General Characteristics of Bacteria ::
Bacteria are found everywhere in air water vegetables soil animals birds human beings and various other articles like foods and excreta They are living bodies that need particular type of food oxygen water certain degree of temperature and moisture In short they need a favourable atmosphere to thrive
Food is obtained from the surrounding medium in dissolved form It consists of carbohydrates proteins and fats with minerals vitamins and water if the microbes are deprived of their food and water they generally die though some can live without food and water for a long time
Oxygen is a must to many but not to all the microbes Thus there are aerobes anaerobes and facultative aerobes Aerobes need oxygen anaerobes can grow without oxygen and facultative one can live with or without oxygen
Temperature :; Most microbes grow between 37.C and 38. C They die at 69.C But few spores survive In cold they donot die but lie dormant and grow again when environment is warm Thus in ice they live latent life but in boiling water most of them die If fractional sterilisation is done under high pressure of steam microbes their spores and viruses will all die
Reaction :: They thrive best in neutral or mild alkaline media But some also live in acid media Each type has special medium and if it is changed they die
Reproduction : They reproduce very fast by fission or divide and multiply One bacterium can multiply to millions and billions in one day They also die as fast as they grow
Some bacilli from spores in unfavourable conditions Spores are hard dry and resistant They generally donot die in heat cold or dry surrounding when conditions are favourable they again come to normal vegetative form and grow Bacillius of tetanus forms spores
Microbes though minute bring about vast changes in nature They may also ferment putrify and nitrify various substances These microbes are called saprophytes
There are microbes that are useful to human beings for example some vitamin producing microbes are in our intestine Those affecting human beings adversely and producing diseases are called pathogens we are to study them so that we can prevent their growth or kill them and cure the infection
Protozoa ::
They are unicellular animal organisms e.g. Entamoeba histolytica producing amoebic dysentery plasmodium vivax producing malaria
Moulds and Fungi ::
These are vegetative cells giving rise to fungal diseases e.g. monilia giving rise to moniliasis
Worms or helminths ::
These are the triploblastic animals e.g Round worms Tape worms Hook worms Thread worms Liver flukes Guinea worm etc
0 Comments