Microbial

EcologyBy: Frances Obias-Turiano

Ecology• it is

the scientific study of interactions

among organisms and their

environment, such as the

interactions organisms have with each other and

with their abiotic environme

nt.

Microbial Ecology• Is the study of numerous interrelationships between

microorganisms and the world around them;

how microbes interact with other microbes

how microbes interact with organisms other than microbes

and how microbes interact with the non- living world

around them

Symbiotic Relationship

Involving Microorganism

s

Symbiosis

(Symbiotic Relationship) • Is defined as the living together

in more or less intimate association or close union of two dissimilar organisms

• The organisms that live together in such relationship are called Symbionts.

Neutralism • Is used to describe a symbiotic

relationship in which neither symbionts is affected by the relationship.

• Reflects a situation in which different microorganisms occupy the same ecological niche but have absolutely no effect on each other.

Commensalism

• an association between two organisms in which one benefits and the other derives neither benefit nor harm.

• Ex. Human and indigenous Microflora

Mutualism • symbiotic relationship between individuals of

different species in which both individuals benefit from the association.

• In this type of symbiosis, both organisms of different species rely on one another for nutrients, protection and other life functions, hence, they are usually found living in close proximity.

• Example:Eschericha coli,

which obtains nutrients from food materials ingested by the host and produces vitamins (such as Vitamin K) which are used by the host.

Parasitism • parasitism, relationship

between two species of plants or animals in which one benefits at the expense of the other, sometimes without killing it.

Synergism(Synergetic Infection)

• the interaction or cooperation of two or more organizations, substances, or other agents to produce a combined effect greater than the sum of their separate effects.

Indigenous Microflora of Humans

Indigenous Microflora or Indigenous Microbiota

• “normal Flora” • Includes all the microbes (bacteria, fungi,

protozoa and viruses) that reside on or within that person.

• It has been estimated that our bodies are composed of about 10 trillion cells (including nerve cells, muscle cells, epithelial cells, etc.), and that we have about 10 times that many microbes that live on and within our bodies (10x10 trillion = 100 trillion)

• It has also been estimated that our indigenous microflora is composed of between 500 and 1000 different species.

Eyes andEars

Skin Mouth and upper

Respiratory tract

Gastrointestinal tract

Genitourinary tract (vagina, urethra)

Microflora of the skin

• The resident microflora of the skin consists primarily of bacteria and fungi – approximately 30 different types.

• The most common bacteria on the skin are species of:

- Staphylococcus, - Micrococcus, -Corynebacterium,- Propionibacterium,-P.acnes- causes acne.-Brevibacterium, -and Acinetobacter.

• Staphylococcus aureus• Acinetobacter spp• Bacillus spp• Candida albicans• Corynebacterium spp• Corynebacterium

parvum• Demodex folliculorum• Enterobacter cloacae• Epidermophyton

floccosum• Micrococcus spp• Micrococcus luteus• Mycobacterium spp

• Neisseria spp• Peptostreptococcus spp• Malassezia ovale• Propionibacterium spp• Propionibacterium acnes• Pseudomonas aeruginosa• Sarcina spp• Staphylococcus aureus• Staphylococcus

epidermidis• Staphylococcus

haemolyticus• Streptococcus viridans• Trichophyton spp

Factors Amount of moisture presentpH levelTemperatureSalinity

Presence of chemical wastes such as urea and

fatty acidsPresence of other microbes, which may be

producing toxic substances

Microflora of the eyes and ears

Microflora in the

Gastrointetinal Tract

Binomial name LocationAchromobacter spp Large intestine, small intestine (Ileon)Acidaminococcus fermentans Large intestineAcinetobacter calcoaceticus Large intestineActinomyces spp AmygdalaActinomyces viscosus MouthActinomyces naeslundii MouthAeromonas spp Large intestine, small intestine (Ileon)Aggregatibacter actinomycetemcomitans MouthAnaerobiospirillum spp FecesAlcaligenes faecalis Large intestine, small intestine (Ileon)Arachnia propionica MouthBacillus spp Large intestineBacteroides spp Mouth, amygdalaBacteroides gingivalis MouthBacteroides fragilis General distributionBacteroides intermedius MouthBacteroides melaninogenicus Mouth, feces

Bacteroides pneumosintes Pharynx

Microflora in the Respiratory Tract

Binomial name LocationAcinetobacter spp NasopharynxBurkholderia cepacia complex LungCampylobacter sputorum NasopharynxCandida albicans PharynxCardiobacterium spp NoseChlamydophila pneumoniae LungCitrobacter freundii ThroatEikenella corrodens General distributionHaemophilus spp NasopharynxHaemophilus parainfluenzae PharynxHaemophilus paraphrophilus PharynxKingella spp Upper respiratory TractKingella kingae Upper respiratory TractMoraxella spp NasopharynxMoraxella catarrhalis NasopharynxMycoplasma orale OropharynxMycoplasma pneumoniae Respiratory epitheliumNeisseria spp NasopharynxNeisseria cinerea NasopharynxNeisseria elongata Pharynx

Microflora in the Genitourinary Tract

Binomial name LocationAcinetobacter spp Anterior urethra, vaginaBacteroides spp External genitaliaBifidobacterium spp Vagina

Candida albicans Anterior urethra, external genitalia, vagina

Chlamydia trachomatis Urethra, vagina, fallopian tubes, prostate gland

Clostridiums pp Vagina

Corynebacterium spp Anterior urethra, external genitalia, vagina

Enterobacteriaceae Anterior urethra, external genitalia, vagina

Neisseria gonorrhoeae Urethra, vagina, prostate gland

Streptococcus viridans Anterior urethra, external genitalia, vagina

Eikenella corrodens General distributionStreptococcus anginosus General distributionStaphylococcus aureus PerineumGardnerella vaginalis Female reproductive systemMycoplasma hominis Cervix, vaginaMobiluncus curtisii VaginaMobiluncus mulieris Vagina

• Genitourinary infections fall into two main categories: (1) primary infections due to sexually transmitted pathogenic microorganisms and (2) infections due to members of the resident flora. Genital infections are uncommon in children and increase dramatically in sexually active adults, in whom sexually transmitted diseases are the second most prevalent group of reportable communicable illness in North America. Sexually transmitted pathogens include parasites (Trichomonas vaginalis), bacteria (Treponema pallidum, Neisseria gonorrhoeae, Chlamydia trachomatis, Haemophilus ducreyi), and viruses (Herpes simplex virus, human papillomavirus, human immunodeficiency virus). Genital infections due to the fungus Candida albicans or to members of the endogenous bacterial flora (Bacteroides fragilis and members of the family Enterobacteriaceae) are not known to be sexually transmitted. Bacterial vaginosis occurs when the balance of vaginal flora is upset.

• The urinary tract and urine are normally sterile. Numerous mechanical and biologic processes ensure that microorganisms do not enter the urinary tract. Women are more susceptible to urinary infections because the female urethra is short and because the area around the urethral opening is colonized with potential pathogens (e.g. E coli and E faecalis).

BENEFICIAL EFFECTS OF INDIGENOUS FLORA

Microbial antagonism• “microbes versus microbes” • Our indigenous microflora serve a beneficial

role by preventing other microbes from becoming established in or colonizing a particular anatomic location

• Microbial antagonism is a property that enables a microorganism to kill, injure or slow down the growth of a different microorganism. Bacterial flora benefits the microbial antagonism host. It does this by preventing overgrowth of harmful organisms.

Opportunistic Pathogen

• an organism that exists harmlessly as part of the normal human body environment and does not become a health threat until the body's immune system fails.

• Organisms that are hanging around, waiting for the opportunity to cause infections

Agricultural Microbiology

• Agricultural microbiology is a branch of microbiology dealing with plant-associated microbes and plant and animal diseases. It also deals with the microbiology of soil fertility, such as microbial degradation of organic matter and soil nutrient transformations.

Microbes and the Cycles of Elements of Life

The Nitrogen Cycle

CO2 Cycle

Soil Microorganisms

Bacteria• more dominant group of microorganisms in

the soil and equal to one half of the microbial biomass in soil. Population 100,000 to several hundred millions for gram of soil - Autochthnous - Zymogenous groups. Majority are Heterotrophs. (Common soil bacteria - Arthrobacter, Bacillus, Clostridium, Micrococcus).

Actinomycetes• - intermediate group between bacteria

and fungi. Numerous and widely distributed in soil. Abundance is next to bacteria. 104 - 108/g soil. 70% of soil actinomycetes are Streptomyces. Many of them are known to produce antibiotics. Population increases with depth of soil.

Fungi• More numerous in surface layers of well-

aerated and cultivated soils-dominant in acid soils. Common genera in soil are Aspergillus, Mucor, Penicillium Trichoderma, Alternaria, Rhizopus. Algae – found in most of the soils in number ranges from 100 to 10,000 per g

• Protozoa: Unicellular – population ranges from 10,000 to 100,000 per g of soil. Most of the soil forms are flagellates, amoebae or ciliates. Derive their nutrition by devouring soil bacteria. Abundant in upper larger of the soil. They are regulating the biological equilibrium in soil.

Importance of soil microorganisms

• Involved in nutrient transformation process• Decomposition of resistant components of plant and animal

tissue• Role in microbial antagonism• Participate in humus formation• Predator to nematodes• Surface blooming reduces erosion losses• Improves soil structure• Maintenance of biological equilibrium