Sustainable agriculture is an agriculture practice which uses renewable practice which uses renewable resources, causes minimum pollution and maintain optimum yield level. Sustainability of agriculture will be enhanced if there is reduction in use of nonrenewable resources and decrease in level of pollution. The various component of sustainable agriculture are bio fertilizers, bio pesticides, developing resistant varieties and single cell protein. The nonuse of artificial fertilizers and chemical pesticides and use of bio pesticides as well as bio fertilizers in agriculture is called organic farming
IPM or integrated pest management is the practice of pest control through biological or natural methods and using the chemical pesticides to the minimum when it is essential. It consists of
(i) Sanitation: removal of crop residue and using it for maturing at a distance
(ii) Culture practices: Use of pest resistance varieties, crop rotation, mixed cropping and intercropping
(iii) Biological control: Allowing the natural predators, parasites and parasitoids of the pests to keep the population of the latter under check e.g. bugs and beetles
(iv) Natural pesticides: They are nonpollutant pesticides e.g. thurioside, azadirachtin, cinerin, pyrethrin
Microbes in industrial process alcoholic fermentation
• Louis Pasteur found for the first that beer and butter milk are produced due to activity of yeast and yeast like organism
• The nutrient medium is barley matt for beer, fermented rye malt for gin, fermented rice for sake, cashew apple for fenny, potato for vodka, fermented cereals for whisky, fermented molasses for rum and fermented juices for wines and brandy. Yeast does not possess sufficient diastase/amylase. Therefore, either 1% malt or Rhizopus is used when the nutrient medium consists complex carbohydrates as present in cereals and potato. Hydrolysis of starch is carried out in separate tank at high temperature (55OC) for 30 minutes. The crushed food mixed with hot water for obtaining malt is called mash. The sweetened nutrient medium prior to alcoholic fermentation is called wort
1. Bioreacter/fermentation tank is sterilized with the help of steam under pressure. The liquid nutrient medium or wort is added into the tank and sterilized similarly. It is then allowed to cool
2. When the liquid nutrient medium is cooled down to appropriate temperature, it is inoculated with appropriate strain of yeast. Fermentation occurs in three ways
(i) Batch process
Bioreactor is very large capacity up to 2,25,000 litre of medium. Yeast and nutrient are allowed to remain there till maximum alcohol content is achieved (6-12%). It is called wash. The same is removed and the tank sterilized for the next batch
(ii) Continuous process
There is regular removal of a portion of fermented liquor/wash addition of more nutrient
(iii) Feed batch process
It is intermediate between batch and continuous process. Here, the culture is continuously fed with fresh medium Immobilized yeast. Lately yeast is being used in immobilized state in calcium alginate beads. The technique is 20 times more efficient
3. In case of beer, the fermented liquor having alcohol content of 3-6% is filtered, lightly hopped and pasteurized. In case of wines, 10-27% alcohol content is achieved through refinement and concentration. Fortification by direct addition of alcohol may also be carried. Distillation is done in other cases. E.g. gin(41%), rum (40%), brandy (60-70%). Rectified spirit is 95% alcohol. Absolute alcohol is 100% alcohol
4. By products of alcoholic fermentation are CO2 and yeast. A number of other chemicals can be formed with the change of nutrient medium. pH and aeration -n propanol, butanol, amyl alcohol, pyruvic acid, succinic acid, lactic acid, caproic acid, caprylic acid, ethyl acetate, acetaldehyde, diacetyl, hydrogen sulphide etc
5. Beer: It contain 3-6% alcohol. Nutrient medium is barley grain which have been semi germinated and crushed to form malt. Before inoculation with yeast, the infusion of malt or wort is treated with hops (dried petals of vine Humulus lupulus) to provide flavor, colour and stability. Beer is allowed to age before pasteurization. Lager beer is prepared by carrying out ageing in the cold.
6. Wine: It is alcoholic beverage prepared from ripe fruits and fruit juices. Red wine is red due to colour from grape skin, Cider is apple wine. Alcohol content ranges from 10-20%. Sparkling wines are naturally carbonated due to continuation of fermentation after bottling. Champagne is the most popular sparkling wine other famous wines are port wines and sherry wines
7. Brandy : It has an alcoholic content of 60-70%. Brandy is prepared from distillation of generally grape wine but can also be mixture of distillates various fermented juices and wine
8. Whisky and other alcoholic drinks are prepared through distillation as the maximum content of alcohol in fermentation is 6-12%. Vodka has an alcoholic content 60-80%. Gin (40% alcohol) is flavored with juniper berries. Rum has 40% alcohol. The alcohol content of whisky varies with brand
Antibiotic synthesis by microorganisms
- Antibiotics are chemical substance produced by microorganism which can kill or inhibit the growth of disease causing microorganism. These also inhibit the metabolic activities of other microorganisms. The term ‘antibiotic was defined by Waksman in 1942. A microorganism which produces an antimicrobial substance is called an antibiont. At present more than 7000 antibiotic sunstances are known and approximately 100 are available for medical use
- The first antibiotic was penicillin, a product of the moulds Penicillium notatum and P.chrysogenum discovered by Fleming in 1928.
- Sir Alexander Fleming noticed a halo ( technically known as plaque or zone of inhibition) of bacterial growth around a contaminate blue-green mould on a staphylococcus plate culture. He concluded that the mould was releasing a substance that was inhibiting bacterial growth. He grew a pure culture of the mould and discovered that it was Penicillium notatum in 1928. P.chrysogenum is a strain was previously known as Penicillium notatum. P.chrysogenum has been used industrially to produce penicillin and nanthocillin X, to treat pulp mill waste and to produce the enzyme polyamine oxidase, phosphor gluconate dehydrogenase and glucose oxidase.
- Antibiotics are used (i) as medicine for treatment (ii) as preservatives in perishable fresh food articles (iii) As feed supplement especially poultry because they enhance growth
Microbes as nutritional supplements
- Yeast e.g. Saccharomyces cerevisiae, which is a deactivated test is known as nutritional supplement organisms. It is an excellent source of protein and vitamins, especially the B-complex. Vitamins required in metabolism. It is also required for minerals and cofactors essential for growth. Nutritional yeast is low in fat and sodium and fortified with vitamin B12
- It has a nutty cheesy flavor that makes it popular as an ingredient in cheese substitutes. It is also used as topping for popcorn and in mashed and fried potatoes, as well as in scrambled eggs. It is available in the form of flakes, as a yellow powder and is similar in texture to cornmeal. Chlorella (green algae) and Spirulina ( simple, one called organism) are also referred as source of protein
- Microbes are commercially used in various industries for the large scale production of various chemical substances such as organic acids, alcohol and enzyme. In the production of chemical substances, microbes are used for fermentation and oxidation reactions.
Solvents, acids, enzymes and Other bioactive chemicals
1. Solvents
Acetone, methyl alcohol and butanol are important industrial solvents. Which have been produced through fermentation of sugar and starch by Clostridium acetobutylicum and C.saccharoacetobutylcium. Glycerol is formed by adding sodium sulphite to alcoholic fermenter. It prevents ethanol formation. Instead glycerol is formed
2. Organic acids
(i) Acetic acid: it is both microbial and synthetic in origin, Vinegar is 10-13% ripened acetic acid. Initially molasses or other sugar solution is allowed to undergo alcoholic fermentation by yeast. It is an anaerobic process. As soon as 10-20% alcohol is formed, the liquid is filtered to remove yeast. It is aerated and inoculated with Acetobacter acetic. The latter produces acid.
When 10-30% acetic acid content is achieved, the liquid is filtered. The filtrate is allowed to ripen till the disagreeable smell disappears. It is pastured and called vinegar. The acid is concentrated and vinegar is used as souring agent, preservative and condiment. Acetic acid is used in plastics, pharmaceuticals, colouring agents, insecticides, production of solvents and flavoring agent.
(ii) Citric acid: Aspergillus niger, Mucor species can ferment sugar to produce citric acid. Citric acid is preservative and flavoring agent. It is also used in medicines, engraving, dyeing and inks
(iii) Lactic acid: First organic acid is to be fermented, lactic acid is obtained by activity of bacteria like streptococcus lacti, fungus Rhizopus etc. Over a variety of nutrient media like hydrolysed corn or potato starch, molassess, sulphates liquor etc. Lactic acid is used in cleansing, flavoring, preserving pickles, curing of meat. It is used as mordant in tanning, dyeing, printing of wool and preparation of plastics
(iv) Other organic preparations:
(a) Gallic acid is obtained with the help of Aspergillus niger. It is employed in ink making.
(b) Gluconic acid is manufactured through the agency of Penicillium purpurogenum, for use as calcium gluconate (providing calcium to infants, lactating mother and treating milk fever in high milk yield cows and in preparation of pharmaceuticals
(c) Butyric acid is formed by activity of Clostridium butyricum. It is the acid that occurs in rancid butter
3. Enzymes
(i) Pectinase: They are obtained from fungi grown on pectin containing media. Eg. Aspergillus niger, Pectinases are used in enhancing juice extraction from fruits, cleansing of fruit juice, removing bitterness retting of fibres and fermentation of green coffee
(ii) Proteases: They are obtained from both bacteria (e.g. Bacillus subtilis, B. lichenformis) and fungi ( e.g. Aspergillus oryzae). Proteases are used in enhancing tenderness of meat, extraction of fish liver oil, clarification and chill proofing of alcoholic drinks, synthesis of glue, cleaning of hides and in detergents for removing protein based strains
(iii) Lipase they are lipid digestive enzymes that are obtained by growing Candida lipolytica, Aspergillus niger etc lipases are used in flavouring cheese, hydrolyzing oils for soap manufacture and in detergent formulations for removing fat based stains
(iv) Amylases they are starch digesting enzymes which are obtained from Aspergillus oryzae, B. diastaticus etc. The enzymes are used in softening and sweetening of bread, desizing fibres, cleansing starch related stains, clearing starch related stains in utensils and clothes
(v) Streptokinase: It is also called tissue plasminogen activator or TPA which is obtained from haemolytic streptococcus species and modified genetically to be useful in human beings. It is used as clot buster or dissolving blood clots in vessels of patients having undergo mycocardinal infaction or heart attack
4. Cyclosporin A
It is an 11=membered cyclic oligo-peptide. It is obtained from fungus Trichoderma polysporum or Tolypocladium inflatum cyclosporin A has immunosuppressive property as it inhibits activation of T-cell response to transplanted organ
5. Statins
They are inhibitor of enzyme HmG can reductase of liver which forms mevalonate required for cholesterol synthesis. Statin are synthesised by activity of yeast Monascus purpureus
6. Vitamins
(i) Vitamin C: Acetobacter is helpful in dehydrogenation of D-sorbital and its conversion to L-sorbose. Which is precursor of vitamin –C or L-ascorbic acid
(ii) Vitmin B12 : Organism like Propionibacterium frendeureichii, Streptomyces oliaceus are used on nutrient medium made of starch, corn syrup or molasses. The cells are harvested and autolysed to separate the vitamin.