Fungi

Fungi

·          The kingdom fungi, or mycetae is large and filled with a great variety and complexity ( more complex than bacteria )

·          Approximately 1000,000 species of fungi can be divided into two groups

1.      macroscopic fungi ( mushrooms, puffballs, gill fungi)

2.      microscopic fungi ( molds , yeast )

·          majority of fungi either uncicellular or colonial

·          not independent on light

·          can occupy dark habitats

·          can grow in any direction

·          can invade interior of the substrate with absorptive filaments.

What they look like ( morphology )

At a cellular ( microscopic ) level ,typical eukaryotic cell,with thick cell walls , consisting of a nucleus containing chromosomes inside a membrane. The surrounding cytoplasm contains mitochondria and ribosomes.

1.      Yeasts are single cell that form buds and pseudohyphae.

2.      Molds are filamentous fungi and form hyphae ( long , tubular , filaments that can be septate or non-septate and grow in a network called a mycelium )

3.      some fungi ( mushrooms ) produce mutlicellular structures such a fleshy fruiting bodies

Where they're found

·          Fungi usually grow best in environments that slightly acidic ( a pH measurement of 5 or so; a pH of 7 is neutral ).

What they eat

·          Heterotrophic

·          Majority are harmless saprobes and a few are parasites.

Classification

Fungi are divided into four groups

1. YEAST____round / oval cells which reproduce by budding.

e.g Cryptococcue neoformans

2. YEAST-LIKE Fungi _____like yeast , most will reproduce by budding. But some form filaments, e.g Candida albicans
3. FILAMENTOUS FUNGI______These grow as filaments ( hyphae ) which interweave into a mesh ( the mycelium ) : they reproduce by asexual spores e.g Aspergillus, and ring worm fungi.
4. DIMORPHIC FUNGI _______these grow into two forms, according to their situation: as yeast in the body but form mycelium in the environment or in the culture e.g Blastoomyces and Histoplasma.

MYCOSES

Fungi may be divided into four groups and the disase which may be caused, may be further subdivide into these causing superficial or deep/systemic infections.

FUNGAL INFECTIONS

FUNGUS TYPE	Superficial	DEEP
Yeast/yeast like Filamentous Dimorphic	Candida Dermatophytes ( tinea )	Candida Crytococcus Aspergillus Mucor* Rhizopus* Histoplasma Blastomyces Coccidiodes Paracoccdioides sporothrix

*zygomycetes

ECONOMIC IMPORTANCE OF FUNGI:

1. SOIL FERTILITY

Together with bacteria, they are the important organisms which bring about the decay of organic matter and the formation of humus.

2. MEDICINE

A number of fungi are used for producing antibodies which are antimicrobial. Antibiotics usually act by killing germs or preventing their reproduction.

3. FOOD

Some fungi, e.g truffles, puff balls and certain mushrooms are edible and considered as dilicaies. It is used in the making of bread. Yeast is used in breweries for making alcohol drinks by fermentation.

HARMFUL FUNGI

1. PLANT DISASES

A large number of plants disease are caused by fungi e.g potato, blight , wilt , rots , smuts, mildew , leaf spot, rust , scab.

2. SPOILAGE

Fungi destroywoooden building ( dry not ) stroed cereals,fruits and vegetables, leather goods , cotton etc

3. HUMAN DISEASE

Fungi cause a number of superficial skin disease in man e.g. athlete's foot and some allergies.

ECONOMIC IMPORTANCE OF YEASTS

Yeasts are unicellular fungi. Motly they reproduce asexually by budding. The fermentation of sugar to alcohol by yeasts under anaerobic conditions is the process that is used is breweries the most important yeasts in the process is saccharomyces cerevisiae.

·           In the making of bread,yeast causes the production of CO2 by the fermentation of sugar, this results in the raising of the dough and is responsible for the porous nature of bread

·           Some fungi e.g. truffers, puff balls, and certain mushrooms are edible and considered as delicacies. Yeast also has a high content of vitamins b.

·           Other yeast are important pathogens and cause disease such as thrush and Cryptococcus, one of them candida, cause a common vaginal infection.

·           Yeasts has also become very important in genetic research over the past few decades

BENIFICIAL AND HARMFULL BACTERIA

BENIFICIAL BACTERIA:

1. DECOMPOSERS

They bring about the decomposition of dead or decaying plant or animal material or humus with the help of enzymes and are thus called decomposers, they not only solve the problem of eliminating.

2. ALIMENTARY CANAL BACTERIA

In herbivores, they help digest cellulose with the help of enzyme cellulose present in colon or appendix. In man, these bacteria produce vitamin B group, plus vitamin H and K.

3. INDUSTRIAL BACTERIA

Industrial processes like tobacco curing, vinegar , butter , cheese , alcohol manufacture, linen and leather making involve bacterial which help in controlling other bacteria

4. GENETICALLY ENGINEERED BACTERIA

E. coli has been programmed to make up for growth deficiencies and insulin for the diabetics

5. MEDICAL BACTERIA

Many antibiotics have been obtained from bacteria which help in controlling other bacteria.

HARMFULL BACTERIA

1. PATHOGENIC BACTERIA

They cause different disease of man and animal and plant, man's disease including. Typhoid , tetanus , tuberculosis , diphtheria etc.

2. FOOD SPOILING BACTERIA

They are responsible for spoilage of food by fermentation putrefaction and decomposition.

TERMINOLOGIES

1. Cleaning is removal of contamination such as dirt
2. Disinfection is the use of physical process or chemical agents to destroy vegetative pathogens, but not bacterial endospores
3. Sterilization is a process that destroys or removes all viable microorganisms, including viruses any material that has been subjected to this process isn said to be sterile
4. Sanitation is any cleansing technique that mechanically removes microorganism to reduce the level of contaminants
5. Disinfectant is a chemical agent to destroyer vegetative pathogens, but not bacterial endospores ( disinfectant is normally used only on inanimate object )
6. antiseptics are chemical agents. Applied directly to exposed body surface ( skin and mucous membranes ) wound, and surgical incisions to destroy or inhibit vegetative pathogen
7. Sanitizer is a compound such as soap or detergent that mechanically remove microorganisms
8. Bactericidal is a chemical that destroys bacteria except for thos in the endospore stage
9. Fungicidal is a chemical that can kill fungal spores, hyphase, and yeast
10. Viruscide is any chemical known to inactive viruses, especially on living tissue
11. Sporicide is a chemical agent capable of destroying bacterial endospores
12. Germicide is any chemical agent that kills pathogenic microorganisms
13. Bacteriostatic agent prevents that growth of bacteria on tissues or on objects in the environment
14. Degermation is a process, involves scrubbing the skin or immersing it in chemicals, or both.

·           It emulsifies oil that lies on the outer cutaneous layer

·           Mechanically removes potential pathogens on the outer layer of the skin

Examples

1.      Surgical hand scrub

2.      application of alcohol wipes to the skin

3.      cleansing of wound with germicidal soap and water

Toxin

" a specific chemical product off microbes. Plants and some animals that is poisonous to other organisms"

TYPES

1. EXOTOXIN
2. ENDOTOXIN

MAIN FEATURES OF EXOTOXIN AND ENDOTOXIN

PROPERTY	EXOTOXIN	ENDOTOXIN
SOURCE	G+ve & G-ve species	G-ve species
SECRETED FROM CELL	yes	No component of cell call
CHEMISTRY	Polypeptide	lipopolysaccharide
TOXICITY	high	low
Clinical EFFECTS	Various effects	Fever.shock
ANTIGENICITY	Induces high titer antibodies called antitoxins	Poorly antigenic
VACCINES	Toxoids used as vaccines	No toxoids formed and no vaccines
HEAT STABILITY	Destroyed rapidly at 60 C	Stable at 100 C for 1 hour
TYPICAL DISEASE	Tetanus , botulism , diphtheria	Sepsis