Deepak Chauhan - Academia.edu (original) (raw)

Papers by Deepak Chauhan

Letters in Applied Microbiology, 2013

Of the twenty-three morphotypes of yeasts isolated from soil capable of utilizing pectin as sole ... more Of the twenty-three morphotypes of yeasts isolated from soil capable of utilizing pectin as sole carbon source at 6°C, two yeast isolates, one psychrotolerant (PT1) and one psychrophilic (SPY11), were selected according to their ability to secrete pectinolytic enzymes under some oenological conditions (temperature 6 and 12°C and pH 3.5) and ability or inability to grow above 20°C, respectively. As compared to their optimal activity, the three pectinolytic enzymes viz., pectin methyl esterase (PME), endopolygalacturonase (endo-PG) and exopolygalacturonase (exo-PG) isolated and assayed at pH 3.5 from PT1 were found to retain 39, 60 and 60% activity at 12°C and 40, 79 and 74% activity at 28°C, respectively. Likewise, the enzymes PME and endo-PG at pH 3.5 from SPY11 displayed 46 and 86% activity at 12°C and 50 and 60% activity at 28°C, respectively. All these enzymes showed 20-90% of residual activity at pH 3.5 and 6°C. The yeast isolates PT1 and SPY11 were identified as Rhodotorula mucilaginosa and Cystofilobasidium capitatum, respectively, on the basis of morphological, physiological and molecular characteristics. This study presents the first report on pectinolytic activities under major oenological conditions from psychrotolerant isolate R. mucilaginosa PT1 and psychrophilic isolate C. capitatum SPY11. The cold-active pectinolytic enzymes (PME, endo-PG and exo-PG) from the newly isolated and identified psychrophilic yeast Cystofilobasidium capitatum SPY11 and psychrotolerant yeast Rhodotorula mucilaginosa PT1that exhibited 50-80% of their optimum activity under some major oenological conditions pH (3.5) and temperatures (6 and 12°C) could be applied to wine production and juice clarification at low temperature. The psychrotrophic yeasts themselves could be applied to cold process for the production of enzymes thus saving cost of energy and protecting process from contamination.

Proceedings of the National Academy of Sciences, India Section B: Biological Sciences, 2019

Prompted by multiple applications of laccases, the fungi yielding enzyme with wider geographical ... more Prompted by multiple applications of laccases, the fungi yielding enzyme with wider geographical applicability and other novel features was explored from Jaisalmer desert (India). One of the isolates TTF6 yielded laccase exhibiting novel many-fold amplification in activity in the presence of lead (Pb) and tolerance to Na. The peroxide-free enzyme showed apparent molecular mass 40 kDa, activity from 10 to 80 °C, temperature optima at 60 °C and pH optima at 5.0. It was highly thermostable losing only 22 and 44% of its maximal activity in 24 and 48 h, respectively, with a half-life of 60 h at 60 °C. It was found resistant to studied metals including Cu and Zn and showed tolerance to many organic solvents. The enzyme was produced best in Olga medium and induced by ethanol and copper sulfate but not by guaiacol, though guaiacol could be utilized as substrate. The partially purified enzyme decolorized selected synthetic dyes at 20–40 °C, the decolorization rate, however, was not affected by Pb. The fungus was identified on the basis of morphological and ITS sequence characteristics as A. nidulans. This is the first report of a Pb-activated laccase and the sixth phenol oxidase from A. nidulans reported so far.

African Journal of Biotechnology, May 28, 2014

Letters in Applied Microbiology, 2013

Of the twenty-three morphotypes of yeasts isolated from soil capable of utilizing pectin as sole ... more Of the twenty-three morphotypes of yeasts isolated from soil capable of utilizing pectin as sole carbon source at 6°C, two yeast isolates, one psychrotolerant (PT1) and one psychrophilic (SPY11), were selected according to their ability to secrete pectinolytic enzymes under some oenological conditions (temperature 6 and 12°C and pH 3.5) and ability or inability to grow above 20°C, respectively. As compared to their optimal activity, the three pectinolytic enzymes viz., pectin methyl esterase (PME), endopolygalacturonase (endo-PG) and exopolygalacturonase (exo-PG) isolated and assayed at pH 3.5 from PT1 were found to retain 39, 60 and 60% activity at 12°C and 40, 79 and 74% activity at 28°C, respectively. Likewise, the enzymes PME and endo-PG at pH 3.5 from SPY11 displayed 46 and 86% activity at 12°C and 50 and 60% activity at 28°C, respectively. All these enzymes showed 20-90% of residual activity at pH 3.5 and 6°C. The yeast isolates PT1 and SPY11 were identified as Rhodotorula mucilaginosa and Cystofilobasidium capitatum, respectively, on the basis of morphological, physiological and molecular characteristics. This study presents the first report on pectinolytic activities under major oenological conditions from psychrotolerant isolate R. mucilaginosa PT1 and psychrophilic isolate C. capitatum SPY11. The cold-active pectinolytic enzymes (PME, endo-PG and exo-PG) from the newly isolated and identified psychrophilic yeast Cystofilobasidium capitatum SPY11 and psychrotolerant yeast Rhodotorula mucilaginosa PT1that exhibited 50-80% of their optimum activity under some major oenological conditions pH (3.5) and temperatures (6 and 12°C) could be applied to wine production and juice clarification at low temperature. The psychrotrophic yeasts themselves could be applied to cold process for the production of enzymes thus saving cost of energy and protecting process from contamination.

Proceedings of the National Academy of Sciences, India Section B: Biological Sciences, 2019

Prompted by multiple applications of laccases, the fungi yielding enzyme with wider geographical ... more Prompted by multiple applications of laccases, the fungi yielding enzyme with wider geographical applicability and other novel features was explored from Jaisalmer desert (India). One of the isolates TTF6 yielded laccase exhibiting novel many-fold amplification in activity in the presence of lead (Pb) and tolerance to Na. The peroxide-free enzyme showed apparent molecular mass 40 kDa, activity from 10 to 80 °C, temperature optima at 60 °C and pH optima at 5.0. It was highly thermostable losing only 22 and 44% of its maximal activity in 24 and 48 h, respectively, with a half-life of 60 h at 60 °C. It was found resistant to studied metals including Cu and Zn and showed tolerance to many organic solvents. The enzyme was produced best in Olga medium and induced by ethanol and copper sulfate but not by guaiacol, though guaiacol could be utilized as substrate. The partially purified enzyme decolorized selected synthetic dyes at 20–40 °C, the decolorization rate, however, was not affected by Pb. The fungus was identified on the basis of morphological and ITS sequence characteristics as A. nidulans. This is the first report of a Pb-activated laccase and the sixth phenol oxidase from A. nidulans reported so far.

African Journal of Biotechnology, May 28, 2014