Pasteurization, named after Louis Pasteur as he was the pioneer of the process Pasteurization, involved mild heat treatment applied to grape must and juice. This process inhibits or eliminates bacteria and yeast, preventing microbial spoilage and oxidation risks.

While Pasteur pasteurized wine, pasteurization of milk was experimented by German chemist “Franz von Soxhlet”. 

As people transitioned from rural to urban living, milk emerged as a significant source of foodborne illnesses due to the complexities of longer and more intricate supply chains. The historical shift led to raw milk reaching consumers after extended periods, sometime days or weeks old, contributing to a surge in childhood deaths from contaminated milk by the 20th century. This alarming public health concern prompted the global adoption of milk pasteurization as a crucial measure to mitigate hazards associated with its consumption.

Pasteurization, a widely employed method for food processing, involves the application of high heat to eliminate specific microorganisms from food substances. Controlled temperatures below 100℃ are utilized on chosen food samples to effectively destroy harmful microorganism.

In terms of benefits, pasteurization does not produce a substantial undesirable cooked flavour post treatment. In other words, the natural taste of food substance remains largely unaltered as no chemical additives are needed during the heating process. The removal of harmful microorganism from food substances result in a considerable extension of the shelf life of the processed products. 

Other benefits of pasteurization is witness in the deactivation of enzymes that are found in various food substance. For example, milk is well endowed with enzymes like lipase and phosphatase. These enzymes usually lower the overall quality of milk. Pasteurized milk has a higher market value than the non-pasteurized milk.      

Disease prevented by pasteurization can include tuberculosis. Brucellosis, diphtheria, scarlet fever, and Q- fever. It also kills the harmful bacteria such as Salmonella, Listeria, Yersinia, Staphylococcus aureus, and Escherichia coli.

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The best possible configuration for MFC is still being researched, and in order to improve its efficiency, new electrode materials and more precise protons exchange membranes are presently being created. Small cells paired in series appear to have more capacity over larger reactor sizes. At present, the primary obstacles to the widespread use of MFC are the expensive price of raw materials and the inadequate buffering ability of home wastewater. This is the reason why MFC has not yet found industrial use. However, laboratory tests have successfully proven the viability of utilising MFCs to treat domestic wastewater, yielding power densities with roughly 420-460 mW m−2 and COD removal rates of up to 50%. Recently, an MFC fed using artificial waterways able to remove C and N.

In this instance, carbon oxidation and SND were carried out independently in the cathode compartment. This setup minimised the COD requirements while optimising the C source. Furthermore, the MFC technique can function very well at moderate COD/N ratios because denitrification leverages the charged particles obtained from the independent combustion of organic materials present in the effluent. As a result, less external C-source supply is needed. Thus, the findings documented in the literature demonstrate that it is feasible to remove N from MFCs while producing energy, thereby advancing the prospect of self-sufficient WWTPs.

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CHARACTERISTICS OF TYPING METHODS:

1. TYPEABILITY: It refers to the ability of the method to type and generate a result for each isolate to be tested.

2. REPRODUCIBILITY: It refers to the ability of the method to produce similar results when tested repeatedly in different laboratory centres.

3. DISCRIMINATIVE POWER: It refers to the ability of the method to generate distinct units of information making a clear differentiation between the types at the subspecies level.

4. PRACTICALITY: It refers to ease of use and interpretation, cost and affordability.

CLASSIFICATION OF MICROBIAL TYPING:

• Typing methods are broadly categorized into 2 types which are as follows:

1. Phenotypic method: detects characteristics expressed by microorganism.

2. Genotypic method: direct DNA- based analysis of chromosomal or extrachromosomal genetic elements.

PHENOTYPIC METHODS:

1. BACTERIOPHAGE TYPING:

Strains of an organism can be further differentiated into subspecies level based on their sensitivity to bacteriophages. It is obsolete now.

2. BACTERIOCIN TYPING:

Bacteriocin is an antimicrobial- like proteinaceous substance produced by one bacterium that inhibits other strains of the same or other closely related bacteria.

Example: Colicin secreted by Gram -negative bacterium and megacine secreted by Gram positive bacterium.

3. BIOTYPING:

It refers to intra-species classification based on different biochemical properties of organisms.

4. ANTIBIOGRAM TYPING:

It refers to differentiating organisms into individual groups based on their resistance pattern to different antimicrobials.

5. SEROTYPING:

It refers to a typing method based on the antigenic properties of an organism.

GENOTYPIC METHODS:

• It includes the following methods:

1. Restricted Fragment Length Polymorphism(RFLP)
2. Ribotyping
3. Pulse Field Gel Electrophoresis(PFGE)
4. Amplified Fragment Length Polymorphism(AFLP)
5. Sequencing based methods which include Nucleotide sequencing and Whole genome sequencing.

• In general, genotypic methods are more reliable and have better reproducibility and discriminative power than phenotypic methods. They are expensive in nature.
• It is used to determine multidrug resistant pathogens.

APPLICATIONS OF MICROBIAL TYPING:

• It is an important tool for hospital microbiologists and epidemiologists.
• It is used to determine relatedness between different microbial strains of same species and thereby it helps to:

1. Investigate an outbreak.
2. Determine the source and route of infection.
3. Differentiate virulent strains from avirulent strains of the same species.
4. Differentiate between recurrence and infection with new strain.
5. Trace cross infection.

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Elie Metchnikoff was the first scientist to conceptualize the term ‘probiotic’. He was Russian Nobel Prize Winner and known as the FATHER OF MODERN IMMUNOLOGY.

Probiotic term was coined in 1965 by Lily and Stillwell.

• DEFINITION:

Probiotic word comes from Greek word – ‘PRO’ means ‘before,forward’ and ‘BIOS’ means ‘life’. Probiotic means life promoting beneficial bacteria.They are known as Effective Microbiota or Friendly Bacteria’. WHO states that a probiotic is a live microorganism which when administered in adequate amount provides a health benefit to host.These bacteria are normal inhabitants of intestine and are normally found in healthy gut of all humans. Lactic acid bacteria(LAB), Bifidobacterium are most types of microbes used as probiotic,but certain yeast and bacilli may also be used.

• COMPOSITION OF PROBIOTICS:

LAB, Streptococci and Bifidobacterium constitute the probiotics currently used preparation.They are harmless and important components of Gastrointestinal microflora.

1. Lactobacilli

Fermented food and dairy products(yogurt) contains LAB. Three species of LAB are known to be used in probiotic preparation i.e. L.plantarum, L.casei and L.sporogenes. They help in digestion of lactose products.

2. Bifidobacterium

It is common intestinal flora found in infants. Known species are B.longum, B.infantis, B.breve

They are known to protect intestinal lining, produce acid to keep pH in intestine balanced.

3. Streptococcus thermophilus

They are used as starter culture for dairy foods other than yogurt like mozzarella cheese. It possess anti oxidant properties and protect intestine from mucositis during chemotherapy.

4. Yeast

Saccharomyces boulardii and Saccharomyces cerevisiae are involved in production of probiotics.

• TYPES OF PROBIOTICS:

1. NON VIABLE PROBIOTICS: These are dead.
2. FREEZE DRIED PROBIOTICS: These will die rapidly upon leaving refrigeration.
3. FERMENTATION PROBIOTICS: These are produced through fermentation.
4. VIABLE PROBIOTICS: These live with guaranteed shelf life and produce many health benefits.

• MODE OF ACTION OF PROBIOTICS:

1. Production of inhibitory compounds( example; Bacitracins and Polymyxins produced by Bacillus species).
2. Restore balance between good bacteria and bad bacteria.
3. Produce beta galactosidase to digest lactose.
4. Decreased production of carcinogenic metabolites.
5. Competition for adhesion sites and available energy sources.
6. Suppression of viable counts by production of hydrogen peroxide.
7. Secrete bactericidal proteins and decrease pH.
8. Alter host immune response by stimulation of IgA production and decreasing pro-inflammatory cytokines.

• ADVANTAGES: 

1. Treat high cholesterol.
2. Promote production of B group vitamins.
3. Used for treatment of lactose intolerance and Inflammatory Bowel Syndrome(IBS), Hepatitis diseases, antibiotic associated diarrhoea and other digestive upset.
4. Helps to stimulate peristaltic movement of gut to reduce constipation and greatly improve digestion.

• PROBIOTIC PRODUCTS:

1. Yogurt
2. Kefir
3. Kombucha
4. Miso(popular Japanese food)

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