Beta carotene is an important carotenoid used as a natural colorant and precursor to vitamin A. It has antioxidant properties and potential health benefits. Beta carotene can be produced through biotechnological processes using microorganisms like fungi, yeast, bacteria, and algae. These production methods offer benefits over extraction from plants like lower costs and replacing synthetic colorants. Key factors that influence microbial beta carotene production include carbon source, temperature, aeration, metal ions, and light exposure. Downstream processing after fermentation is also important to recover intracellular beta carotene.

1. Beta Carotenoids
BY MOHIT KOHLI

2. • Carotenoids are used as natural colorant (red and yellow)
• Beta carotene are most important economical carotenoid
• Precursors of vitamin A
• Bioative phytochemicals [reduce risk of cancer, cardiovascular diseases etc.]
• Lipid soluble and also can be added to hydrophilic matrices (juice as provitamins)
• Finds application in food industries, poultry and aquaculture
•They are terpenoid pigments of 40 carbon atoms derived biosynthetically from
geranyl- geranyl pyrophosphate
• Shows antioxidant properties in cyclic form
Geranyl-geranyl pyrophosphate

3. a. Beta-carotene, b: Torulene/ xanthophylls c. Astaxanthines d. Canthaxanthin
a and b have carbon and hydrogen backbone and c and d have oxygen

4. Industrial process can be carried out by:
i) Biotechnological processes using filamentous fungi, yeasts, bacteria or microalgae
ii) Solid-liquid extraction from plants.
Benefits of microbial production:
• Use of low cost substrate
• Cost effective process
• Microbial carotenoids can replace synthetic colourants
Microbes: [bacteria, yeast, fungi, algae]
• Blakeslea trispora
• Phycomyces blakesleeanus
• Rhodotorula spp
• Xanthophyllomyces dendrorhous
• Corynebacterium michiganense, Micrococcus roseus, Brevibacterium spp.,
Bradyrhizobium spp., Gordonia jacobaea and Dietzia natronolimnaea
• Microalgae: Chlorella, Dunaliella, and Haematococcus

5. Producers of beta carotenoids
Bacteria
• Rhodotorula glutinis,
• Rhodotorula minuta,
• Rhodotorula mucilaginosa,
• Rhodotorula acheniorum
• Rhodotorula graminis
Yeast
• Sporobolomyces roseus,
• Sporobolomyces salmonicolor
• Sporobolomyces patagonicus

6. General pathway of Carotenoid production production by yeast
acetyl CoA
3-hidroxy-3-methyl glutaryl-CoA (HMG-CoA)
Mevalonic acid [first precursor for terpenoid biosynthesis]
Isopentenyl pyrophosphate
Isomerized
Dimethyl allyl pyrophosphate [DMAPP]
Prenyl transferase
Geranyl-geranyl pyrophosphate [GGPP]
Phosphorylated by MVA
Kinase and then
decarboxylated

7. Condensation of
two molecules of GGPP
Phytoene
(First C40 carotene of the pathway)
Desaturated to form lycopene
[β -carotene, γ -carotene, Torulene, Torularhodin
and Astaxanthin]

8. Factors influencing production of beta-carotene in yeast [carotenogenesis]
• Carbon source [whether the sugar is fermentable or non-fermentable which determines
its if ethanol will be produced or succinate will be converted to acetyl co-A]
• Light : Microbes needs to protect themselves from light which may cause damage,
carotenogenesis is photo-protective method. Production is affected positively by white
light.
[There have been report of higher carotene production using UV rays by some UV
resistance strain and also use of LED lights for enhancing production of carotenes]
• Temperature [regulates enzyme concentration involved in carotenoid production]
• Aeration: Carotenogenesis is an aerobic process [air flow rate is essential factor for
substrate assimilation, cell growth. Decreased aeration may lead to production of
cartenoids other than beta-carotene]
• Metal ions and salts (Ba, Fe, Mg, Ca, Zn and Co) have also been demonstrated to be
stimulants carotenoids production
• Solvents and natural agents: Ethanol etc.

9. Substrates:
1. Grape juice
2. peat extract
3. peat hydrolyzate
4. hydrolyzed mustard waste
5. hydrolyzates of eucalyptus globules wood
6. hydrolyzed mung bean waste flour
7. sugar cane juice
8. sugar cane and sugar-beet molasses
9. corn syrup
10. Corn hydrolyzate
11. milk whey
Medium composition
sample contained total solid 11% mainly; lactose 4.6%, protein 0.7%, fat 0.11% and
ash 0.09%. Minerals were 1.3 mg, 4.8 Na, 0.8 K, 0.3 Fe and 0.08 Zn ppm

10. The microbial production of carotenoids involved several steps:
i) Selection of the appropriate substrate. The raw materials utilized might or not be
pretreated depending on the fermentative capacity of the microorganism and the type
of enzymes produced.
ii) Bioreactor. The bioreactor configuration and operational variables are crucial for the
maximum yields of the process.
iii) Downstream processing. Production of intracellular pigments is limited by the
complexity of “downstream” processing. Cell disruption is a critical step to recover
intracellular compounds and it affects recovery yield and carotenoids properties

12. Downstream processing:
• Analysis of product
• Separation of components by chromatography
• Determination of biotic components