how to reduce microbial activities.

1. Control of Microorganisms
Submitted By:-
Saumya Rawat (19PBT002)
Shubhangini Singh (19PBT003)
Ilika Kaushik (19PBT004)
Purnima (19PBT005)
Rajeshwari Mishra (19PBT007)
M.Tech Biotechnology, 1st Sem,
SoBT, GBU.
Submitted To:-
Dr. Jitendra Singh Rathore
Sir
Asst. Professor
SoBT, GBU.

2. Index
S.No. Contents
1. Sterlization, Disinfection and Asepsis
2. Physical Method for Control of Microorganism
3. Chemical Method for Control of Microorganism
4. Antibiotics, Antifungal and Antiviral Drugs
5. Biological Control by Microorganisms

3. Sterilization, Disinfection and Antisepsis
• Sterilization: Process by which all living cells, spores, and
acellular entities are either destroyed or removed from
an object or habitat. A chemical agents which is used for
sterilization is called a sterilant.
 Physical agents: Heat: Dry (Incineration, dry oven) &
Moist (Steam under pressure); Radiation: X-ray, cathode,
gamma.
 Chemical agents: Gases (ethylene oxide,
betapropiolactone); Liquids
• Disinfection: Process of killing, inhibiting, or removing
microorganisms that may cause disease. Thus,
substantial reduction of the total microbial population
and destruction of potential pathogens. Chemical agents
used for disinfection are called disinfectants, that do not
necessarily sterilize an object because viable spores and
a few microorganisms may remain.

4.  Physical agents: Moist heat (boiling water &
pasteurization); Radiation (Ultraviolet radiation).
 Chemical agents: Gases (chlorine dioxide); Liquids
(phenol, alcohols, quaternary ammonium compounds).
• Antisepsis: The destruction or inhibition of
microorganisms on living tissue, thus, preventing
infection. Antiseptics are chemical agents applied to
tissue to prevent infection by killing or inhibiting
pathogen growth, hence, reduce the total microbial
growth.
 Chemical agents: Liquids (phenol, alcohols, cationic
detergents).
• Substances that kill organisms often have the suffix –
cide, and that prevent microbial growth have the suffix –
static.

5. CHEMICAL METHODS OF
STERILIZATION
• Few chemical agents achieve sterility.
• Types:
• Phenols: carboxylic acid
• Phenolic: cresols (lysol)
• Bisphenol: Hexachlorophene (pHisoHex), hospitals, surgeries, nurseries , triclosan
(toothpaste, antibacterial soaps, etc.)
• Halogens :Effective alone or in compounds.
• Chlorine :Oxidizing agent . Widely used as disinfectant . Forms bleach
(hypochlorous acid) when added to water. Broad spectrum, not sporicidal (pools,
drinking water).
• Iodine: More reactive, more germicidal. Alters protein synthesis and membranes.
Tincture of iodine (solution with alcohol) wound antiseptic. Iodophores: combined
with an organic molecule ,iodine detergent complex (e.g. Betadine). Occasional
skin sensitivity, partially inactivated by organic debris, poor sporicidal activity.
• Alcohol: Ethyl (60 – 80% solutions) and isopropyl alcohol. Denature proteins,
dissolve lipids . No activity against spores and poorly effective against viruses and
fungi . Easily inactivated by organic debris . Also used in hand sanitizers and
cosmetics.

6. • Heavy metals: Oligodynamic action: toxic effect due to metal ions combining with
sulfhydryl (—SH) and other groups. Proteins are denatured.
• Mercury (HgCl2, Greeks & Romans for skin wounds).
• Copper: against chlorophyll containing organisms(algae).
• Silver (AgNO3 ): Antiseptic for eyes of new-borns .
• Zinc (ZnCl2 ) in mouthwashes, ZnO in antifungal in paint.
• Aldehydes (alkylating agents) : Inactivate proteins by cross-linking with functional
groups (–NH2 , –OH, –COOH, –SH). Glutaraldehyde: Sterilant for delicate surgical
instruments (Kills S. aureus in 5, M. tuberculosis in 10 min). Formaldehyde: Virus
inactivation for vaccines ,preserve biological specimen.
• Chemical Sterilants for heat sensitive material : Denature proteins by replacing
functional groups with alkyl groups, e.g.: Ethylene oxide

7. Physical Method for Control of
Microorganisms.
• Heat and other physical agents are normally used to control
microbial growth and sterilize objects.
Physical
Methods.
Heat
Low
Temp.
Filtration
Radiation

8. • Heat-
 Thermal Death Point
(TDP)
 Thermal Death Time
(TDT)
 Decimal Reduction Time
(DRT)
 Moist Heat
 Dry Heat
 Pasteurization
• Filtration-
 Depth Filters
 Membrane Filters
 HEPA Filters
• Low Temperatures-
 Refrigeration
 Freezing
 Flash Freezing
 Slow Freezing
• Radiation-
 Ionization Radiation
 Non-Ionization Radiation

9. Antibacterial Drugs
• Sulfonamide or sulfa drugs are structural analogues to metabolism and inhibit folic acid
metabolism.
• Qunilones are synthetic drugs that contains 4- ring qunilones rings. It inhibits by acting on DNA
Gyrase & bacteriocidal in nature.
• Penicillin is derivative of 6- aminopenicillanic acid having lactame ring. It must be
administered parenterally because it is destroyed by stomach acid.
• Cephalosporin are structurally similar to penicillin. Broad spectrum drug, frequently given to
penicillin allergic patients.
• Tetracyclines have a common 4- ring structure to which variety of side chains are attached. It
inhibits protein synthesis( by inhibiting the binding of amino acyl tRNA).
• Aminoglycoside Antibiotics e.g. Streptomycin, kanamycin etc. are synthesised by
Streptomyces. Interfere with protein synthesis.
• Erythromycine & other microlides binds with 23sRNA of 50s ribosomal unit. Used for penicillin
allergic patients.
• Vancomycin & Teicoplanin are glycopeptide antibiotics. These are bactericidal & are orally
administered.
• Chlorampheniccol inhibits peptide transferase. It is bacteriostatic in nature. It is toxic and
have side effects.

10. • These antibiotics use different mechanism of action; inhibition of cell wall
synthesis, inhibition of protein synthesis, inhibition of nucleic acid & cell
membrane and antimetabollits.
• Microorganisms uses various mechanisms of drug resistance to save
themselves; prohibiting drug access, use of efflux pump, drug
modification, target modification & alternating the pathway.
Antifungal and Antiviral Drugs
• Antifungal Drugs are toxic and have side effects as have low therapeutic
index. It is less effective as eukaryotic cells are more similar to human
cells.
• Antiviral Drugs disrupts either critical stages (entry, replication &
spreading) or synthesis of virus- specific nucleic acid.e.g., Amantacline,
rimantadine etc.

11. Biological Control by
Microorganisms.
• Biocontrol is the reduction of undesirable species
population by natural enemies and usually involves
an active human role
• Biocontrol microbes control their target species
through a multitude of biological interactions. The
most common are competition for resources,
causing disease in the target species
(pathogenesis), production of allelochemicals and
influencing crop plants.

12. • Bacteria, fungi and viruses can all act as biocontrol
agents due to the large diversity of target species and
the variety of methods of action. Important examples of
microbial biocontrol agents include:-
 Bacillus thuringiensis,
 Fluorescent Pseumonads,
 Rhizobium etli
 Beauveria bassiana.
 Caudovirales
In agriculture, microbial biocontrol agents are usually
referred to as biopesticides.