Biomedical subjects

T Chakrabarti

Publications and source records attributed to T Chakrabarti.

At least 19 recordsLinked to original sources

PubMed2006

Aeromonas sharmana sp. nov., isolated from a warm spring.

A Gram-negative, facultatively anaerobic bacterial strain designated GPTSA-6(T) was isolated from a water sample collected from a warm spring in Assam, India. Preliminary analysis of the 16S rRNA gene sequence of this isolate revealed its affiliation to the family Aeromonadaceae. Detailed characterization using a polyphasic approach indicated that strain GPTSA-6(T) is most closely related to Aeromonas sobria but differs significantly from existing members of the genus Aeromonas. Analysis of the almost-complete (1430 nt) 16S rRNA gene sequence of this strain revealed that its closest relative (99.23 % similarity) is an uncultured bacterial clone, A-8, isolated from an algal bloom. Of the taxa with validly published names, Aeromonas sobria ATCC 43979(T) showed the highest level of sequence similarity (95.13 %) with respect to strain GPTSA-6(T), followed by Aeromonas molluscorum 848T(T) and Aeromonas popoffii LMG 17541(T) (95.04 % similarity in both cases). On the basis of the phenotypic, chemotaxonomic and phylogenetic data, it can be concluded that strain GPTSA-6(T) represents a novel species of the genus Aeromonas, for which the name Aeromonas sharmana sp. nov. is proposed. The type strain is GPTSA-6(T) (=MTCC 7090(T)=DSM 17445(T)).

Aeromonas↗

PubMed2006

Emticicia oligotrophica gen. nov., sp. nov., a new member of the family 'Flexibacteraceae', phylum Bacteroidetes.

An aquatic bacterium, strain GPTSA100-15T, was isolated on nutritionally poor medium TSBA100 (tryptic soy broth diluted 100 times and solidified with 1.5 % agarose) and characterized using a polyphasic approach. The isolate was unable to grow on commonly used nutritionally rich media such as tryptic soy agar, nutrient agar and Luria-Bertani agar. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the isolate was affiliated with the family 'Flexibacteraceae' in the phylum Bacteroidetes. Phylogenetically, it showed closest similarity (94.0 %) with an uncultured bacterial clone, HP1A92, detected in a sludge microbial community. Among the culturable bacteria, the isolate had highest 16S rRNA gene sequence similarity with Leadbetterella byssophila 4M15T (87.8 %). Sequence similarities with other members of the phylum Bacteroidetes were less than 85 %. The fatty acid profile of the isolate grown on TSBA100 indicated that the major fatty acid was iso-C15:0, which is also present in many members of the family 'Flexibacteraceae'. Cells of strain GPTSA100-15T are Gram-negative, strictly aerobic rods. The DNA G+C content of the isolate is 36.9 mol%. Results of phenotypic, chemotaxonomic and phylogenetic analyses clearly indicate that strain GPTSA100-15T represents a new genus within the family 'Flexibacteraceae'; the name Emticicia gen. nov. is proposed for the genus, with Emticicia oligotrophica sp. nov. as the type species. The type strain of Emticicia oligotrophica is GPTSA100-15T (=MTCC 6937T=DSM 17448T).

Bacterial Typing Techniques↗

PubMed2006

Effluviibacter roseus gen. nov., sp. nov., isolated from muddy water, belonging to the family "Flexibacteraceae".

A Gram-negative bacterial isolate (designated SRC-1(T)) was isolated from an occasional drainage system and characterized by a polyphasic approach to determine its taxonomic position. Phylogenetic analysis based on 16S rRNA gene sequences affiliated strain SRC-1(T) with the family "Flexibacteraceae" of the phylum Bacteroidetes. It showed greatest sequence similarity to Pontibacter actiniarum KMM 6156(T) (95.5 %) followed by Adhaeribacter aquaticus MBRG1.5(T) (89.0 %) and Hymenobacter roseosalivarius DSM 11622(T) (88.9 %), but it differed from these micro-organisms in many phenotypic characteristics. Strain SRC-1(T) was an obligate aerobe and its cells were non-motile, irregular rods. The major fatty acids included mainly unsaturated and hydroxy fatty acids, including 17 : 1 iso I/anteiso B (36.7 %), 15 : 0 iso (15.8 %) and 17 : 0 iso 3-OH (10.3 %), and the DNA G+C content was 59.5 mol%. From the phenotypic and genotypic analyses it was clear that strain SRC-1(T) was quite different from members other genera in the family '"Flexibacteraceae". Therefore we conclude that strain SRC-1(T) represents a novel genus, for which the name Effluviibacter gen. nov., containing a single species Effluviibacter roseus sp. nov., is proposed. The type species of the genus is Effluviibacter roseus, the type strain of which is strain SRC-1(T) (=MTCC 7260(T)=DSM 17521(T)).

Aerobiosis↗

PubMed2006

Flavobacterium indicum sp. nov., isolated from warm spring water in Assam, India.

A polyphasic taxonomic approach was employed to characterize a strain designated GPTSA100-9T, which was isolated from water sampled from a warm spring. The micro-organism, comprising Gram-negative, strictly aerobic rods, could not grow on nutritionally rich media such as tryptic soy broth. Analysis of the 16S rRNA gene sequence (1396 nt) of strain GPTSA100-9T revealed that it is a member of the genus Flavobacterium, sharing 99.8% sequence similarity with the CFB group bacterium strain A0653 (AF236016), 93.4% with '[Flexibacter] aurantiacus subsp. excathedrus' and 93.2-92.0% with Flavobacterium saliperosum, Flavobacterium soli, Flavobacterium aquatile and Flavobacterium columnare. The G+C content of the genomic DNA was 31.0 mol%. The major fatty acids of the strain grown on modified R2A agar were iso-C15:0 (18.5%), iso-C15:1 G (18.0%), summed feature 3 (iso-C15:0 2-OH and/or C16:1omega7c, 16.6%) and iso-C17:0 3-OH (9.0%). On the basis of phenotypic and genotypic characteristics, strain GPTSA100-9T represents a novel species of the genus Flavobacterium, for which the name Flavobacterium indicum sp. nov. is proposed. The type strain is GPTSA100-9T (=MTCC 6936T=DSM 17447T).

Anti-Bacterial Agents↗

PubMed2006

Oncogene-blocking therapies: new insights from conditional mouse tumor models.

Identification of oncogene dependent signaling pathways controlling aggressive tumor growth has led to the emergence of a new era of oncogene-blocking therapies, including Herceptin and Gleevec. In the recent years conditional mouse tumor models have been established that allow switching-off the expression of specific oncogenes controlling tumor growth. The results may have two important implications for oncogene-blocking therapies: (i) downregulation of oncogenes, for instance HER2, MYC, RAS, RAF, BCR-ABL or WNT1, usually leads to a rapid tumor remission. However, it was observed that the initial remission was followed by recurrent tumor growth in most studies. Interestingly, different oncogenes controlled tumor growth in the recurrent than in the primary tumors. This could explain the astonishing clinical observation that inhibitors of a broader spectrum of protein kinases (so-called: "dirty inhibitors") may be superior over highly specific substances. Due to their additional "unspecific" inhibition of a broader spectrum of kinases, they may hamper the escape mechanisms by antagonizing also the pathways controlling recurrent tumor growth. (ii) Experiments with cell systems that allow switching-on oncogene expression point to a so far possibly underestimated cancer drug target: the dormant tumor cell. Oncogene expression (for instance: NeuT or RAS) led to a phenomenon named oncogene-induced senescence or dormancy. Dormant cells are unresponsive to mitogenic stimuli. Importantly, such cells are not at all ready to die, but can remain viable for extended periods of time. Recently, dormant tumor cells have been shown to be more resistant to stresses such as hypoxia or exposure to cytostatic drugs. It still is a matter of debate if and under which conditions dormant tumor cells can be "kissed to life". If these cells contribute to carcinogenesis, it will be important to identify substances specifically killing senescent cells. This review will focus on the possible relevance of senescence both as a pre-oncogenic condition and also for therapy.

Animals↗

PubMed2005

Decolorisation, biodegradation and detoxification of benzidine based azo dye.

The present study deals with the decolorisation, biodegradation and detoxification of Direct Black-38, a benzidine based azo dye, by a mixed microbial culture isolated from an aerobic bioreactor treating textile wastewater. The studies revealed a biotransformation of Direct Black-38 into benzidine and 4-aminobiphenyl followed by complete decolorisation and biodegradation of these toxic intermediates. From cytotoxicity studies, it was concluded that detoxification of the dye took place after degradation of the toxic intermediates by the culture.

Adsorption↗

PubMed2005

Biodegradation of tech-hexachlorocyclohexane in a upflow anaerobic sludge blanket (UASB) reactor.

Biodegradability of technical grade hexachlorocyclohexane (tech-HCH) was studied in an upflow anaerobic sludge blanket reactor (UASB) under continuous mode of operation in concentration range of 100-200 mg/l and constant HRT of 48 h. At steady state operation more than 85% removal of tech-HCH (upto 175 mg/l concentration) and complete disappearance of beta-HCH was observed. Kinetic constants in terms of maximum specific tech-HCH utilization rate (k) and half saturation velocity constant (K(L)) were found to be 11.88 mg/g/day and 8.11 mg/g/day, respectively. The tech-HCH degrading seed preparation, UASB reactor startup and degradation in continuous mode of operation of the reactor is presented in this paper.

Anaerobiosis↗

PubMed2005

Activated sludge is a potential source for production of biodegradable plastics from wastewater.

Increased utilization of synthetic plastics caused severe environmental pollution due to their non-biodegradable nature. In the search for environmentally friendly materials to substitute for conventional plastics, different biodegradable plastics have been developed by microbial fermentations. However, limitations of these materials still exist due to high cost. This study aims at minimization of cost for the production of biodegradable plastics P(3HB) and minimization of environmental pollution. The waste biological sludge generated at wastewater treatment plants is used for the production of P(3HB) and wastewater is used as carbon source. Activated sludge was induced by controlling the carbon: nitrogen ratio to accumulate storage polymer. Initially polymer accumulation was studied by using different carbon and nitrogen sources. Maximum accumulation of polymer was observed with carbon source acetic acid and diammonium hydrogen phosphate (DAHP) as nitrogen source. Further studies were carried out to optimize the carbon: nitrogen ratios using acetic acid and DAHP. A maximum of 65.84% (w/w) P(3HB) production was obtained at C/N ratio of 50 within 96 hours of incubation.

Biodegradation, Environmental↗

PubMed2005

Planococcus stackebrandtii sp. nov., isolated from a cold desert of the Himalayas, India.

The taxonomic position of a bacterium isolated from a cold desert of the Himalayas, India, was analysed by using a polyphasic approach. The isolated strain, designated K22-03T, had phenotypic characteristics that matched those of the genus Planococcus and it represents a novel species. The almost-complete 16S rRNA gene sequence (1464 bases) of the novel strain was compared with those of previously studied Planococcus type strains and confirmed that the strain belongs to the genus Planococcus. 16S rRNA gene sequence analysis indicated that strain K22-03T differs from all other species of Planococcus by at least 2.5 %. DNA-DNA hybridization showed that it had low genomic relatedness with Planomicrobium mcmeekinii (MTCC 3704T, 23 %), Planococcus psychrophilus (MTCC 3812T, 61 %), Planococcus antarcticus (MTCC 3854T, 45 %) and Planomicrobium okeanokoites (MTCC 3703T, 51 %), the four species with which it was most closely related based on 16S rRNA gene sequence analysis (97-97.5 % similarity). Therefore, strain K22-03T should be recognized as a novel species, for which the name Planococcus stackebrandtii sp. nov. is proposed. The type strain is K22-03T (=MTCC 6226T=DSM 16419T=JCM 12481T).

Bacterial Typing Techniques↗

PubMed2005

Aquimonas voraii gen. nov., sp. nov., a novel gammaproteobacterium isolated from a warm spring of Assam, India.

A bacterial strain designated GPTSA 20(T), which was isolated from a warm spring in Assam, India, was characterized by using a polyphasic approach. The cells were Gram-negative, aerobic rods, which could not utilize or produce acid from most of the carbohydrates tested. The predominant fatty acids were C(15:0) iso (25.04%), C(17:1) iso omega9c (19.28%), C(16:0) iso (17.73%) and C(11:0) iso 3-OH (9.34%). The G+C content was 75 mol%. From 16S rRNA gene sequence analysis (1433 nucleotides, continuous stretch), it was confirmed that strain GPTSA 20(T) belonged to the class 'Gammaproteobacteria'. The closest 16S rRNA gene sequence similarity found (98.2%) was with an uncultured bacterium clone, NB-03 (accession no. AB117707), from an autotrophic nitrifying biofilm. Among culturable bacteria, the closest sequence similarities were with Fulvimonas soli (93.0%), Silanimonas lenta (92.8%), Thermomonas hydrothermalis (92.4%), Frateuria aurantia (91.9%), Rhodanobacter lindaniclasticus (91.9%), Thermomonas haemolytica (91.9%) and Pseudoxanthomonas taiwanensis (91.8%); similarities of less than 91.8% were obtained with other members of the class 'Gammaproteobacteria'. From the biochemical, physiological, chemotaxonomic and phylogenetic analysis, it was clear that strain GPTSA 20(T) was quite different from members of known genera of the class 'Gammaproteobacteria'. Therefore, it is proposed that strain GPTSA 20(T) represents a novel species within a new genus, with the name Aquimonas voraii gen. nov., sp. nov. The type strain is GPTSA 20(T) (=MTCC 6713(T)=JCM 12896(T)).

Bacterial Typing Techniques↗

PubMed2005

Paenibacillus assamensis sp. nov., a novel bacterium isolated from a warm spring in Assam, India.

A polyphasic approach was used to characterize a bacterium, GPTSA 11(T), isolated from a warm spring located in a reserve forest in Assam, India. The cells are Gram-variable, strictly aerobic, sporulating motile rods. The major fatty acids of the strain are C(15 : 0) anteiso (48.42 %), C(16 : 0) iso (11.59 %), C(16 : 1)omega11c (6.16 %), C(15 : 0) iso (6.03 %), C(17 : 0) anteiso (5.68 %) and C(16 : 1)omega7c alcohol (5.01 %). The presence of the fatty acid C(16 : 1)omega7c alcohol distinguishes this strain from other closely related species of the genus Paenibacillus. The strain contains MK-7 as the diagnostic menaquinone. The G+C content of the genomic DNA is 41.2 mol%. Analysis of the 16S rRNA gene sequence (1466 nt) revealed the presence of signature sequences PAEN 515F (5'-GAGTAACTGCTCTCGGAATGACGGTACTTGAGAAGAAAGCCCC-3') and PAEN 862F (5'-TCGATACCCTTGGTGCCGAAGT-3'), which were found in the species of the genus Paenibacillus surveyed by Shida et al. [Shida, O., Takagi, H., Kadowaki, K., Nakamura, L. K. & Komagata, K. (1997). Int J Syst Bacteriol 47, 289-298]. The sequence shows closest similarity (95.85 %) to that of Paenibacillus apiarius, followed by Paenibacillus alvei (94.34 %), Paenibacillus cineris (93.87 %), Paenibacillus favisporus (93.80 %), Paenibacillus chibensis (93.47 %) and Paenibacillus azoreducens (93.40 %). Biochemical, physiological, chemotaxonomic and phylogenetic analyses justify placement of the strain in the genus Paenibacillus but not within any existing species. It should, therefore, be considered as representing a novel species, for which the name Paenibacillus assamensis sp. nov. is proposed. The type strain is GPTSA 11T (=MTCC 6934T=JCM 13186T).

DNA, Bacterial↗

PubMed2004

Production of biodegradable plastics from activated sludge generated from a food processing industrial wastewater treatment plant.

Most of the excess sludge from a wastewater treatment plant (60%) is disposed by landfill. As a resource utilization of excess sludge, the production of biodegradable plastics using the sludge has been proposed. Storage polymers in bacterial cells can be extracted and used as biodegradable plastics. However, widespread applications have been limited by high production cost. In the present study, activated sludge bacteria in a conventional wastewater treatment system were induced, by controlling the carbon: nitrogen ratio to accumulate storage polymers. Polymer yield increased to a maximum 33% of biomass (w/w) when the C/N ratio was increased from 24 to 144, where as specific growth yield decreased with increasing C/N ratio. The conditions which are required for the maximum polymer accumulation were optimized and are discussed.

Bacteria↗

PubMed2004

Protective effect of distillate and redistillate of cow's urine in human polymorphonuclear leukocytes challenged with established genotoxic chemicals.

OBJECTIVE: From the ancient period cow's urine has been used as a medicine. In Veda, cow's urine was compared to the nectar. In Susrut, several medicinal properties of cow's urine have been mentioned and are known to cause weight loss, reversal of certain cardiac and kidney problems, indigestion, stomach ache, edema, etc. However, the literature and scripture did not mention the antigenotoxic properties of cow's urine. METHODS: In the present investigation, the antigenotoxic/antioxidant properties of cow's urine distillate and redistillate were studied in vitro. The antioxidant status and volatile fatty acid levels were determined. Actinomycin-D (0.1 micromol/L) and hydrogen peroxide (150 micromol/L) were used for inducing DNA strand break with 0.1% DMSO as negative control. Dose for the antigenotoxic effect of cow's urine was chosen from the dose response study carried out earlier. RESULTS: Both actinomycin-D and H202 caused statistically significant DNA unwinding of 80% & 75% respectively (P < 0.001) as revealed by fluorimetric analysis of DNA unwinding (FADU), and the damage could be protected with the redistilled cow's urine distillate (1, 50 & 100 microL) in simultaneous treatment with genotoxic chemicals. CONCLUSION: The redistillate of cow's urine was found to possess total antioxidant status of around 2.6 mmol, contributed mainly by volatile fatty acids (1500 mg/L) as revealed by the GC-MS studies. These fatty acids and other antioxidants might cause the observed protective effects.

Ammonia↗

PubMed2004

Genotoxicity of pesticide waste contaminated soil and its leachate.

OBJECTIVE: Improper land disposal of hazardous waste can result in leaching of hazardous constituents which may contaminate ground and surface water leading to adverse impact on human health and environment consequences. The present study utilized mammalian cell culture for the genotoxicity assessment of waste and its leachate. METHODS: Genotoxic potential and chemical analysis of pesticide derived tarry waste contaminated soil extract and its leachate was assessed using in vitro human lymphocyte cultures and GC-MS. RESULTS: The investigation revealed that the soil extract could cause significant to highly significant genotoxicity in the form of DNA strand break at 25 microL (P < 0.01), 50 microL, 100 microL and 200 microL (P < 0.001) and chromosomal aberration at 25 microL (P < 0.01) and 50 microL and 100 microL (P < 0.001). The leachate could cause significant DNA strand break and chromosomal aberration only at 100 microL and 200 microL (P < 0.01) dose levels. CONCLUSION: The genotoxicity observed is attributed to carbaril and tetra methyl naphthyl carbamate, the major ingredients of the extracts, as revealed by GC-MS.

Adult↗

PubMed2003

Preparation and characterization of biodegradable poly-3-hydroxybutyrate-starch blend films.

Bacterial polyesters have attracted much attention as biodegradable biocompatible polymers. Poly-3-hydroxybutyrate, a microbially produced thermoplastic, has similar material properties to polypropylene. Its potential application as biodegradable and biocompatible plastics is well documented. However, due to high cost it is used mainly in biomaterials for medical applications. Materials with useful properties may result from blending bacterial polyhydroxybutyrate (PHB) with other polymers. In this paper, the compatibility of PHB with starch for improved properties and cost reduction is discussed. The thermal and mechanical properties of the blended films were studied by means of thermogravimetry, differential scanning calorimetry and an automated material testing system. The results revealed that blend films had a single glass transition temperature for all the proportions of PHB:starch tested. The nature of all combinations was found to be crystalline. The tensile strength was optimum for the PHB:starch ratio of 0.7:0.3 (wt/wt). The variation in tensile strength, Young's modulus, extension needed to break, thermal stability, glass transition temperature, melting temperature, for the different proportions of PHB:starch are discussed.

Bacteria↗

PubMed2003

Kinetics of anaerobic biodegradation of resorcinol catechol and hydroquinone in upflow fixed film-fixed bed reactors.

Biodegradation of resorcinol, catechol and hydroquinone under anaerobic conditions was studied in identical upflow fixed film-fixed bed reactors. Kinetic constants; V(max) (maximum substrate utilization rate) and K(s) (Monod's half saturation constant) were determined for the three compounds using Lineweaver-Burk plot. V(max) for resorcinol was highest, followed by catechol and then by hydroquinone. When both resorcinol and catechol were fed to the resorcinol-acclimated reactor, resorcinol degradation was inhibited by catechol. The inhibition was of the uncompetitive type and V(max) for resorcinol was reduced by catechol.

Antioxidants↗

PubMed2003

Biotreatability and kinetics of UASB reactor to mixtures of chlorophenol pollutants.

In most natural ecosystems heterotrophic microorganisms encounter complex mixtures of carbon sources, each of which is present at a concentration of few micrograms per litre. This study examined the biotreatability and kinetics of an upflow anaerobic sludge blanket (UASB) reactor to complex mixtures of chlorophenols encountered in environmental conditions using on-line and off-line experimental studies. Results indicate that (1) steady-state concentration was quite lower (98.3 mg L(-1)) with complex mixture of chlorophenols than steady-state concentration achieved when only 2.4 dichlorophenol (124 mg L(-1)) was studied alone on the same reactor; (2) that toxic effects of chlorophenols increase with increasing concentrations of toxicant. (Onset of the inhibitory effect occurred at a lower concentration in multi-substrate than in single substrate utilization): (3) addition of alternative utilizable substrate can mitigate toxic effects and enhance degradation; (4) the relative concentration of substrate was critical in determining utilization patterns. HPLC analysis of off-line experimental samples resulted in a steady-state treatment efficiency of 68% for COD, 36% for 2-chlorophenol, 40.5% for 4-chlorophenol, 70.7% for 2,4-dichlorophenol, 53.2% for 2,4,6-trichlorophenol and 42% for pentachlorophenol in presence of glucose. Kinetic constant in terms of Vmax and Ks were determined. Ks for the five chlorophenols ranged between 0.016 and 0.117 kg m(-3) day(-1) while Vmax range between 0.056 and 0.244 kg m(-3) day(-1).

Bacteria, Anaerobic↗

PubMed2003

Apophysomyces elegans: an emerging zygomycete in India.

Apophysomyces elegans was considered a rare but medically important zygomycete. We analyzed the clinical records of eight patients from a single center in whom zygomycosis due to A. elegans was diagnosed over a span of 25 months. We also attempted a DNA-based method for rapid identification of the fungi and looked for interstrain polymorphism using microsattelite primers. Three patients had cutaneous and subcutaneous infections, three had isolated renal involvement, one had rhino-orbital tissue infection, and the final patient had a disseminated infection involving the spleen and kidney. Underlying illnesses were found in two patients, one with diabetes mellitus and the other with chronic alcoholism. A history of traumatic implantation was available for three patients. All except two of the patients responded to surgical and/or medical therapy; the diagnosis for the two exceptions was made at the terminal stage of infection. Restriction enzyme (MboI, MspI, HinfI) digestion of the PCR-amplified internal transcribed spacer region helped with the rapid and specific identification of A. elegans. The strains could be divided into two groups according to their patterns, with clustering into one pattern obtained by using microsatellite [(GTG)(5) and (GAC)(5)] PCR fingerprinting. The study highlights the epidemiology, clinical spectrum, and diagnosis of emerging A. elegans infections.

Adult↗