In this presentation, I have briefly explained the application of Genetic Engineering in Dairy starter cultures and Dairy Farming.

1. Genetic Engineering in
the Dairy Industry

2. Genetic Engineering in
Starter - Culture

3. Introduction
● Dairy fermentations owe their historical origins to the
exploitation, from as long as 9,000 years ago, of the
random and accidental infection and souring of milk by
the then unrecognised lactic acid-producing bacteria.
● This process involves metabolic conversion of milk
sugar, lactose, into lactic acid.

4. ● Lactic acid bacteria used as starter cultures in
cheese production include Lactococcus lactis
subsp, lactis cremoris, and Leuconostoc
mesenteroides and Leuconostoc dextranicum.
● Starter cultures in yoghurt production include
Lactobacillus delbruekii sp. bulgaricus,
Lactobacillus helveticus and Streptococcus
thermophilus.

5. Cheese Production
● Starter cultures used by dairy fermentation
industry for cheese-making don't always
perform optimally but have potential to be
improved by genetic strategies .
● Variables that can be manipulated include
- Bacteria in starter culture
- Enzymes used in metabolic changes

6. ● Production of Lactic Acid
- The primary function of LAB is the production of
lactic acid from lactose which is done by a
plasmid DNA present in it.
- However, lac+ plasmid may be lost during
multiplication of starter culture so lactic
production is said to be unstable.
- Recently a nisin-producing starter culture that
produced acid at suitable rates for Cheddar
cheese manufacture has been developed.

7. - The starter culture was developed by combining
natural strain (lactose-fermenting, nisin-
producing) lactococus lactic sp. with lactose-
positive, nisin-producing transconjugant.

8. ● Proteolysis
- Caseins are the most significant substrates for
proteolysis in the preparation of fermented milks
and in cheese ripening.
- Increasing proteolytic activity and improving
starter cultures amino acid converting activity are
major aspects for cheese flavour improvement.

9. - Enzymes involved are proteinases
(endopeptidase and exopeptidase)
- To stabilize these enzyme genes, chromosomal
integration of target gene approach is used

10. ● Bacteriophage Resistance
- Bacterial infection during manufacture of
fermented milk products leads to significant
economic loss.
- Many phage - resistant plasmids are conjugative
and this factor is exploited to improve phage
resistance of phage-sensitive commercial
cultures.

11. ● Accelerated Cheese Ripening
- Traditional ripening of cheese takes upto 6-12
months depending on type of cheese under
controlled conditions.
- Enzymes synthesised from genetically modified
bacteria like proteinases, lipase and beta-D-
galatactosidade are used for enhancing the
ripening of cheese.

12. Genetic Engineering in
Dairy Farming

13. ● Changes In Milk Composition
- Chinese scientists injected transgenes into 300
dairy cows to change composition of the milk
produced similar to human breast milk as a
means of improving human neonatal nutrition.
- This is done by genetic engineering of bovine
mammary gland.

14. ● Increased Milk Production
- Somatotrophin(also known as Bovine
Somatotrophin BST) is a naturally occuring
hormone that controls milk production in cows.
- The ability of somatotrophin injections to
considerably increase milk production was
rapidly confirmed.
- Today, genetically modified bacteria (E.coli) are
used to produce the somatotrophin that is
administered to milk cows.

15. ● Milk for Lactose Intolerant Individuals
- Geneticists have introduced a gene which
causes lactose, the main sugar present in dairy
products, to break down into other sugars more
easily digestible by humans.
- To create a low-lactose milk producing cow,
scientists have injected a gene from
Archaebacteria into cow embryo cells using
cloning techniques.

16. 80%
of residents in USA and Africa are said to
be lactose intolerant.

17. ● Milk rich in Omega-3-fatty acids
- Normally found in fish oil and nuts, omega 3 fatty
acids protect against human heart disease and
plays a role in brain function.
- Genetically modified cow milk which has high
levels of Omega - 3 - fatty acids has been
produced.

18. - The milk contains 4 times as much Omega 3 fatty
acids than ordinary milk and half the amount of
Omega 6 unsaturated fatty acids which is linked
to cancer and heart diseases.
- Using cloning technology, a gene from
roundworm is transferred to cow embryos to
produce this milk.
- It is found that mammals do not naturally
produce Omega 3 fatty acids and neither can
they convert Omega 6 unsaturated fatty acid into
healthier forms.

19. Thanks!