This blog is a little effort to make biotechnology concepts simplified to all the students in the degree classes from all the universities.I took the initiative to make concise and well formulated notes supported with the diagrams.I have struggled a lot in making notes and searching for the concepts by digging library books and surfing various sites. All i want is to create one place where you can look up to biotechnology notes and rely upon them as i have put up a lot of effort on them.
belong to a group of proteolytic enzymes. They are obtained by microbial
fermentations and are meant to use in leather industry for Dehairing, bating
and soaking purposes. Their major use
is in detergent industry too where they are used for breaking proteinaceous
matter caused by body secretions, food stuffs and blood stains. These enzymes
are obtained from plants, animals and microbial sources. Animal and Microbial
Proteases from Fungi and bacteria re used in the pretanning processes of
Proteases are mixture of Trypsin, Chymotrypsin and various Peptidases which may
contain amylase or lipase as secondary enzymes.
differ in their pH range as follows:
Proteases: pH 2.5 – 6.0
derived from A. satoi
Proteases: belong to group of serine proteases. More heat sensitive
deactivate at 600
Proteases: Obtained from Aspergillus and Penicillium
involves the digestion of basal cells of hair bulb and cells of malphigian
layer. This is followed by loosening of hair with an attack on outermost sheath
and breakdown of inner root sheath and parts of hair that are not keratinized.
Enzymes used in dehairing process are:
been developed especially for dehairing of skins and hides. It is an alkaline
protease derived from A. Flavus. It
grows rapidly on wheat bran and produce large amount of protease.
bacteria have gained much importance because of commercial interest , easy
production, high yield and easy recovery of enzyme. Examples are, Bacillus and Streptomyces spp.
hydrolyse Keratins are obtained from S.
is the first operation where in hides and skins are cleaned and softened with
water. Soaking is necessary for solubilisation and elimination of salts and
globulin proteins contained within fibrous structures of hides and skins. It is
carried out at alkaline conditions at temperature of 10-200C.
of soaking are production of leather with less wrinkled skin.
Alkaline Proteases of Bacterial & Fungal origin has been used for soaking which
reduces the need of chemicals.
Bating is a process in which
hides are softened by treating them in warm infusion of animal dung and product
used for such purposes is called as BATE. Main objective of bating is to remove
proteinaceous materials like albumin, globulins, mucoids from hides and skin
and allow splitting up of collagen fibres to facilitate penetration of tanning
materials and other chemicals, thereby giving finished leather with desired
properties like feel, softness and pliability etc. Principal materials which a
bate contains are proteolytic enzyme, a carrier for enzyme, wood flour and
deliming agent like Ammonium chloride.
Enzymes from Aspergillus spp. are used in bating.
A combination of both mold
and pancreatic enzymes are ideal bates.
Degreasing is an essential
step for production of glove and clothing leather. This process involves
removal of excess natural fats from greasy skin. This grease results in defects
like uneven dyeing, finishing and staining. Degreasing helps to obtain soft and
pliable;e leather for garment manufacture.
It is carried out using
aqueous emulsification with detergents or by solvent extraction since solvents
are hazardous. So Lipase is used as an alternative for various solvents.
Lipase from Rhizopus has been
very effective in degreasing of sheep skins.
Lipase from A. Niger is also a
good degreasing agent.
Bacterial Lipase at pH of 9-9.4 is good for degreasing pig
term is referred to all enzymes which cleave beta, 1-4 glycosidic linkages in
cellulose. Many bacteria and fungi are celluloytic but preparations marketed
for industrial applications are derived from Aspegillus niger, Neurospora
and Trichoderma viridae. Aspergillus
enzyme exerts good activity on CMC (carboxy methyl cellulose) but fails to
attack on solid cellulose because it lacks a important component i.e. C1
Cellulase. Cellulase is multienzyme complex with 2 important components called C1
and Cx. Both have important functions.
attack upon native cellulose of higher crystallinity while Cx cannot
attack such kind of cellulose but can split in turn the cellulose fragments
which have been derived by action of C1.
produces an enzyme complex with high levels of C1 cellulase which
extensively degrades insoluble cellulose.
Cultivation & Purification
scale fermentation A. niger is mostly
cultured by wheat bran tray method. This process yields high levels of enzyme. Extraction
of cellulose from solid substrate cultures is performed by percolation of dried
mold bran with 0.02 to 0.1 M lactic acid.
Neurospora and Trichoderma are grown by submerged
culture. For continuous culture it is advantageous that T. Viride produces a suspension of short mycelia threads, rarely
forming pellets. For submerged cultivations bran and wheat straw pre-treated
with alkali can be used as a source of
cellulose. Ammonium ions can be used a suitable nitrogen source. A correct pH
profile is necessary to give optimum enzyme yields in batch culture
concentration and purification of enzyme is carried out by precipitation,
adsorption and gel filtration techniques.
sulphate is used for precipitation followed by centrifugation at 10,000 g for
10 minutes. After separating the sediment supernatant is subjected to re centrifugation
for 10,000 g for 10 minutes. Precipitates are suspended in 0.5 M acetate buffer
with pH 5 and crystallisation procedures are followed.
ØCellulase is currently used to improve texture and palatability of poor
ØIt also accelerates drying of vegetables.
ØA potential use of cellulose is conversion of cellulosic material
to glucose and other sugars which in turn can be used as microbial substrates
in variety of fermentations e.g. Alcohol.