the chymosin content of the rennin causes a specific and rapid cleaveage of the kappa-casein component of the casein micelles. This protein stabilises the micelles and after cleavage, the casein proteins precipitate under the influence of the calcium ions. Chymosin specifically recognises the sequence from His 98 to Lys 111 and cleaves the peptide bond between Phe 105 and Met 106 in the kappa-casein chain:
http://www.ncbi.nlm.nih.gov/pubmed/22281325Current strain improvement strategies have already contributed to creating more efficient and safer enzyme production strains. This trend will undoubtedly continue as the knowledge about the genetic make-up of microorganisms used for enzyme production expands and new genetic techniques emerge.
Recombinant dna technology for food uses
Recombinant enzymes for food processing Uzair Shah Hashmi
Food-processing enzymes from recombinant microorganisms•food processing and in the production of food ingredientsEnzymes traditionally isolated from culturable microorganisms, plants, and mammaliantissues are often not well-adapted to the conditions used in modern food productionmethods recombinant DNA technology steps inmanufacture novel enzymes suitable for specific food-processing conditions. How ?• by screening microorganisms sampled from diverse environments•by modification of known enzymes using modern methods ofprotein engineering AdvantagesImprovement of microbial production strains• increase enzyme yield by deleting native genes encoding extracellular proteases• fungal production strains have been modified to reduce or eliminate their potential for production of toxic secondary metabolites
Improved pectinase production in Penicillium griseoroseum recombinant strains.Experiments have done to obtain a recombinant organism that will be having the ability toobtain pectin lyase (PL) and polygalacturonase (PG) and for that penicillium griseoroseum thatproduced both PL &PG simultaneously.•Firstly a strain that was reported to produce high concentration of PL was taken.•It was then transformed using pAN52pgg2 plasmid which was having a foreign gene of PG of P.grieoroseum and it was having a promoter from Aspergillus nidulans•The newly transformed P. grieoroseum T20 when checked was producing higher concentrationsof both PG and PL, around 143 folds higher PL, and 15 folds greater PG.•This recombinant strain uses carbon sources of low costs that is very economical•The enzyme preparation commercially available is free of cellulolytic and proteolytic activities.•This is an efficient system that uses P. griseoroseum to express and secrete proteins.
Also known as renninsingle polypeptide chain of 323 amino acids•2 types differ only by one amino acidChymosin A (aspartic acid residue at position 286)Chymosin B (glycine residue at position 286 )‡•Main coagulating enzyme found in rennet which is used extensively in cheese production.•hydrolyses a specific site in kappa-casein of milk•kappa-casein acts as micelle stabilizer•‡Precipitation of insoluble constituents
Search for an alternative rennet•increasing demand•shortage of calf stomachs•ethical issues with animal slaughteringKluyveromyces lactisincrease Chymosin production has been made through expression of calf Chymosingene in recombinant K. lactis Advantages of K. Lactis•Non toxicogenic GRAS microorganism approved by US FDA•‡Unlike p. Pastoris it does not require methanol to induce proteinsecretion•‡Unlike E. coli it doesnt secrete the expressed protein enclosed ininclusion bodies
comparative study of 4 different recombinant chymosins•Recombinant bovine Chymosin is the most frequently usedChymosin in the industry•new sources of recombinant Chymosin, such as goat, camel, orbuffalo, are now available.When compared with other 3 enzymes•Recombinant goat Chymosin exhibited the best catalytic efficiency•recombinant goat Chymosin exhibited the best specific proteolyticactivity,•recombinant goat Chymosin exhibited a wider pH range of action,•recombinant goat Chymosin exhibited a lower glycosylation degree