In this study hyper-production of citric acid Aspergillus niger was carried out using agro-industrial residues as carrier substrates in solid state fermentation (SSF) of sucrose molasses medium. It was concluded from this study that banana stalk was a good carrier substrate among the six substrates (Corncobs, corn stover, wheat straw, wheat bran and sugarcane bagasse) used for citric acid production in SSF of molasses medium and SSF gave higher citric acid production as compared to liquid state fermentation (LSF). Mutants of Aspergillus niger were produced through UV irradiations, Ethyle methane sulfonate (EMS) and Ethidium bromide (EB) for different time periods and Among the different mutants selected using selective marker, EB treated mutant Aspergillus niger EB-3 (treated for 90 minutes) was the best mutant for enhanced production of citric acid. Moreover, citric acid production by the mutant could be substantially enhanced to 112 mg/mL by careful optimization of the SSF parameters and by the addition of different metabolic inhibitors and metal ion complexing compounds.

Isolation of active ingredients from medicinal plants and characterization can be traced to the beginning of 19th century. Large number of drugs from medicinal plants were discovered and introduced in modern pharmacopoeias during 1850-1950. In the present study, Leaves of 7 species of different medicinal plants named Hygrophila auriculata (Talmakhana) Abru precatorius (Kaincha), Morinaga olifera (Sohanjna), Withania sominifera (Ashwaganda), Cartoon tiglium (Jamal ghota), Solanum nigram (Peelo) and Psoralae corylfolia (Babachi) were put on extraction using extraction buffer. Protein contents of all extracts were determined using bovine serum albumin (BSA) as standard Biuret method. All extracts were purified by ammonium sulphate precipitation and gel filteration chromatography using sephadex G-200 gel. Antibacterial activity of all these extracts before and after ammonium sulphate precipitation and gel filteration fraction having maximum protein contents was assayed.

Aldose 1-epimerase or mutarotase is the enzyme that responsible for carbohydrate metabolism and converts the alpha anomer into beta anomer of glucose. This enzyme was extracted from bovine kidney cortex. Crude enzyme exhibited the activity of 14.92 U mL-1 with specific activity of 0.153 U mg-1 proteins. The enzyme activity and specific activity was increased to 53.75 UmL-1 4.981 Umg-1 respectively after 38-60% ammonium sulfate precipitation and it was further increased to 73.27 UmL-1 and 11.67 Umg-1 when subjected to diethylaminoethyl (DEAE) cellulose chromatography. Further purification was carried out by passing it through Sephadex G-150 column and observed increase in activity 79.26 UmL-1 with 19.55 Umg-1 specific activity. The optimum pH and temperature were recorded as 8.5 and 37 oC respectively. Different stabilizers (glycerol, sodium benzoate, sodium citrate) were used to study their effect on stability of enzyme.