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Biomedical subjects

P Nigam

Publications and source records attributed to P Nigam.

At least 37 records · Page 2Linked to original sources
PubMed2001

Racemic resolution of RS-baclofen using lipase from Candida cylindracea.

Baclofen is chemically (RS)-beta-(aminomethyl)-4-chlorobenzene propanoic acid. It is used in therapy of pain and as a muscle relaxant. Baclofen produces analgesia by increasing the concentration of gamma amino butyric acid (GABA), the major rapid inhibitory transmitter. Both the isomers of baclofen have different therapeutic activity with respect to their interaction to the receptors at the site of action. Lipase from Candida cylindracea has been used as a catalyst for resolving racemic mixtures of numerous drug molecules. The present investigation deals with the racemic resolution of RS-baclofen using lipase from Candida cylindracea and a study of the factors affecting resolution.

Baclofen↗
PubMed2000

Biotechnological potential of coffee pulp and coffee husk for bioprocesses.

Advances in industrial biotechnology offer potential opportunities for economic utilization of agro-industrial residues such as coffee pulp and coffee husk. Coffee pulp or husk is a fibrous mucilagenous material (sub-product) obtained during the processing of coffee cherries by wet or dry process, respectively. Coffee pulp/husk contains some amount of caffeine and tannins, which makes it toxic in nature, resulting the disposal problem. However, it is rich in organic nature, which makes it an ideal substrate for microbial processes for the production of value-added products. Several solutions and alternative uses of the coffee pulp and husk have been attempted. These include as fertilizers, livestock feed, compost, etc. However, these applications utilize only a fraction of available quantity and are not technically very efficient. Attempts have been made to detoxify it for improved application as feed, and to produce several products such as enzymes, organic acids, flavour and aroma compounds, and mushrooms, etc. from coffee pulp/husk. Solid state fermentation has been mostly employed for bioconversion processes. Factorial design experiments offer useful information for the process optimization. This paper reviews the developments on processes and products developed for the value-addition of coffee pulp/husk through the biotechnological means.

Journal Article↗
PubMed2000

Isolation of thermotolerant ethanologenic yeasts and use of selected strains in industrial scale fermentation in an Egyptian distillery.

An enrichment and isolation program for new ethanol-producing thermotolerant yeasts as well as a screening program of some known thermotolerant strains resulted in the selection of several strains capable of growth at 40-43 degrees C. Among these strains four grew and fermented sugar cane molasses at 43 degrees C under batch conditions with sugar-conversion efficiencies >94% and ethanol concentrations 6.8-8.0% (w/v). The two best-performing strains, a Saccharomyces cerevisiae F111 and a Kluyveromyces marxianus WR12 were used in eight 87.5 m(3) fermentation runs (four using each strain) for industrial ethanol production in an Egyptian distillery using sugar cane molasses. Mean ethanol production was 7.7% and 7.4% (w/v), respectively, with an added advantage of cooling elimination during fermentation and higher ethanol yields compared to the distillery's S. cerevisiae SIIC (ATCC 24855) strain in use. The isolate S. cerevisiae F111 was subsequently adopted by the distillery for regular production with significant economical gains and water conservation.

Biotechnology↗
PubMed2000

Decolorization of Remazol Black-B using a thermotolerant yeast, Kluyveromyces marxianus IMB3.

The ability of Kluyveromyces marxianus IMB3 to decolorize Remazol Black-B dye was investigated. The effect of environmental conditions, such as pH and temperature were examined. No noticeable effects on decolorization were observed when pH varied from 3.0-5.5. Maximum colour removal, 98%, was achieved at 37 degrees C. Little or no colour removal was detected when K. marxianus IMB3 was incubated under anaerobic conditions. Further investigation, in which decolorization was monitored under extreme temperatures and low pH (to inhibit growth) and using ten fold dense inoculum, revealed that decolorization was due to biosorption to the yeast cells and not due to a metabolic reaction.

Biomass↗
PubMed2000

Advances in microbial amylases.

This review makes a comprehensive survey of microbial amylases, i.e. alpha-amylase, beta-amylase and glucoamylase. Amylases are among the most important enzymes and are of great significance in present-day biotechnology. Although they can be derived from several sources, such as plants, animals and micro-organisms, the enzymes from microbial sources generally meet industrial demands. Microbial amylases could be potentially useful in the pharmaceutical and fine-chemical industries if enzymes with suitable properties could be prepared. With the advent of new frontiers in biotechnology, the spectrum of amylase application has widened in many other fields, such as clinical, medicinal and analytical chemistries, as well as their widespread application in starch saccharification and in the textile, food, brewing and distilling industries. In this review, after a brief description of the sources of amylases, we discuss the molecular biology of amylases, describing structures, cloning, sequences, and protoplast fusion and mutagenesis. This is followed by sections on their production and finally the properties of various amylases.

Amylases↗
PubMed1999

The realm of microbial lipases in biotechnology.

In this review, a comprehensive and illustrious survey is made of the applied aspects of microbial lipases in modern biotechnological practices. Lipases are the most versatile biocatalyst and bring about a range of bioconversion reactions such as hydrolysis, interesterification, esterification, alcoholysis, acidolysis and aminolysis. After a brief description of the microbial sources of lipases, the pivotal role of lipases in the processes and products of the food and flavourings industry is illustrated. An illustration is presented of biomedical applications. The panorama of lipases in the manufacture of fine chemicals is depicted with special emphasis on pharmaceuticals, pesticides, cosmetics, biosensors and detergents. Widening applications such as those in waste management and improved tanning techniques are other novel aspects of lipase utilization that are discussed in this review.

Bacteria↗
PubMed1998

Continuous ethanol production from sugarcane molasses using a column reactor of immobilized Saccharomyces cerevisiae HAU-1.

A fermentation system for the continuous ethanol production from sucrose and molasses using calcium alginate immobilized Saccharomyces cerevisiae strain HAU-1 has been optimised. Immobilization of active yeast cells (30%, w/v) was accomplished in 1.5% calcium alginate and these yeast-beads were employed for ethanol production in a vertical column reactor. High ethanol productivity was achieved with a medium containing 10%, w/v sucrose at a dilution rate of 0.20 h-1. Alginate beads containing 30-50% yeast cell--mass resulted in high productivity 60.4 g l-1 h-1). Sugarcane molasses containing 15% total sugars was fermented in column reactor to produce 6.0%, v/v ethanol in continuous system. These yields could be improved to 7.0% with overall 11% increase in fermentation--efficiency with the use of acid-clarified sugar cane molasses medium.

Alginates↗
PubMed1996

Process optimization for continuous ethanol fermentation by alginate-immobilized cells of Saccharomyces cerevisiae HAU-1.

Continuous ethanol production by immobilized cells of Saccharomyces cerevisiae HAU-1 has been studied using synthetic and molasses based medium in column reactors. Immobilization of 30% yeast cells biomass (wet) in 1.5% calcium alginate gel resulted in the production of 20.8 g. l-1.h-1 alcohol at a dilution rate of 0.36 h-1 with approximately 1/3rd volume of the column reactor packed with gel beads. Optimum diameter of the beads was found to be 3.5 mm for efficient fermentation. The size of the column reactor (length to diameter ratio) also affected the productivity and fermentation efficiency due to gas hold-up and mass transfer effects. Molasses could also be fermented by this system but at a lower fermentation efficiency which could be improved, to some extent, by supplementation with nutrients.

Alginates↗
PubMed1995

Simultaneous raw starch hydrolysis and ethanol fermentation by glucoamylase from Rhizoctonia solani and Saccharomyces cerevisiae.

Crude glucoamylase preparation from Rhizoctonia solani was used to saccharify raw and cooked starch. Various concentrations of potato starch and wheat flour from 10-40%, w/v were used for mashing but 30% was found to be the optimal and economical. The saccharified mash yielded 5.89%, v/v ethanol in a simultaneous saccharification and fermentation process using a yeast strain Saccharomyces cerevisiae (SC-39) at 35 degrees C for 4 days. Removal of inhibitory substances from the fermenting broth through dialysis caused considerable increase in ethanol production.

Ethanol↗
PubMed1995

Biological treatment of distillery waste for pollution-remediation.

The biological treatment of spent wash from molasses distilleries was investigated. Analysis of raw spent wash showed it to be a recalcitrant waste, with a high COD of 85,170 mg/l and containing inhibitory phenolic compounds. Reverse phase thin layer chromatography identified gallic and vanillic acid present in spent wash. The fungi Geotrichum candidum, Coriolus versicolor, Phanerochaete chrysosporium and Mycelia sterilia were screened for their ability to decolourize spent wash and to reduce the COD level. A 10 day pretreatment with Geotrichum candidum at 30 degrees C resulted in reducing the COD by 53.17% and total phenols by 47.82%, enabling other bioremediating organisms to grow. Coriolus versicolor immobilized in a packed-bed reactor reduced the COD of spent wash by a further 50.3%, giving an overall reduction in COD of 77% to 15,780 mg/l. A small amount of decolourization was achieved (4.2%), although the spent wash was still coloured. Present studies are encouraging and indicate that it is possible to bioremediate spent wash using a multi-stage treatment process involving an initial pretreatment step with Geotrichum candidum.

Bacteria↗
PubMed1994

Production, partial characterization, and potential diagnostic use of salicylate hydroxylase from Pseudomonas putida UUC-1.

An unusual strain of Pseudomonas putida UUC-1 capable of growth at high salicylate concentration (10 gl-1) was investigated with the aim of developing an assay and a biosensor system for determining salicylate in body fluids by utilizing the salicylate hydroxylase enzyme. Medium and growth condition optimization were carried out under chemostat conditions. The highest biomass yield was at 4.0 gl-1 salicylate, 25 degrees C, pH 6.5, and 0.2 h-1 dilution rate. Growth occurred at up to 0.45 h-1 dilution rate, producing 236 Ul-1 enzyme activity and an output of 424 U h-1. The activity and productivity were higher than any reported in the literature for this enzyme. It had a Km value of 2.07 +/- 0.32 microM and an M(r) of approximately 43,000. In addition, its specific activity in the crude extract (0.8-0.9 U mg-1 protein) was similar to the commercially available enzyme. No plasmid DNA was detected in this strain, and no salicylate-negative isolates were obtained when curing with mitomycin C. It is therefore proposed that our strain has a chromosomally located inducible salicylate hydroxylase gene that enables it to grow at high salicylate. This strain also offers a means of cheaply producing large quantities of the enzyme through standard fermentation techniques.

Biosensing Techniques↗
PubMed1993

Production of the enzyme dihydrofolate reductase by methotrexate-resistant bacteria isolated from soil.

Six bacterial cultures isolated from soil were capable of growing in the presence of methotrexate (MTX). Two strains, PFR-1 and 3, developed resistance to 500 micrograms cm-3 MTX in the medium and produced elevated levels of the enzyme dihydrofolate reductase (EC 1.5.1.3): 2580 and 2702 U dm-3 compared to the sensitive parent strains (28 and 35 U dm-3). Isolate PFR-3 showed maximum enzyme production (4950 U dm-3, specific activity 12.56 U mg-1 in flasks and 5737 U dm-3, specific activity 14.80 U mg-1 in 5-dm3 fermenter) during exponential phase of growth (6 h) at 37 degrees C and pH 7.0.

Chromatography, High Pressure Liquid↗
PubMed1993

Dihydrofolate reductase synthesis in continuous culture using a methotrexate-resistant Escherichia coli.

A methotrexate-resistant strain of Escherichia coli Type I produced exceptionally high levels of the enzyme dihydrofolate reductase (EC 1.5.1.3) in 6 h of batch fermentation. The culture had markedly improved performance under chemostat culture conditions in terms of enzyme yield and output. Temperature, pH, dilution rates, and nutrient composition were optimized under chemostat culture conditions. A maximum enzyme yield of 10,360 U l-1 and a specific activity of 22.84 U mg-1 were obtained under chemostat conditions at pH 7.0, temperature 37 degrees C, and dilution rate 0.2 h-1, using media containing 1.0 and 0.6% (w/v) dextrose and yeast extract, respectively. The culture's performance and enzyme yields in chemostat and the feasibility of large-scale production are discussed.

Bacteriological Techniques↗
PubMed1993

Clinico-therapeutic profile of pyogenic liver abscess.

Nineteen consecutive patients of pyogenic liver abscess (13 males, 6 females, mean age 45.2 +/- 6, 5 years) were studied over a period of 5 years for the clinical profile and therapeutic efficacy of percutaneous aspiration. Majority of them presented with spiking fever (94.7%), pain over right upper quadrant of abdomen (53.8%) and often with prostration and shock (31.6%). The onset has been rather acute in patients with multiple abscesses (7 cases). Ascites (10.5%), clubbing of fingers (15.8%) and splenomegaly (10.5%) were observed in cases with long duration of illness. There has been the polymorphonuclear leucocytosis (89.5%) and mild to moderate anaemia (52.6%). Jaundice (42.1%) was usually mild degree (serum bilirubin 4.6 +/- 2.4 mg/dl). The serum transaminases and alkaline phosphatase were raised in 94.9% of cases. Ultrasonography revealed predominantly hypoechoic (54.1%) areas with frequent distal acoustic enhancement and internal echoes (21.6%). Seven patients had multiple abscesses with 25 lesions (size 5.2 +/- 4.6 cms) situated mainly over antero-inferior segment of the right lobe (45.9%) of the liver. The blood and pus cultures demonstrated the micro-organisms (positive in 63.9% and 86.6% respectively) predominantly of bowel flora including facultative gram negative rods and anaerobes. Mortality was 26.5% and pleuro-pulmonary complications were the commonest (26.4%) one. 15 cases were treated by percutaneous aspiration, proper antibiotic and metronidazole with encouraging results (only two deaths). Complete resolution of abscess took place in 14.2 +/- 1.2 weeks (range 6 weeks to 7.5 months). It is emphasized that percutaneous needle aspiration is useful both for diagnosis and treatment of pyogenic liver abscess.

Adolescent↗