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These are the characteristics of Gram-negative bacteria
- Cytoplasmic content is present means periplasm is present.
- The much thicker Peptidoglycan layer is present in gram-negative than gram-positive bacteria.
- The outer membrane of gram-negative contains LPS ( lipopolysaccharides) that contain, core polysaccharides, Lipid- A, and O- Antigen).
- Porins present in the outer membrane, that act as pores for some of the molecules.
- Space is filled with a concentrated gel-like between the cytoplasmic membrane and outer membrane.
- S layer in gram-negative is directly attached to the outer membrane instead of peptidoglycan
- If flagella present in ram negative then flagella have four supporting rings instead of two
- Lipoteichoic acid or Teichoic acids are absent.
- Lipoproteins are attached to the polysaccharide backbone
- Some of them contain Braun’s lipoprotein, which acts as a link between the outer membrane and the peptidoglycan chain by a covalent bond
- Very few of them contains spores
These are the characteristics of Gram-positive bacteria
- Cytoplasmic lipid membrane in gram-positive bacteria.
- The thick peptidoglycan layer also presents in the gram-positive membrane.
- Techioc Acis and lipoids are present, which act as chelating agents, and also helps in adherence.
- In gram-positive bacteria, Peptidoglycan chains are cross-linked to form rigid cell walls by a bacterial enzyme.
- periplasm membrane is present in it but in a very small amount than that in gram-negative bacteria.
- Only a few species of gram-positive bacteria have a capsule.
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Commercial use of Non-Pathogenic microorganisms
Many streptococcal species are nonpathogenic and form part of the human normal flora of the mouth, skin, intestine, and upper respiratory tract. They are utilized also in the industry for producing Swiss cheese.
Many low pathogenic species of corynebacterium are utilized in industrial production of amino acids, nucleotides, bioconversion of steroids, hydrocarbons degradation, enzymes of a different kind production, etc.
Many Bacillus species of gram-positive bacteria secrete different kinds of enzymes.
- Bacillus amyloliquefaciens is the source of a natural antibiotic protein ribonuclease, alpha-amylase used in starch hydrolysis, the protease subtilisin used with detergents, and the BamH1 restriction enzyme used for research in DNA.
- C. thermocellum can be used in industry as lignocellulose waste and produce ethanol, thus making it a major source for use in the production of ethanol. It is anaerobic and is thermophilic, which reduces cooling costs.
- C. acetobutylicum, also known as the Weizmann organism, was first used by Chaim Weizmann to produce acetone and biobutanol from starch in 1916 for the production of gunpowder and TNT.
- C. botulinum produces a potentially lethal neurotoxin that is used in a diluted form in the Botox drug. It is also used to treat spasmodic torticollis and provides relief for approximately 12 to 16 weeks.
- The anaerobic bacterium C. ljungdahlii can produce ethanol from single-carbon sources including synthesis gas, a mixture of carbon monoxide and hydrogen that can be generated from the partial combustion of either fossil fuels or biomass.
Gram-positive and Gram-negative bacteria with commercial uses