitol salt agar. The differences between MSA colonies were more significant than between BA colonies: samples from the back of the throat were Gram negative, and samples from the skin behind the ear were Gram negative. Based on these observations and knowledge of the most abundant normal flora at each site, a preliminary identification of the bacteria isolated was made. The bacteria in the throat is most likely Escherichia Coli and Staphylococcus Aureus bacteria is most likely to be identified at the skin.
Table 1: Colony morphology and Gram stain of resident microbes from the skin and throat, isolated on blood agar.
Can You Help with Thesis Writing?
Absolutely! Our Ph.D.-level writers specialize in theses, providing in-depth research and structured arguments tailored to your academic goals, with drafts delivered in stages for your feedback. From proposal to final defense, we support every phase of your thesis journey. Ace tutors with doctoral expertise guide you through complex research requirements. We ensure your thesis meets the highest academic standards.
Site
Colony Morphology
Haemolysis
Cell Morphology
Gram Stain
Throat
Filamentous flat shaped
Gamma
Cocci
Enterococcus aureus
How Do You Ensure Paper Quality?
Every paper goes through a rigorous quality check—grammar, structure, and originality are verified by editors using advanced tools, ensuring it meets your professors standards. We also provide a free originality report with every order. Our multi-layer review process includes subject experts who verify content accuracy and academic rigor. Our commitment to excellence guarantees a polished final product. Students seeking my assignment help receive thoroughly vetted work at every stage.
Escherichia coli
Gram negative and Gram positive
Skin
Circular convex shaped
Beta
Can I Track My Orders Progress?
Yes! Log into your account to check real-time updates, view drafts, and communicate with your writer to stay in the loop throughout the process. Our transparent tracking system keeps you informed at every milestone. You can also request early drafts to ensure everything is on track. The assignment writer assigned to your project provides regular progress updates for peace of mind.
Cocci
Staphylococcus aureus (25% common)
Streptococcus pyogenes (5% rare)
Gram positive
Table 2: Colony morphology and Gram stain of resident microbes from the skin and throat, isolated on mannitol salt agar.
Can You Write in Different Academic Tones?
Our writers adapt to any tone—analytical, persuasive, or descriptive—matching your assignments requirements and your professors expectations perfectly. Whether it is a formal research paper or a creative essay, we have got you covered. We understand that different disciplines require distinct writing styles and academic voices. Just specify your needs in the order form. Our essay helper team masters every academic style from humanities to sciences.
Site
Colony Morphology
Colour
Cell Morphology
Gram Stain
Throat
Punctiform flat shaped
No color
Cocci
What Types of Papers Do You Handle?
From essays to dissertations, case studies to lab reports, we cover all academic papers across disciplines, customized to your specific needs. Our writers are experts in diverse fields, ensuring every paper is tailored perfectly. Whether you need humanities analysis or STEM technical writing, our team has the expertise. No task is too big or small for our team. Research study bay professionals tackle everything from simple assignments to complex scholarly work.
Neisseria sp.
Neisseria meningitides
Escherichia coli
Proteus sp.
How Do You Protect My Payment Info?
We use secure, encrypted payment gateways to safeguard your financial details, ensuring safe transactions with no risk of data breaches. Your privacy is our top concern, and we follow industry-standard security protocols. Our compliance with PCI DSS standards means your payment information is never stored or compromised. Rest easy knowing your information is protected. Every paper writing transaction processes through bank-level encryption for maximum safety.
Pseudomonas
Aeruginosa
Haemophilus
Influenza
Can You Provide a Bibliography?
Yes, every paper includes a properly formatted bibliography, tailored to your citation style, with credible sources to support your work. Our writers ensure every reference is accurate and up-to-date. We work with APA, MLA, Chicago, Harvard, and other major citation formats for academic precision. You can also request specific sources to be included. Research essay service includes comprehensive bibliographies with peer-reviewed academic sources.
Spirochetes
Gram negative
Skin
Punctiform flat shaped
What Is Your Experience with Academic Levels?
Our writers handle high school to Ph.D.-level papers, with expertise in crafting content that aligns with the complexity and expectations of each level. From simple essays to complex dissertations, we deliver quality every time. Each academic level requires different depths of analysis, and our writers adjust accordingly. Your academic success is our mission. Students at every educational stage can ace my homework with our specialized level-appropriate support.
Small pink or red colony
Cocci
Staphylococcus
Epidermidis
Can You Help with Presentations?
Sure thing! We create compelling slides and scripts for presentations, designed to engage your audience and meet academic standards. Our team ensures your presentation is visually appealing and content-rich. We balance visual design with substantive content to maximize your presentation impact. Just share your requirements, and we will handle the rest. Assessment help extends beyond written work to professional presentation materials.
Staphylococcus aureus
Streptococcus pyogenes
Corynebacteria (Bacilli)
Gram positive
Discussion:
To investigate the diversity of normal flora, areas from the skin and throat were sampled and the resident bacteria isolated on blood agar and mannitol salt agar plates, prior to Gram staining.
How Do You Handle Sensitive Topics?
We approach sensitive topics with care, ensuring confidentiality and respectful handling, with writers trained to maintain academic integrity. Your privacy is guaranteed, and we tailor content to be thoughtful and professional. Our experience with controversial subjects ensures balanced, scholarly perspectives that meet ethical standards. Share any specific guidelines to ensure a perfect fit. Essay writer experts handle delicate subjects with academic rigor and sensitivity.
BA plates are differential: MSA plates are selective and differential. Cultures grew on each half of the plates. The results obtained at BA and MSA plates are different; this may result from several factors: sampling variations, growth variations and approximateness of estimates produced by Gram staining. For throat swabs, results were negative and positive at BA plate, and only negative at MSA plate; for skin swabs, Gram results were positive at both plates. At both halves of the plates major colonies could be identified.
Generally, it was expected to testify greater variety of bacteria at the throat swab compared to skin swab basing on the difference of environments (humidity, higher temperature, exposure to different microorganisms). During the experiment, a slightly greater diversity was indeed observed. Escherichia Coli was determined as major colony at throat sample because BA plate demonstrated gamma haemolysis and the throat swab shown Gram-negative results both times (and Gram-positive results only at BA plate). Different shapes of colonies also correspond to this identification as E. Coli does not have a particular cell arrangement. Staphylococcus aureus were determined as type of colony for skin swab since of its colony type, beta haemolysis reaction and Gram-positive stain, 25% common. Also, Staphylococcus aureus is common for the normal flora of humans found on nasal passages, skin and mucous membranes (Bauman 2008), In order to make more detailed analysis, it is possible to perform catalase test.
To make a conclusion, the results of the experiment demonstrate the diversity and preliminary identification of common normal flora found resident on the skin and throat.