Diversity of Microorganisms PDF

Diversity of Microorganisms Microbial diversity is defined as the variability among living organisms. The main key of microbial diversity on earth is due to evolution. The structural and functional diversity of any cell represents its evolutionary event which occurred through...

Diversity of Microorganisms Microbial diversity is defined as the variability among living organisms. The main key of microbial diversity on earth is due to evolution. The structural and functional diversity of any cell represents its evolutionary event which occurred through Darwinian Theory of natural selection. Natural selection and survival of fittest theory is involved on the microorganisms. This includes diversity within species, between species and of ecosystems.  Microbes can be divided into cellular (bacteria, archaea, algae, protozoa, and fungi) and acellular (viruses, viroids, and prions). The cellular microorganisms can be subdivided into those that are prokaryotic (bacteria and archaea) and those that are eukaryotic (algae, protozoa, and fungi). For a variety of reasons, acellular microorganisms are not considered by most scientists to be living organisms. Thus, rather than using the term microorganisms to describe them, viruses, viroids, and prions are more correctly referred to as acellular microbes or infectious particles.  A major biological division separates the eukaryotes and prokaryotes. Cells from animals plants, fungi are eukaryotes.(Greek for ‘true nucleus’) Bacteria and blue green algae belong to the prokaryotes (Geek for “primitive nucleus”) Differences between and prokaryotes and their structures Microbial habitats  THE DOMAIN BACTERIA There are two domains of prokaryotic organisms: Domain Bacteria and Domain Archaea. The bacteriologist’s most important reference is a five-volume set of books entitled Bergey’s Manual of Systematic Bacteriology. The domain Archaea is divided into two phyla and several classes and orders within these phyla. The domain bacteria is divided into 18 phyla and several classes and orders.  Bacteria first arose on earth approximately 4 billion years ago, and they were the first forms of life on Earth. Bacteria and archaea were the most prevalent kinds of organisms on Earth. Characteristics of Bacteria They are omnipresent (soil,water, air) Unicellular (single celled), microscopic, prokaryotic organism. Nucleoid-irregularly shaped does not have a nuclear membrane Thick cell wall outside the membrane, plasma membrane and cytoplasm Movement: flagella and pili Bacteria Shapes  Sexual reproduction is absent but genetic recombination occurs ie Conjugation, Transformation, Transduction. Metabolism: Autotrophs or heterotrophs They lack true chlorophyll but few photosynthetic bacteria posses a type of chlorophyll (Bacteriochlorophyll)  Biochemical and Metabolic Activities As bacteria grow, they produce many waste products and secretions, some of which are enzymes that enable them to invade their host and cause disease. The pathogenic strains of many bacteria, such as Staphylococci and Streptococci, can be tentatively identified by the enzymes they secretes. Pathogenicity (virulence factors) Many pathogens are able to cause disease because they possess capsules, pili, or endotoxins (biochemical components of the cell walls of Gram negative bacteria), or because they secrete exotoxins and exoenzymes that damage cells and tissues. Pathogenic bacteria Pathogenic Bacteria Disease Streptococcus and Pseudomonas Pneumonia Bacillus anthracis Anthrax Bordetella pertussis Whooping cough or pertussis Corynebacterium diphtheriae Diphtheria Clostridium tetani Tetanus Neisseria gonorrhoeae Gonorrhea Nonpathogenic bacteria Example Significance Staphylococcus epidermidis A part of normal skin flora Lactobacillus acidophilus A part of normal intestinal flora Normal flora within the large and small intestines, which breakdown Escherichia coli undigested sugars and produce biotin and vitamin K Normal flora in the colon; use in the Bifidobacteria production of probiotics Normal intestine flora, which breakdown useful nutrients and Bacteroids prevents pathogenic bacteria from colonizing the intestines, Brevibacterium linens Used in the cheese production  Genetic Composition Most modern laboratories are moving toward the identification of bacteria using some type of test procedure that analyzes the organism’s deoxyribonucleic acid (DNA) or ribonucleic acid (RNA). DNA found in the circular form less organized called nucleoid Plasmid: circular DNA Procedures are collectively referred to as mmolecular diagnostic procedures. The composition of the genetic material (DNA) of an organism is unique to each species. Through the use of 16S rRNA sequencing, a researcher can determine the degree of relatedness between two different bacteria.  Ribosomes are 70s type (50S and 30S type) Synthesize proteins Unique Bacteria Rickettsias, Chlamydias, and Mycoplasmas, but they do not possess all the attributes of typical bacterial cells. Thus, they are often referred to as “unique” or “rudimentary” bacteria. Because they are so small and difficult to isolate, they were formerly thought to be viruses. Rickettsias and chlamydias are bacteria with a Gram negative type cell wall. They are obligate intracellular pathogens that cause diseases in humans and other animals. Characteristic features of fungi Fungi are “achlorophyllous” heterotrophic and spore bearing organism surrounded by cell wall made up of chitin. Eukaryotic organism have true nucleus enclosed with membrane includes yeast, molds, mushrooms Cosmopolitan in distribution Habitats: soil, dead and decaying matter, plants, animals, food, water, air Heterotrophs , secretes digestive enzymes No photosynthesis  Growth rate is slow when compared to bacteria Tolerate to high sugar and acidic pH Store food in the form of glycogen or oil Fungi have small nucleus with repetitive DNA Ex: Candida albicans, Mucor , Fusarium, Puccinia  ALGAE Algae are eukaryotic organisms that have no roots, stems, or leaves but do have chlorophyll and other pigments for carrying out photosynthesis. Algae can be multicellular or unicellular. Food accumulates in the form of polysaccharides  Protozoa Microscopic acellular animalcules existing singly or colonies, without tissue and organs having one or more nuclei. Protozoa do not have any cell walls, instead they contain pellicle. The structure of Protozoa is similar to the eukaryotic cells. One-celled animals found worldwide in most habitats. Most species are free living Infections range from asymptomatic to life threatening, depending on the species and strain of the parasite and the resistance of the host. Ex: Trypanosoma, Trichonympha, Plasmodium, Paramecium.  The largest protozoa are found in deep-sea–dwellings known as xenophyophores, which can be 20 cm in diameter. The smallest one is Plasmodium falciparum, which size can be 1-2 micrometers in diameter. Nutrition Nutrition type is holozoic: require organic materials (particulate or in solution) Feed on dead plants or animals, bacteria or algae Parasitic protozoa feed on fluids and tissues of the host (plasma or blood cells) Symbiotic : Entamoeba gingivalis : commensal (symbiotic) Amoeba engulf particulate food or droplets through a sort of temporary mouth, perform digestion and absorption in a food vacuole, and eject the waste substances. Classification  Paramecium Plasmodium Amoeba Trypanosoma Beneficial effects of Protozoa Provide food for insect larvae, worms, fishes etc Insect control: by persisting in their body Persist in the insect gut : Aid in cellulose digestion Help in sanitation : feed on organic matter and purify water Used in medical and biological research Harmful effect of Protozoan Disease in Humans: Plasmodium falciparum (causes malaria), Entamoeba histolytica (causes amoebic dysentery), Trypanosoma brucei (causes sleeping sickness). Water pollution: drinking water Reduction in soil fertility  They can be crystallized Lack their own enzyme system but interact with host enzyme system Viruses as living thing They have genetic material Undergo mutation Get destroyed by UV rays Highly infectious and spread disease very quickly. Habitat Active virus reside within in the host body Within bacterial cell, animal cell, plant cell  Single infectious particle of virus : virion, capsid with enclosed nucleic acid Smallest infectious agents causing diseases: no protein coat contains RNA as infectious particle  Shapes of virus Baltimore classification (1971) classification system nucleic acid (DNA or RNA), strandedness (single-stranded or double-stranded), Sense, and method of replication Structure of bacteriophage Human diseases  Plant viruses: TMV