industrial biotech

  • microbes are used as “biocatalyst” in large scale production of commercial products

  • use to carry out complex chemical transformations

  • can be used as

    • cells (yeast extracts)

    • biotransformation (steroid biotransformations)

    • products from cells (enzymes, antibiotics, food addictives, alcohol, chemicals)

enzymes

  • microbes are a good source of enzymes

  • they are secreted into culture medium to make purification easy

  • laundry detergents contains enzymes

    • proteases, lipases, amylases (for stain removal)

    • cellulase (fabric softening, brightening)

    • Bacillus licheniformis

  • microbes are good sources of enzymes

  • enzymes are secreted into culture medium making purification easy

  • syrup manufacturing

    • mostly applied for production of soft drink, bakery, confectionary

    • amylase - starch into glucose

    • glucose isomerase - glucose into fructose

    • fructose - monosaccharide widely used for food pharmaceutical and medical applications

    • isomerase - any one class of enzymes that catalyse reactions involving structural rearrangement of molecule

    • note: fructose twice sweeter and 10bil kg produced each year mainly for soft drinks, bakery, confectionary

agriculture

  • nitrogen is an essential component of nucleic acids and proteins but most organisms cannot use the nitrogen in the air

  • nitrogen fixation is a conversion of atm nitrogen to ammonia by lightning - some bacteria have enzymes to convert N2 to ammonium salt and nitrate which can be absorbed by plants

    • cyanobacteria spp.

    • azotobacteraceae spp.

    • rhizobium spp. (resides the nodule of legume fix N2)

    • frankia spp.

nitrogen fixing process
- conversion of atmospheric nitrogen to ammonium (NH4+) by nitrogen fixing bacteria (rhizobium)
- Nitrifying bacteria convert ammonium (NH4+) to nitrite (NO2-)
- Nitrifying bacteria convert nitrite to nitrate (NO3-)
- Nitrate taken up by plants

fermentation

  • absence of oxygen - microbes carry out fermentation to convert carbs such as sugar into an acid /alcohol in order to obtain energy (ATP)

  • microbial fermentation has been used for thousands of years to preserve food/improve taste, aroma, texture

  • Pyruvic acid

    • Propionibacterium

      • propionic acid, co2 → swiss cheese

    • Aspergillus, Lactobacillus, Streptococus

      • Lactic acid → cheddar cheese, yogurt, soysauce

    • Saccharomyces

      • co2, ethanol → wine, beer

    • Clostridium

      • Acetone, isopropanol → nail polish remover, rubbing alcohol

    • Escherichia, Acetobacter

      • Acetic acid → vinegar

yogurt

  • majority of fermented milk products rely on lactic acid bacteria belonging to the genera Lactobacillus, Lactococcus, Leuconostonc, and Streptococcus

    • gram pos that tolerates acidic conditions

    • non spore forming w strictly fermentative metabolism

  • lactic acid bacteria ferment lactose to produce lactic acids

  • lactic acids turn milk into curd

making yogurt at home

starting material - milk

substance in starting material to be fermented (nutrient for microbe) - lactose

chemical reaction involved - lactose → lactic acid

what chemical changes caused texture/taste of food to change from starting material → lactic acid bacteria from yogurt multiplies and fermented lactose into lactic acid that decreases the pH of the milk culture (sour taste), denaturing proteins found in milk

proteins change their texture to form curds (curdle texture)

beers and wines (alcoholic beverages)

  • fermentation carried our by yeast

  • wine: fermentation of fruits

    • fruits crushed and juice is mixed with yeast for primary fermentation (3-5 days) - to get sugar

    • secondary fermentation takes weeks to months in air tight barrels

    • wine then separated from sediments and stored at low temperature for ageing

    • sugar → ethanol + co2

    • microbe involved - Saccharomyce cerevisiae (yeast)

    • ethanol produced makes wine taste alcoholic

  • beer: fermentation of grains

    • germinating barley, wheat, etc. produces enzymes to convert starch into sugar

    • sugar → ethanol and co2

    • aqueous extracts which contains sugars and proteins are filtered and heat treated to distinct taste and colour

    • yeast added for fermentation

    • carbonated to become beer

    • microbe involved - Saccharomyce cerevisiae (yeast)

    • ethanol produced makes beer taste alcoholic,, carbonated comes from co2 dissolved in it

    • oxygen not needed to be present

    • if temp of mixture maintained at 50ºC

      • reaction would slow down as enzymes in yeast cells catalyse th reaction

      • high temp would denature enzymes thus decreasing/stopping enzymatic activities

  • distilled beverages: by concentrating alcohol from a fermentation by distillation e.g. vodka

  • sparkling wine: co2 is present, arising from a final fermentation by the yeast directly in the bottle e.g. champagne

  • vinegar - produced by acetic acid bacteria e.g. Gluconobacter and Acetobacter

    • starting material is wine/beer/apple cider

    • bacteria partially oxidises ethanol to acetic acid

    • nutrient in starting material for microbe - sugar

    • sugar → alcohol → vinegar

cheese

  • lactic acid bacteria (Lactococcus lactis) and rennin (enzyme) are added to milk

    • L. lactis converts lactose into lactic acids - curding

    • rennin converts casein to curds

  • what chemical changes caused the texture/taste of cheese to change from starting material

    • rennin (in cow stomach) - converts casein (milk protein) into curds

    • lactic acid curdles the milk

    • yeast and molds can be added to give cheese distinctive flavour and texture during ripening

  • liquid portion removed and curd allowed to ripen into cheese at controlled temp

  • yeast and molds can be added to give cheese its distinctive flavour and texture during ripening

  • Roquefort cheese crumpled for salad dressing - dark areas are results of extensive growth of molds

  • swiss cheese - holes formed by co2 released during the growth of Propionibacterium fermentation

probiotics

live microorganisms that are added to diets to provide health benefits beyond basic nutritive value

benefits

  • improve intestinal microbial balance and inhibit pathogens and toxin producing bacteria

  • prevent and treatment of pathogen-induced diarrhoea and urogenital infections

  • regulate immune response

  • anticancer effect

lactobacillus species

  • gram pos

  • rods

  • ferment lactose to lactic acids

  • observed benefits

    • kids fed with L. acidophilus are reported to have decreased incidence of paediatric diarrhea

    • L. acidophilus in intestine help to reduce stomach cramp and diarrhea in lactose intolerant subjects

    • prescribed for patient after antibiotic treatment to recolonise the gastrointestinal tact

    • enhances pathogen clearance, reduces inflammation etc

bifidobacterium lactis

  • gram pos

  • rods

  • club shaped/branched ends

  • strict anaerobic

  • added in milk powders/fermented milk products

  • improve lactose tolerance, produces bacteriocin to inhibit other intestinal bacteria etc