KINGDOM MONERA

                            

The kingdom monera is comprised only of bacteria. Not only are bacteria extremely small but they are structurally the simplest and most ancient of all organisms. All the bacteria are unicellular,consisiing of just single prokayotic cell.Prokaryotes lack many of the cellular structural  characteristics of more complex eukaryotic cells , including membrane-bound organelles and nuclei.

                            The bacteria are the most numerous of all the organisms.Bacteria have evolved an amazing diversity of means of acquiring the resources they need to live and reproduce.This remarkable diversity has enabled the bacteria to inhabit virtually every known environment on earth from the hot sulphur springs of Yellowstone to the glacial ice of the Arctic to the depths of the ocean floor.There are two major group of Monerans - ARCHAEBACTERIA(ancient bacteria) and EUBACTERIA(true bacteria).Eubacteria are further of  two types- BACTERIA & CYANOBACTERIA. Some other groups of Monerans include MYCOPLASMA , RICKETTSIAE  &  ACTINOMYCETES.

NUTRITION IN BACTERIA

The biologist recognise two main types of nutrition :

(a) AUTOTROPIHIC : organisms livces entirely on inorganic compounds.
(b) HETEROTROPHIC : organism thrives on organic substances.

Depending upon the energy source , the orgnisms are again classified into two categories :

(c) PHOTOTROPHS or PHOTOSYNTHETIC : these utilise light as the energy source.
(d) CHEMOTROPHS or CHEMOSYNTHETIC : these utilise chemical energy.

On the basis of source of electron,two nutritional types are:

(e) ORGANOTROPHS : source of electron is an organic compound.
(f) LITHOTROPHS : source of electron is an inorganic compound.

In view of all the above, four nutritional categories emerge out which are :

• PHOTOSYNTHETIC AUTOTROPHS or PHOTOLITHOTROPHS :these photosynthetic bacteria use inorganic electron donor such as H2S,H2,sulphur compound etc.these contain bacteriocholorophyll.Eg: CHLOROBIUM,CHROMATIUM.
• PHOTOSYNTHETIC HETEROTROPHS or PHOTO-ORGANOTROPHS : these use organic compunds as electron donors,such as organic acids,alcohols , etc. Eg : RHODOSPIRILLUM,RHODOPSEUDOMONAS.
• CHEMOSYNTHETIC AUTOTROPHS or CHEMOLITHOTROPHS : some autotrophic aerobic bacteria assimilate CO2 witnout using radiant energy. these obtain energy by the oxidation of some inorganic compunds e.g.: nitrifying bacteria(NITROSOMONAS,NITROBACTER) , sulphur bacteria(BEGGIOTA),iron bacteria(FERROBACILLUS),hydrogen bacteria(HYDROGENOMONAS)
• CHEMOSYNTHETIC HETEROTROPHS or CHEMO-ORGANOTROPHS :  these heterotrophic bacteria use organic compounds as substrates e.g.:ESCHERICHIA COLI.