Gram stain causes gram-positive bacteria to stain red.Such an additional membrane is absent in gram-positive bacteria. The gram-negative bacteria have an additional outer membrane similar to the plasma membrane in structure.on the basis of this technique, bacteria are classified as gram-positive bacteria and gram-negative bacteria.
This technique distinguishes two types of cell wall construction in bacteria.They are commonly aquatic and pathogens.They are long and have a coil-shaped cell.They are gram-negative rod-shaped heterotrophic bacteria.They are pathogenic and cause diseases like bubonic plague and cholera.Usually, they are aerobic heterotrophs.They are gram-negative, rod-shaped bacteria.Sulphur bacteria, Nitrobacter, Nitrosomonas, etc. They play a great role in recycling nutrients like nitrogen, phosphorous, iron and sulphur.Chaemoautotrophs or chemosynthetic autotrophic bacteria oxidize various inorganic substances such as hydrogen sulphide, nitrates, nitrites, methane, and ammonia and use the released energy for their ATP production.Streptomyces, Mycobacterium, Actinomyces, etc. They produce commonly used antibiotics like streptomycin and tetracycline.They form branching filaments and produce spores.Rhizobium, Clostridium, etc.Įubacteria are divided into eight groups: They help bacteria in sexual reproduction and in pathogens to attach to host.ĭepending on the nature of the cell wall and the stain which they take up during Gram’s staining, they can be grouped into two categories: Gram-positive bacteria and Gram-negative bacteria. Some bacteria also contain very fine, short appendages on the cell surface and are called pili. The flagellum rotates like a propeller of a ship. The flagella are made up of protein flagellin. Their cell membrane contains lipids made up of glycerol ester lipids. They are characterized by the presence of a rigid cell wall made up of Peptidoglycan (Murein). There are thousands of different eubacteria or ‘true bacteria’. Their t-RNAĪnd r-RNA possess unique nucleotide sequences found nowhere else. They use pigment bacteriorhodopsin for photosynthesis. Most of the archaebacteria areĪutotrophs. In having a different cell wall structure and this feature is responsible for (thermoacidophiles) and marshy areas (methanogens).Īrchaebacteria differ from other bacteria Of the harshest habitats such as extreme salty areas (halophiles), hot springs These bacteria are special since they live in some The time of harshest conditions on the earth, they adapted themselves to live Someįossils found with these bacteria are 3,5 billion years old. Sub Kingdom Archaebacteria (Greek – archae – ancient): Sexual reproduction, mitosis, and meiosis are absent. The mode of reproduction is by fission or budding.The autotrophs may be photoautotrophs (e.g. They show different modes of nutrition like autotrophic, heterotrophic, parasitic or saprophytic.These organisms may be motile (using flagella) or non-motile.The cells are without chloroplasts, mitochondria etc.The organism may be unicellular as in eubacteria and filamentous as in cyanobacteria.The wall is rigid and composed of peptidoglycan.The nucleus is without a nuclear envelope, nucleolus, nucleoplasm, histone protein and true chromosomes.They are microscopic and prokaryotic, having a primitive type of nucleus.