ENVIRONMENTAL MICROBIOLOGY Environmental microbiology is the study of

ENVIRONMENTAL MICROBIOLOGY Environmental microbiology is the study of the composition and physiology of microbial communities in the environment. The environment in this case means the soil, water, air and sediments covering the planet and can also include the animals and plants that inhabit these areas. Environmental microbiology also involves: Microbial interaction and interaction with macroorganisims. Population biology of microorganisms. Microbial communities genetic and evolutionary processes. Element cycles and biogeochemical processes. Microbial life in extreme and unusual environment

Microbial habitats: Microbes are found in just about every kind of habitat. Microbes are incredibly diverse thriving in environments from the very cold to the extremely hot. They are also tolerant of many other conditions such as limited water availability high salt content and low oxygen levels. Not every microbe can survive in all habitats. Types of microbial habitats: Terrestial(soil ) microbial habitats. Aquatic(water) microbial habitats. Microbial Habitats in Other Organisms. air microbial habitat.

Soil Microbial Habitats Only one percent of microbes that live in soil have been identified. These organisms take part in the formation of soil and are essential components of their ecosystems. Bacteria and fungi that live in soil feed mostly on organic matter such as other plants and animals. These microbes are very sensitive to their local environment. Factors such as the levels of carbon dioxide and oxygen the p. H moisture and temperature all affect the growth of microbes in the soil.

Water Microbial Habitat Microbes live in both fresh and salt water. These organisms include microscopic plants and animals as well as bacteria fungi and viruses. As with other microbes the ones that live in water are adapted to the specific conditions of their environment. Habitats range from ocean water with an extremely high salt content to freshwater lakes or rivers Microbial Habitats in Other Organisms. Microbes also live on other organisms. As with the ones found on people these microbes can be harmful or beneficial to the host. Example: Bacteria grow in nodules on the roots of pea and bean plants. These microbes convert nitrogen from the air into a form that the plants can use. In many ways animals and plants have evolved as habitats for the millions of microbes that call them home.

WATER AS MICROBIAL HABITAT Water is essential to life, but many people do not have access to clean and safe drinking water and many die of waterborne bacterial infections.

MICROBIOLOGICAL WATER ANALYSIS The most important bacterial gastrointestinal diseases transmitted through water are cholera, salmonellosis and shigellosis. These diseases are mainly transmitted through water (and food) contaminated with feaces of patients. Drinking water can be contaminated with these pathogenic bacteria, and this is an issue of great concern. However, the presence of pathogenic bacteria in water is sporadic and erratic, levels are low, and the isolation and culture of these bacteria is not straight-forward. For these reasons, routine water microbiological analysis does not include the detection of pathogenic bacteria. However, safe water demands that water is free from pathogenic bacteria.

Coliforms are a broad class of bacteria found in our environment, including the feaces of man and other warm-blooded animals The presence of coliform bacteria in drinking water may indicate a possible presence of harmful, disease-causing organisms. They are defined as rod-shaped Gram-negative non-spore forming and motile or non-motile bacteria which can ferment lactose with the production of acid and gas when incubated at 35 – 37°C. Coliforms can be found in the aquatic environment, in soil and on vegetation; While coliforms themselves are not normally causes of serious illness, they are easy to culture, and their presence is used to indicate that other pathogenic organisms of feacal origin may be present.

A good bacterial indicator of fecal pollution should fulfill the following criteria: (1) exist in high numbers in the human intestine and feaces (2) not be pathogenic to humans (3) easily, reliably and cheaply detectable in environmental waters. (4) does not multiply outside the enteric environment (5) in environmental waters, the indicator should exist in greater numbers than eventual pathogenic bacteria

Bacteria Found In Surface Water Bacteria Disease/ infection Symptoms Aeromonas Enteritis Very thin, blood- and mucuscontaining diarrhea Campylobacter jejuni Campilobacteriose Flue, diarrhea, head- and stomachaches, fever, cramps and nausea Escherichia coli Urinary tract infections, neonatal meningitis, intestinal disease Watery diarrhea, headaches, fever, homiletic uremia, kidney damage Plesiomonas shigelloides Plesiomonas-infection Nausea, stomachaches and watery diarrhea, sometimes fevers, headaches and vomiting Typhus Typhoid fever Fevers Salmonella Salmonellosis Sickness, intestinal cramps, vomiting, diarrhea and sometimes light fevers Streptococcus (Gastro) intestinal disease Stomach aches, diarrhea and fevers, sometimes vomiting Vibrio Cholera Heavy diarrhea

Protozoa Found in Surface Water Microorganisms Disease Symptoms Amoeba Amoebic dysentery Severe diarrhea, headache, abdominal pain, chills, fever; if not treated can cause liver abscess, bowel perforation and death Cryptosporidi um parvum Cryptosporidiosis Feeling of sickness, watery diarrhea, vomiting, lack of appetite Giardiasis Diarrhea, abdominal cramps, flatulence, belching, fatigue Toxoplasm gondii Toxoplasmosis Flu, swelling of lymph glands With pregnant women subtle abortion and brain infections

Viral Sources of Waterborne Disease Hepatitis A: inflammation and necrosis of liver Norwalk-type virus: acute gastroenteritis Rotaviruses: acute gastroenteritis, especially in children Enteroviruses: many types affect intestines and upper respiratory tract Reoviruses: infects intestines and upper respiratory tract

SOIL MICROORGANISMS AND THEIR FUNCTIONS BACTERIA They are decomposers, eating dead plant material and organisms' waste. Do you know what soil smells like? Well actinomycetes, a unique type of bacteria, cause that smell, and it is a good sign of healthy soil. Actually, people have been smelling soil for many, many years as a way to judge if the land is good for planting [Nitrogen-fixing bacteria form symbiotic associations with the roots of legumes like clover and lupine, and trees such as alder and locust.

FUNGI § Fungi are organisms. They are not plants, nor are they animals. They group themselves into strings called hyphae. The hyphae then form groups called mycelium. § They are helpful but could also be harmful to soil organisms. Fungi are helpful because they have the ability to break down nutrients that other organisms cannot. § Fungi can attach themselves to plant roots. This is a good relationship called mycorriza. § The fungi help the plant by giving it those needed nutrients, and the fungi get food from the plant, the same food that plants give to humans. On the other hand, fungi can get food by being parasites, attaching themselves to plants or other organisms, but for selfish

§ Are organisms that have only one cell, and are microscopic, but larger than bacteria. § They are grouped by the ways they move: amoeba use a psuedo(fake) foot, ciliates have cilia (short hair) and move them very fast, and flagellates have one or moreflagella (whips) and move them very fast. § Protozoa eat bacteria which actually helps keep the bacteria population growing. Protozoa help other soil organisms and plants by releasing a usable form of nitrogen into the soil. They release the excess nitrogen in the form of ammonium (NH 4+). This usually occurs near the root system of a plant. § Another role that protozoa play is in regulating bacteria populations. Predatory nematodes may regulate populations of bacterial-and fungal-feeding nematodes, thus preventing over-grazing by those groups.

MICROBIOLOGY OF AIR Of all environments, air is the simplest one and it occurs in a single phase gas. Various layers can be recognized in the atmosphere up to a height of about 1000 km. The layer nearest to the earth is called as troposphere. This troposphere is characterized by a heavy load of microorganisms. The atmosphere as a habitat is characterized by high light intensities, extreme temperature variations, low amount of organic matter and a scarcity of available water making it a non hospitable environment for microorganisms and generally unsuitable habitat for their growth. Nevertheless, substantial numbers of microbes are found in the lower regions of the atmosphere. The study of these microbes in air is called as Aero Microbiology.

Disease caused by air borne microbes: Bacterial Diseases • Brucellosis: Brucella suis it is mainly an occupational disease among veterinarian, butcher and slaughter house workers. • Pulmonary Anthrax: Bacillus anthracis is the causative agent. Transmission is mainly by inhaling the dust contaminated by animal products. • Diseases Caused by Streptococcus Pyogenes: A number of diseases are caused by Streptococcus pyogenes which is mainly transmitted through air. Diseases Caused by Streptococcus pyogenes occur in the throat, skin, and systemically. • Rheumatic Fever: This is upper respiratory tract infection by S. pyogenes Characterized by inflammation and degeneration of heart valves. ·

• Streptococcal Pneumonia: It is of major occurrence among the bacterial pneumonia. Causative agent is Streptococcus pneumonia • Meningitis : Haemophilus influenzae causes meningitis in children between 6 weeks and 2 years of age. • Diptheria: Diphtheria is mainly contracted by children. Infection of the tonsils, throat and nose and generalized toxemia are the symptoms. The causative agent is Corynebacterium diphtheria • Tuberculosis: Pulmonary tuberculosis is a severe respiratory disease. Loss of appetite, fatigue, weight loss, night sweats and persistent cough are some of the symptoms. Causative agent is Mycobacterium tuberculosis • Legionellosis: It is a type of branchopneumonia. Legionella pneumophila is the causative agent. It occurs in natural water. At times it enters and proliferates in cooling tower, air cooler and shower bath. Spraying and splashing of water containing pathogen may produce aerosols which are disseminated in air.

It consists of many types. They are following • Cryptococcosis: Leads to mild pneumonitis. Causative agent is the yeast Cryptococcus neoformans. It is a soil saprophyte. Infection is acquired by inhalation of soil particles containing the causative agent. • Blastomycosis: Formation of suppurative and granulomatous lesions in any part of the body. Blastomyces dermatitis is the causative agent. It is a soil borne fungus and hence inhalation of soil particles containing the fungus produces the infection. • Coccidiodomycosis: Infection may not be apparent but in severe cases it is fatal. Usually infection leads to self-limited influenza fever known as valley fever or desert rheumatism. Causative agent of the disease is a soil fungus, Coccidioides immitis. Inhalation of dust containing arthrospores of the fungus leads to infection. • Aspergillosis: It is an opportunistic disease of human. Causative agent is Aspergillus fumigatus. Infection occurs through inhalation of spores.

Air Borne Viral Diseases: Air borne viral diseases are of different types. They are following, • Common Cold: It is the most frequent of all human infections. Characteristic symptom includes running noses. Rhinovirus is the causative agent. Droplets with nose and throat discharges from infected persons are the source. • Influenza: Symptoms of influenza are nasal discharge, head ache, muscle pains, sore throat and general weakness. Causative agents are orthomyxovirus. • Measles: Measles is the most common communicable human disease mainly affecting children. Symptoms are fever, cough, and cold and red, blotchy skin rash. Causative virus is morbillivirus. Source of infection is respiratory tract secretions in the form of droplets. • Mumps: It is a communicable disease and is a common childhood disease. It is characterized by painful swelling of parotid glands and salivary glands. Droplets containing infected saliva are the main source. • Adeno Viral Diseases: Adenoviruses cause acute self-limiting respiratory and eye infections. Adenoviruses are transmitted by airborne mode. Diseases include acute febrile pharyngitis, acute respiratory disease and adenovirus pneumonia.

SOURCES OF MICROORGANISM IN AIR: Quite a number of sources have been studied in this connection and almost all of them have been found to be responsible for the air micro flora. One of the most common sources of air micro flora is the soil. Soil microorganisms when disturbed by the wind blow, liberated into the air and remain suspended there for a long period of time. Man made actions like digging or ploughing the soil may also release soil borne microbes into the air. Similarly microorganisms found in water may also be released into the air in the form of water droplets or aerosols. Splashing of water by wind action or tidal action may also produce droplets or aerosols. Air currents may bring the microorganisms from plant or animal surfaces into air. The microorganisms are discharged out in three different forms which are grouped on the basis of their relative size and moisture content. They are droplets, droplet nuclei and infectious dust. It was Wells, who described the formation of droplet nuclei. This initiated the studies on the significance of airborne transmission.

§ Droplet: Droplets are usually formed by sneezing, coughing or talking. Each consists of saliva and mucus. Droplets may also contain hundreds of microorganisms which may be pathogenic if discharged from diseased persons. Pathogens will be mostly of respiratory tract origin. The size of the droplet determines the time period during which they can remain suspended. Most droplets are relatively large, and they tend to settle rapidly in still air. When inhaled these droplets are trapped on the moist surfaces of the respiratory tract. Thus, the droplets containing pathogenic microorganisms may be a source of infectious disease.

• Droplet Nuclei: Small droplets in a warm, dry atmosphere tend to evaporate rapidly and become droplet nuclei. Thus, the residue of solid material left after drying up of a droplet is known as droplet nuclei. These are small, 1 -4µm, and light. They can remain suspended in air for hours or days, traveling long distances. They may serve as a continuing source of infection if the bacteria remain viable when dry. Viability is determined by a set of complex factors including, the atmospheric conditions like humidity, sunlight and temperature, the size of the particles bearing the organisms, and the degree of susceptibility or resistance of the particular microbial species to the new physical environment. If inhaled droplet nuclei tend to escape the mechanical traps of the upper respiratory tract and enter the lungs. Thus, droplet nuclei may act as more potential agents of infectious diseases than droplets. Small droplets in a warm, dry atmosphere are dry before they reach the floor and thus quickly become droplet nuclei.

§ Infectious Dust: Large aerosol droplets settle out rapidly from air on to various surfaces and get dried. Nasal and throat discharges from a patient can also contaminate surfaces and become dry. Disturbance of this dried material by bed making, handling a handkerchief having dried secretions or sweeping floors in the patient's room can generate dust particles which add microorganisms to the circulating air. Most dust particles laden with microorganisms are relatively large and tend to settle rapidly. Droplets expelled during coughing, sneezing, e. t. c consist of saliva and mucus, and each of them may contain thousands of microorganisms. Occurs in a warm, dry climate, and before they reach the floor quickly become droplet nuclei. These are small and light, and may float about for a relatively long period. .

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