Control of Microbial Growth Gabriella Gita Febriana NIM : 10406002
Control of Microbial Growth • Pasteur : invisible microbes could cause disease • Lister : found the modern antiseptic for surgery • Used a solution of carbolic acid (phenol) Introduction Louis Pasteur Joseph Lister
Control of Microbial Growth Control of Microbial Growth • To INHIBIT or PREVENT growth of microorganisms • Affected in 2 basic ways : • By killing microorganisms (cidal agents) • By inhibiting the growth of microorganisms (static agents) • Sterilization : complete destruction or elimination of all viable microorganisms in a sterilized substance
Control of Microbial Growth Methods of SterilizationI. Heat • Incineration • Burns organisms and physically destroys them • Boiling • 100ᵒC, 30 minutes kills everything except endospores • Intermitent boiling (>6hours) to kill endospores
Control of Microbial Growth Methods of SterilizationI. Heat (cont.) • Autoclaving • Most effective and efficient • Usual standard temperature/pressure : 121ᵒC/15psi for 15 minutes • Using steam under pressure as the sterilizing agent • Thermal Death Time • Dry heat • Not as effective as moist heat
Control of Microbial Growth Methods of SterilizationII. Irradiation • Ultraviolet • Causes adjacent thymine molecules on DNA to dimerize inhibiting DNA replication • Gamma Radiation • Break chemical bonds by interacting with the electrons of atomic constituents • Highly effective in killing microorganisms
Control of Microbial Growth Methods of SterilizationII. Irradiation (cont.) • Electron Beam Radiation (e-beam radiation) • Low penetration and high dose rates. • Similar to Gamma radiation
Control of Microbial Growth Methods of SterilizationIII. Filtration • Exclusion of all cells in a liquid or gas • For sterilization of solution which would be denatured by heat. eg: antibiotics, injectable drugs, amino acids, vitamins, etc. Millipore membrane
Control of Microbial Growth Methods of SterilizationIV. Gas & Chemicals • Ethylene oxide (ETO) • Most commonly used form of chemical sterilization • Reacts with amino acids, protein, and DNA to prevent microbial reporduction • Used for cellulose and plastic irradiation
Control of Microbial Growth ETO Sterilization Gas Chamber
Control of Microbial Growth Methods of SterilizationIV. Gas & Chemicals (cont.) • Ozone Sterilization • Uses oxygen that is subjected to an intense electrical field that separates oxygen molecules into atomic oxygen. • Used as disinfectant for water and food Ozone fogger Ozone sterilizer
Control of Microbial Growth Methods of SterilizationIV. Gas & Chemicals (cont.) • Low Temperature Gas Plasma (LTGP) • Alternative to ethylene oxide • Uses small amount of hydrogen peroxide (H2O2) energized with radio frequencies waves into gas plasma • Generation of free radicals destroy microorganisms
Control of Microbial Growth Non Sterilizing MethodsI. Application of Heat • Boiling • Inactivates viruses • Giardia cysts can survive in this process • Pasteurization • Use of mild heat to reduce the number of microorganisms in products or foods. ex: milk • Milk 63ᵒC, 30 min (batch method) or 71ᵒC 15 sec (flash method) • Ultrapasteurization • Milk is heated to temperature of 140ᵒC
Control of Microbial Growth Non Sterilizing MethodsII. Low Temperature • Refrigeration & Freezing • non bactericidal • most foods are preserved against microbial growth in the household freezer
Control of Microbial Growth Non Sterilizing MethodsIII. Drying • Removal of H2O • often used to preserve foods • removal of water heat, evaporation, freeze-drying, and addition of salt or sugar
Control of Microbial Growth Non Sterilizing MethodsIV. Irradiation • UV, X-ray, Gamma Radiation • destroys microorganisms • fruits and vegetables are irradiated to increase their shelf life up to 500 percent • According to the FDA, irradiation does not make food radioactive, nor does it noticeably change taste, texture, or appearance.
Control of Microbial Growth Control of Microbial Growth by Chemical Agents • Antimicrobial Agents • chemicals that kill or inhibit the growth microorganisms • may be of natural or synthetic origin, and they may have a static or cidal effect on microorganisms.
Control of Microbial Growth Types of Antimicrobial Agents • Antiseptics • microbicidal agents harmless enough to be applied to the skin and mucous membrane • should not be taken internally • Disinfectants • agents that kill microorganisms, but not necessarily their spores • not safe for application to living tissues • used on inanimate objects
Control of Microbial Growth
Control of Microbial Growth
Control of Microbial Growth Types of Antimicrobial Agents (cont.) • Preservatives • static agents used to inhibit the growth of microorganisms • nontoxic
Control of Microbial Growth
Control of Microbial Growth Types of Antimicrobial Agents (cont.) • Chemoterapeutic Agents (synthetic antibiotics) • antimicrobial agents of synthetic origin useful in the treatment of microbial or viral disease • Ex : sulfonilamides, isoniazid, ethambutol, AZT, nalidixic acid and chloramphenicol • Antibiotics • antimicrobial agents produced by microorganisms that kill or inhibit other microorganisms • low molecular-weight (non-protein) molecules produced as secondary metabolites, mainly by microorganisms that live in the soil
Control of Microbial Growth Types of Antimicrobial Agents (cont.) • Semi-synthetic Antibiotics • molecules produced by a microbe that are subsequently modified by an organic chemist to enhance their antimicrobial properties
Control of Microbial Growth
Control of Microbial Growth
Control of Microbial Growth
Control of Microbial Growth Antimicrobial Agents in Treatment of Infectious Diseases • Selective Toxicity • acts in some way that inhibits or kills bacterial pathogens • has little or no toxic effect on the animal taking the drug • Spectrum of Action • Narrow spectrum • Broad spectrum • Limited Spectrum
Control of Microbial Growth Mode of Actions • Cell wall synthesis inhibitor • Beta-lactams antibiotics • Natural Penicillins • Semi-synthetic penicillins • Clavulanic Acid • Cephalosporins • Bacitracin • Cell membrane inhibitor • Polymyxin
Control of Microbial Growth Mode of Actions (cont.) • Protein synthesis inhibitor • Tetracyclines, e.g : tetracycline, chlortetracycline, doxycycline • Chloramphenicol • Macrolides, e.g : erythromycin, azythromycin • Aminoglycosides, e.g : streptomycin • Kanamycine • Gentamicin, Tobramycin
Control of Microbial Growth Mode of Actions (cont.) • Effects of Nucleic Acids • Quinolones, e.g : nalidixic, ciprofloxacin • Rifamycins, e.g : rifampicin • Competitive inhibitors • Sulfonamides, e.g : sulfanilamide, gantrisin and trimethoprim
Control of Microbial Growth Bacterial Resistance to Antibiotics • Inherent (natural) resistance • Acquired resistance • Vertical evolution • Horizontal Gene Transmission (HGT) • Bacteria exchange genes by 3 process : • Conjugation • Transduction • Transformation
Control of Microbial Growth Alternative to Antibiotics • Phage Therapy • use of lyticbacteriophages to treat pathogenic bacterial infections • Benefit : derived from the observation that bacteriophages are much more specific than most antibiotics that are in clinical use • Negative effect : phages are self-replicating in their target bacterial cella single, small dose is theoretically efficacious
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