Chemical commodities from fungi..which include citric acid,itaconic acid,vitamins and fungal pigments.

1. CHEMICAL; COMMODITIES
FROM FUNGI
SUBMITTED BY- NIKITA PATHANIA
CENTRAL UNIVERSITY OF JAMMU
ROLL NO. 1641417
SEM. 7TH
SUBMITTED TO- Dr. RITIKA SHARMA

2.  COMMODITY :Something useful that can be turned to co
mmercial or other advantage.
 Several industrially important chemicals are
produced via biological processes using molds and
yeasts like:
 Citric Acid
 Itaconic Acid
 Vitamins
 Fungal Pigments
 In terms of world production volume, the most important
of these are citric acid.

3.  CITRIC ACID

4.  Citric Acid
 Citric acid is the principal organic acid found in citrus fruit. To meet with
increasing demands, it is produced from carbohydrate feedstock by
fermentation with the fungus Aspergillus niger and the yeast Candida. The
initial commercial Production of citric acid was achieved using A. niger in a
surface fermentation process.
 Citric acid’s main use is as an acidulant in soft drinks and confectionery.
 A number of fungi and yeasts have been used over the years for the
production of citric acid, but A. niger remains the preferred
fermentation organism for commercial production. The main
advantages of using this organism are its ease of handling, its ability to
ferment a wide variety of cheap raw materials, and high yields.
 A variety of raw materials such as molasses, starchy materials, and
hydrocarbons have been employed as substrate for the production of
citric acid.
 Molasses has been acclaimed as a low‐cost raw material and it contains
40–55% of sugars in the form of sucrose, glucose, and fructose.

5.  To ensure high productivity it is essential that the media contain major
nutrients such as carbon, nitrogen,and phosphorus, and also trace elements.
The fermentation process is also influenced by aeration, temperature and pH.
 The use of different carbon sources has been shown to have a marked effect on
yields of citric acid by A. niger. Aspergillus niger can rapidly take up simple
sugars such as glucose and fructose.
 The nitrogen sources for citric acid production by A. niger are generally
ammonium sulfate, ammonium nitrate, sodium nitrate, potassium nitrate, and
urea. The presence of phosphorus in the fermentation medium has a profound
effect on the production of citric acid. Too high a level of phosphorus promotes
more growth and less acid production. Potassium dihydrogen phosphate (0.1%)
has been reported to be the most suitable phosphorus source.
 a pH below 2 is required for optimal fermentation. Citric acid fermentation is
an aerobic process and increased aeration rates have resulted in enhanced
yields and reduced fermentation times.

6.  Aspergillus niger

7. Production of Citric Acid by
Filamentous Fungi
 Surface fermentation method
 Submerged fermentation method
 Solid-state fermentation method
1. Surface Fermentation
 Surface culturing was the first process employed for the large‐scale
production of microbial citric acid.
 They are simple to operate and install. Another advantage of this
culturing method is that energy costs for surface fermentation are
lower than those of submerged fermentation. The mycelium is grown
as a surface mat in shallow 50‐ to 100‐liter stainless‐steel or aluminum
trays. The trays are stacked in stable racks in an almost aseptic
fermentation chamber.

8.  Tray fermenter

9.  The carbohydrate source (usually molasses) for the fermentation
medium is diluted to 15% sugars, the pH is adjusted to 5–7. After the
addition of the nutrients the medium is sterilized, cooled, and pumped
into the trays. Inoculation is performed by introducing spores.
 Spores subsequently germinate and form a mycelial mat. The
temperature is maintained at 28–30 °C and the relative humidity
between 40 and 60%.
 Air provides oxygen to the organism and also controls the fermentation
temperature and the relative humidity. As the fermentation progresses
the pH decreases to below 2.0. If the fermentation pH rises to 3.0,
oxalic acid and gluconic acid may be formed in considerable amounts.
 Fermentation progresses for 8–12 days, after which time the
fermented liquid is poured out of the pans and separated
from the mycelium for further processing. Fermentation
yields are in the range of 70–75%.

11. 2. Submerged Fermentation
 Submerged fermentation is now more popular for the commercial production
of citric acid. It requires less space, is less labor intensive, and higher
production rates are obtained. With submerged fermentation a stirred tank
reactor or a tower fermenter may be used.
 In view of the low pH level that develops during fermentation and the fact that
citric acid is corrosive, the use of acid‐resistant bioreactors is desirable. An
important consideration with bioreactors designed for citric acid production is
the provision of an aeration system, which can maintain a high dissolved
oxygen level.
 The medium preparation in submerged fermentations involves appropriate
dilution of the carbon source, pre‐treatment addition of the appropriate
nutrients, and sterilization in line or in the bioreactor. Inoculation is
performed by the addition of either a suspension of spores or pre‐cultivated
mycelia.
 When spores are used they need to be dispersed in the medium, and therefore
addition of a surfactant is usually necessary. Under optimal conditions
fermentation is completed in 5–10 days.
 Submerged fermentation can be performed by continuous and fed batch
modes, but generally it is carried out by the batch feed mode.

15. 3. Solid‐State Fermentation
 The Koji process or solid‐state fermentation, developed in Japan,
is the simplest process for production of citric acid.
 This process is the solid‐state equivalent of surface fermentation.
 The raw materials used are sweet potato fibrous residues, rice or
wheat bran, and fruit wastes. The carbohydrate source is
moistened with water to about 70% moisture. The moist
carbohydrate is then steamed for sterilization, placed in trays,
and inoculated using conidia of A. niger. The pH at the start of
fermentation is 5.5. The starch is hydrolyzed by amylase
produced by the fungus and subsequently converted to citric
acid.
 The fermentation is complete in 4–5 days. The main problem
with this process is the presence of trace elements, which cannot
be removed by standard methods.

19.  Production of Citric Acid by Yeast
 Yeasts are also employed in the commercial production of citric acid
from various carbon sources. Yeast strains that are used in the
production of citric acid include Saccharomyces lipolytica, Candida
tropicalis, C. olephila, C. guillermondii, C. citroformans, and Hansenula
anomala.
 There are a number of advantages when using yeast in comparison with
Filamentous fungi:
 1.Yeasts can tolerate high initial sugar concentration; they are
insensitive to trace metals and can thus ferment crude carbon sources
without any treatment;
 2. they have a great potential for being used in continuous culture;
 3. they have a high fermentation rate. For commercial production of
citric acid by yeast, tower fermenters with efficient cooling systems are
employed.
 The pH is generally > 5.5, but can fall during fermentation.

20.  Candida tropicalis culture media

21.  Citric Acid Metabolic Pathways
 The exact mechanism for citric acid production is not clearly
understood but involves an incomplete version of the tricarboxylic acid
cycle.

22.  Citric Acid Recovery
 At present, most of the manufacturers use the classical
method of citric acid recovery which is a precipitation
technique using calcium salt followed by filtration and
subsequently treated with sulphuric acid.

23.  Itaconic Acid
 Itaconic acid is used to alter the dyeing characteristics of vinyl
polymers and also in the manufacture of polymers used in emulsion
paints.
 Itaconic acid accumulation was originally observed in Aspergillus
itaconicus and Aspergillus terreus, and mutants of this strain are now
more widely used.
 The main carbon sources used in the commercial production of
itaconic acid include glucose, together with inorganic salts, purified
molasses, or media containing a portion of beet molasses. Calcium and
zinc are also essential in the growth medium
 . The Fermentation Process
 Once the medium is prepared and sterilized, inoculation is performed
by the addition of either a suspension of spores or pre‐cultivated
mycelia.

24.  Fermentation temperatures for itaconic acid production are quite high at
approximately 40 °C. The pH of the media must be reduced to 2 to initiate
production; The fermentation is highly aerobic and continuous aeration is
required to decrease production losses.
 Following 72 hours of fermentation, yields of 60% can be obtained based on
the carbohydrate source supplied. Carbohydrate is metabolized, in Aspergillus
itaconicus cells, by glycolysis to pyruvate, which is further converted through
the citric acid cycle to aconitic acid. Aconitic acid is then converted to itaconic
acid by the enzyme aconitic acid decarboxylase, an enzyme that has been
reported to be extremely oxygen dependent.
 Itaconic Acid Recovery
 The mycelium is separated from the fermentation medium by filtration and the
resultant liquor clarified. The itaconic acid is then recovered by evaporation
and crystallization, ion exchange, or solvent extraction.

25.  Vitamins
 Vitamins, essential nutrients required in small quantities, have a
documented and accepted value to the health of humans and animals.
 There is a large need for extra vitamins, other than those derived from
plant and animal food sources, due to unbalanced food habits or
processing, food shortage, or disease. Added vitamins are prepared
either chemically or biotechnologically via fermentation or
bioconversion processes.
 microbiological processes for their production are rapidly emerging
and some are already taking over. Compounds such as riboflavin (B2),
ergosterol (provitamin D2), cyanocobalamin (B12), and vitamin C are
now produced exclusively via fermentation.

27.  Vitamin B2 (Riboflavin)
 Riboflavin is commonly used in animal feed and human nutrition. It is
produced by both synthetic and fermentation processes, with the latter
recently increasing in application.
 Although bacteria (Clostridium spp.) and yeasts (Candida spp.) are also
good producers, currently two closely related ascomycete fungi, Ashbya
gossypii and Eremothecium ashbyi, are considered the best riboflavin
producers. Ashbya gossypii is the preferred strain for production as E.
ashbyi is genetically unstable.
 Soya bean oil and soya bean meal are the substrates most commonly
used in A. gossypii fermentations.
 An alternative biotechnological process for the commercial production
of riboflavin is through the fermentation of yeast, that is, Candida
famata; mutants of this strain also exist which can produce up to 200 g
of riboflavin per liter following 8 days of fermentation.

28.  Vitamin D
 Vitamins D2 and D3 are used as antirachitic treatments and large
amounts of these vitamins are also used for fortification of food and
feed. Vitamin D2 (ergocalciferol) is obtained by the UV irradiation of
yeast ergosterol.
 Efficient fermentation processes for ergosterol accumulation have been
established. Of about 20 sterols encountered in S. cerevisiae,
ergosterol, zymosterol, and lanosterol are considered to be the major
sterols, of which ergosterol makes up over 90%.
 Yeast cells consume carbohydrate as energy and carbon sources by
aerobic and anaerobic metabolism. The whole process appears to be a
two‐phase process, with the ergosterol content increasing when the
specific growth rate is decreased.

29.  Fungal Pigments
 Many fungi produce pigments that have application in both the textile
and food industries. They could therefore be used for the direct
production of textile dyes or dye intermediates, replacing chemically
synthesized forms which have inherent environmental effects during
their production and waste disposal.
 Fungal pigments are known to exhibit unique structural and chemical
diversities and have an extraordinary range of colors.
 Carotenoids such as β‐carotene are produced by a wide range of
Mucorales fungi and are suitable for addition to a variety of foods. The
yeast Phaffia rhodozyma has become the most important microbial
source for the production of the carotenoid pigment astaxanthin and is
responsible for the orange‐pink color of salmonid flesh and the reddish
color of boiled crustacean shells.

30.  Polyketide pigments are produced in abundance by filamentous fungi, and
include quinones such as anthraquinones and naphthaquinones, dihydroxy
naphthalene melanin, and flavin compounds such as riboflavin. Yellow‐colored
anthraquinone pigments are produced by many fungi including Eurotium spp.,
Fusarium spp., Curvularia lunata, and Drechslera spp. Anthraquinone is an
important member of the quinone family and is a building block of many dyes.
 Emericella species have been shown to produce alternative yellow‐colored
pigments such as the epurpurins, falconensins, and falconensones.
 Monascus species produce orange water‐insoluble pigments such as
monascorubrin and rubropunctatin.
 These pigments are suitable as colorants for a broad variety of foodstuffs and
often serve as suitable replacements for the food dyes.

33.  REFERENCE:
 Fungi(Biology and Applications),Edited by Kevin
Kavanagh.
 Wikipedia.