Biomedical subjects

P Nigam

Publications and source records attributed to P Nigam.

At least 19 recordsLinked to original sources

PubMed2006

Evaluation of freeze-dried kefir coculture as starter in feta-type cheese production.

The use of freeze-dried kefir coculture as a starter in the production of feta-type cheese was investigated. Maturation of the produced cheese at 4 degrees C was monitored for up to 70 days, and the effects of the starter culture, the salting method, and the ripening process on quality characteristics were studied. The use of kefir coculture as a starter led to increased lactic acid concentrations and decreased pH values in the final product associated with significantly higher conversion rates compared to salted rennet cheese. Determination of bacterial diversity at the end of the ripening process in salted kefir and rennet cheeses by denaturing gradient gel electrophoresis technology, based on both DNA and RNA analyses, suggested a potential species-specific inhibition of members of the genera Staphylococcus and Psychrobacter by kefir coculture. The main active microbial associations in salted kefir cheese appeared to be members of the genera Pseudomonas and Lactococcus, while in salted rennet cheese, Oxalobacteraceae, Janthinobacterium, Psychrobacter, and Pseudomonas species were noted. The effect of the starter culture on the production of aroma-related compounds responsible for cheese flavor was also studied by the solid-phase microextraction-gas chromatography-mass spectrometry technique. Kefir coculture also appeared to extend the shelf life of unsalted cheese. Spoilage of kefir cheese was observed on the 9th and 20th days of preservation at 10 and 5 degrees C, respectively, while spoilage in the corresponding rennet cheese was detected on the 7th and 16th days. Microbial counts during preservation of both types of unsalted cheese increased steadily and reached similar levels, with the exception of staphylococci, which were significantly lower in unsalted kefir cheese. All types of cheese produced with kefir as a starter were approved and accepted by the panel during the preliminary sensory evaluation compared to commercial feta-type cheese.

Animals↗

PubMed2004

Polymorphism of HLA class I genes in the Brazilian population from the Northeastern State of Pernambuco corroborates anthropological evidence of its origin.

The allelic distribution of human leukocyte antigen (HLA) class I genes (HLA-A, HLA-B, and HLA-Cw) of the population from the State of Pernambuco in Northeastern Brazil was studied in a sample of 101 healthy unrelated individuals. Low to medium resolution HLA class I typing was performed using polymerase chain reaction-amplified DNA hybridized to sequence specific primers (PCR-SSPs). Twenty allele groups were detected for HLA-A, 28 for HLA-B, and 14 for HLA-Cw. The most frequent alleles were HLA-A*02(0.2871), HLA-B*15(0.1238), and HLA-Cw*04(0.2277), and the most frequent genotypes were A*02/A*02(0.0990), B*15/B*15(0.0594), and Cw*04/Cw*04 and Cw*07/Cw*07, both with a frequency of 0.0792. The observed heterozygosity for the studied loci was 79.21% for HLA-A, 87.13% for HLA-B, and 77.23% for HLA-Cw. The most frequent haplotype was A*02-Cw*04-B*35(0.0485), which is also present in Western European, Amerindian, and Brazilian Mulatto populations, but absent in African populations. Taken together, these data corroborate the historic anthropological evidences of the origin of the Northeastern Brazilian population from Pernambuco.

Biological Evolution↗

PubMed2002

Removal of dyes from a synthetic textile dye effluent by biosorption on apple pomace and wheat straw.

This paper deals with two low-cost, locally available, renewable biosorbents; apple pomace and wheat straw for textile dye removal. Experiments at total dye concentrations of 10, 20, 30, 40, 50, 100, 150, and 200 mg/l were carried out with a synthetic effluent consisting of an equal mixture of five textile dyes. The effect of initial dye concentration, biosorbent particle size, quantity of biosorbent, effective adsorbance, dye removal and the applicability of the Langmuir and Freundlich isotherms were examined. One gram apple pomace was found to be a better biosorbent, removing 81% of dyes from the synthetic effluent at a particle size of 2 mm x 4 mm and 91% at 600 microm. Adsorption of dyes by apple pomace occurred at a faster rate in comparison to wheat straw. Both the isotherms were found to be applicable in the case of dye adsorption using apple pomace.

Adsorption↗

PubMed2002

Removal of dyes from an artificial textile dye effluent by two agricultural waste residues, corncob and barley husk.

The use of a previously untried biosorbent, barley husk, for dye removal is compared to corncob. The effectiveness of adsorption as a means of dye removal has made it an ideal alternative to other more costly treatments. This paper deals with two low-cost, renewable biosorbents, which are agroindustrial by-products, for textile dye removal. Experiments at total dye concentrations of 10, 20, 30, 40, 50, 100, 150, and 200 mg l(-1) were carried out with an artificial effluent consisting of an equal mixture of five textile dyes. The effects of initial dye concentration, biosorbent particle size, dose of biosorbent, effective adsorbance, and dye removal kinetics were examined. One gram (per 100 ml) of < or = 600 microm corncob was found to be effective in removing a high percentage of dyes at a rapid rate (92% in 48 h). One gram of I x 4 mm barley husk was found to be the most effective weight and particle size combination for the removal of dyes (92% in 48 h). The results illustrate how barley husk and corncob are effective biosorbents concerning the removal of textile dyes from effluent.

Adsorption↗

PubMed2002

High-temperature alcoholic fermentation of whey using Kluyveromyces marxianus IMB3 yeast immobilized on delignified cellulosic material.

A novel system for high-temperature alcoholic fermentation of whey is described. This system consists of Kluyveromyces marxianus yeast immobilized on delignified cellulosic material (DCM). The effect of pH, initial lactose concentration and temperature on the fermentation of a synthetic medium containing lactose was studied. Batch fermentations of whey were also carried out and the formation of volatile by-products was examined. The concentrations of higher alcohols were found to be in very low levels leading to a product of improved quality. The fermented whey had an improved characteristic aroma compared to unfermented whey. The possibility to use fermented whey as raw material for the production of a novel, low alcohol content drink was also investigated.

Alcohols↗

PubMed2002

Studies on desorption of individual textile dyes and a synthetic dye effluent from dye-adsorbed agricultural residues using solvents.

Two solvents, A and B (A: methanol, chloroform, water in the ratio 1:1:1; B: 50% methanol), were used to extract textile dyes adsorbed onto substrates for the purpose of future analyses of the amount of dyes degraded through solid state fermentation (SSF) using white rot fungi. Barley husk, apple pommace and corncob were separately soaked in five different dye solutions and a synthetic textile effluent. A maximum value of 93% desorption of Cibacron Red from corncob was achieved using solvent A. Barley husk was the only substrate from which the synthetic textile effluent could be desorbed, with 82% being recovered using solvent A.

Adsorption↗

PubMed2002

Effect of pretreatments of three waste residues, wheat straw, corncobs and barley husks on dye adsorption.

The removal of dyes (Cibacron Yellow C-2R, Cibacron Red C-2G, Cibacron Blue C-R, Remazol Black B and Remazol Red RB) from an aqueous solution has been discussed by adsorption which was examined on three different low cost pretreated agricultural residues viz., wheat straw, corncob and barley husk. The pretreatments were carried out in order to delignify, or to increase the surface area of the sorbents, and to study their effect on the rate and effective adsorption of dyes. Steam, alkali, ammonia steeping and milling were the pretreatments employed and compared with the untreated sorbents. A higher percentage of dye removal was achieved at a faster rate by the milled samples proving milling to be a better and more cost effective treatment, except for barley husk which had a higher percentage removal for the control.

Adsorption↗

PubMed2002

Resolution of (RS)-proglumide using lipase from Candida cylindraceae.

Proglumide is used in the treatment of neuropathic pain. It acts by inhibiting peptide cholecystokinin (CCK). Neural injury produces an elevation in plasma CCK. Proglumide has been also shown to augment the analgesic effect of sustained release morphine in neuropathic pain. Currently proglumide is administered as a racemic mixture. In the present study, an attempt is made to separate the racemic mixture of the drug using lipase obtained from Candida cylindracea by stereoselective esterification. Enzymatic stereoselective esterification was carried out in organic solvents. The resolution was studied using a chromatographic column with a chiral support and mass spectrometry. The reaction conditions for stereoselective esterification including amount of substrate, amount of enzyme, alcohol, solvent and temperature were optimised during the present investigation. Butanol and hexanol were found to be suitable for formation of S and R esters, respectively. Hexane was the best solvent for esterification and the optimum temperature was found to be 30 degreesC.

Analgesics↗

PubMed2001

Thermostable, alkalophilic and cellulase free xylanase production by Thermoactinomyces thalophilus subgroup C.

Thermoactinomyces thalophilus produced cellulase free extracellular endo-1,4-beta-xylanase (EC 3.2.1.8) at 50 degrees C and pH 8.5. Maximum xylanase production was achieved in fermentation medium using birchwood xylan as substrate after 96 h of growth at 50 degrees C. Other agricultural substrates such as wheat bran, wheat straw, sugarcane bagasse and cornstover produced less xylanase. The crude enzyme preparation from mutant T. thalophilus P2 grown under optimised fermentation conditions showed no cellulase contamination and maximum xylanase activity of 42 U/ml at 65%deg;C and pH 8.5-9.0. This enzyme with initial xylanase activity of 42 U/ml was found thermostable up to 65 degrees C and retaining 50% of its activity after its incubation for 125 min at 65 degrees C.

Journal Article↗

PubMed2001

Studies on the decolourisation of an artificial textile-effluent by white-rot fungi in N-rich and N-limited media.

Coriolopsis gallica and Phanerochaete chrysosporium were selected for their potential ability to degrade five dyes in an artificial effluent. Degradation experiments were carried out in N-rich (C:N ratio 11.6:1) and N-limited (116:1) conditions at an effluent concentration of 100 mg l(-1). P. chrysosporium decolourised 53.6% of the effluent in N-rich conditions and 48% in N-limited conditions. C. gallica decolourised 80.7% in N-rich conditions and 86.9% in N-limited conditions. Nitrogen supplementation improved enzyme activities and dye decolourisation for P. chrysosporium. Additional nitrogen increased enzyme activities for C. gallica but did not improve decolourisation. The results highlight the potential of C. gallica for textile dye degradation.

Biodegradation, Environmental↗

PubMed2001

Solid-state fermentation: a promising microbial technology for secondary metabolite production.

Solid state (substrate) fermentation (SSF) has been used successfully for the production of enzymes and secondary metabolites. These products are associated with the stationary phase of microbial growth and are produced on an industrial scale for use in agriculture and the treatment of disease. Many of these secondary metabolites are still produced by submerged liquid fermentations (SmF) even though production by this method has been shown to be less efficient than SSF. As large-scale production increases further, so do the costs and energy demands. SSF has been shown to produce a more stable product, requiring less energy, in smaller fermenters, with easier downstream processing measures. In this article we review an important area of biotechnology, since the recent evidence indicates that bacteria and fungi, growing under SSF conditions, are more than capable of supplying the growing global demand for secondary metabolites.

Anti-Bacterial Agents↗

PubMed2001

Microbial decolourisation and degradation of textile dyes.

Dyes and dyestuffs find use in a wide range of industries but are of primary importance to textile manufacturing. Wastewater from the textile industry can contain a variety of polluting substances including dyes. Increasingly, environmental legislation is being imposed to control the release of dyes, in particular azo-based compounds, into the environment. The ability of microorganisms to decolourise and metabolise dyes has long been known, and the use of bioremediation based technologies for treating textile wastewater has attracted interest. Within this review, we investigate the mechanisms by which diverse categories of microorganisms, such as the white-rot fungi and anaerobic bacterial consortia, bring about the degradation of dyestuffs.

Aerobiosis↗

PubMed2001

Remediation of dyes in textile effluent: a critical review on current treatment technologies with a proposed alternative.

The control of water pollution has become of increasing importance in recent years. The release of dyes into the environment constitutes only a small proportion of water pollution, but dyes are visible in small quantities due to their brilliance. Tightening government legislation is forcing textile industries to treat their waste effluent to an increasingly high standard. Currently, removal of dyes from effluents is by physio-chemical means. Such methods are often very costly and although the dyes are removed, accumulation of concentrated sludge creates a disposal problem. There is a need to find alternative treatments that are effective in removing dyes from large volumes of effluents and are low in cost, such as biological or combination systems. This article reviews the current available technologies and suggests an effective, cheaper alternative for dye removal and decolourisation applicable on large scale.

Adsorption↗

PubMed2001

Decolourisation of synthetic and spentwash melanoidins using the white-rot fungus Phanerochaete chrysosporium JAG-40.

Phanerochaete chrysosporium JAG-40 was isolated from the soil samples saturated with spilled molasses collected from a sugar mill. This isolate decolourised synthetic and natural melanoidins present in spentwash in liquid fermentation; up to 80% in 6 days at 30 degrees C under aerobic conditions. A large inoculum size stimulated fungal biomass production, but this gave less decolourisation of pigment; 5% w/v (dry weight) mycelial suspension was found optimum for maximum decolourisation in melanoidin medium supplemented with glucose and peptone. Gel-filtration chromatography showed that larger molecular weight fractions of melanoidin were decolourised more rapidly than small molecular weight fractions.

Alcoholic Beverages↗

PubMed2001

Decolourisation of molasses wastewater by cells of Pseudomonas fluorescens immobilised on porous cellulose carrier.

Pseudomonas fluorescens isolated from soil samples contaminated with molasses, decolourised molasses wastewater (MWW) samples up to 76% under non-sterile conditions in four days at 30 degrees C. Immobilised cells could be reused for decolourisation activity. However, in subsequent cycles, this was found to decrease from 76% to 50% and from 50% to 24%. Decolourisation activity was regenerated from 30% to 45% by recultivating the immobilised cells in a fresh growth medium. Cellulose carrier coated with collagen was found to be most effective carrier, which produced the highest decolourisation activity of 94% in a 4-day process. This carrier could be reused with 50% of the decolourisation activity retained until the seventh day.

Cells, Immobilized↗

PubMed2001

Biotransformation of cholesterol using Lactobacillus bulgaricus in a glucose-controlled bioreactor.

A novel single-step microbial transformation process for the production of testosterone from cholestrol by Lactobacillus bulgaricus in an aerated fermenter was investigated. The metabolism of glucose possibly supplying reducing power as NADH was necessary for the reduction of androst-4-en-3,17-dione (AD) to testosterone (TS). The growth period for the accumulation of testosterone in maximal amount and the residual glucose increased in parallel with the amount of glucose supplement in growth cultures. After the glucose in the fermentation culture was completely exhausted, most of the testosterone was oxidized to AD. Addition of a larger amount of glucose could prevent oxidation of testosterone to AD. The biotransformation of cholestrol was significantly increased in the presence of cyclodextrin (CD) in the fermenting medium. The addition of 0.1% CD to the growth medium facilitated the transport of the steroid substrate through the microbial cell wall.

Androstenedione↗

PubMed2001

Improving the quality of industrially important enzymes by directed evolution.

Directed evolution is a new process for developing industrially viable biocatalysts. This technique does not require a comprehensive knowledge of the relationships between sequence structure and function of proteins as required by protein engineering. It mimics the process of Darwinian evolution in a test tube combining random mutagenesis and recombination with screening or selection for enzyme variants that have the desired properties. Directed evolution helps in enhancing the enzyme performance both in natural and synthetic environments. This article reviews the process of directed evolution and its application to improve substrate specificity, activity, enantioselectivity and thermal stability.

Animals↗

PubMed2001

Biochemical markers in taxonomy of the genus Cunninghamella.

The chemical composition of fatty acids and ubiquinones was studied in 18 strains of Cunninghamella, to establish quantitative and qualitative differences within the genus. Fatty acids analysis has shown the presence of four groups. Ubiquinone analysis, through high performance liquid chromatography (HPLC), demonstrated the existence of three different groups based on the ubiquinone type. The average percentage of fatty acids of the species Cunninghamella elegans and Cunninghamella bertholletiae, show variations in linolenic and stearic acids, suggesting the possibility of differentiation between the two species.

Journal Article↗