Madhab Chattopadhyay - Academia.edu (original) (raw)

Papers by Madhab Chattopadhyay

doi: 10.3389/fmicb.2013.00047 The multifaceted roles of antibiotics and antibiotic resistance in ... more doi: 10.3389/fmicb.2013.00047 The multifaceted roles of antibiotics and antibiotic resistance in nature

Use of antibiotics as feed additives: a burning question

Journal of Pharmacy and Pharmacology, 1993

In the thought provoking-letter published in the April 1992 issue of this journal, R. A. Brown ha... more In the thought provoking-letter published in the April 1992 issue of this journal, R. A. Brown has rightly pointed out our lack of knowledge in the reaction mechanism of Lowry’s method of protein estimation (Lowry et al 1951). Though the necessity of learning the theoretical background of such a widely used laboratory technique need hardly be emphasized, surprisingly it is often ignored. We have carried out a thorough literature survey on the mechanism of the Lowry reaction. This letter deals with a brief discussion on this aspect. This method involves the pretreatment of protein with alkaline copper sulphate in the presence of tartarate followed by the addition of Folin’s phenol reagent. In a dipeptide copper complex, the copper atom is held in a coplanar tridentate chelate involving the free amino nitrogen, the peptide bond nitrogen and the free carboxyl group. The additional presence of a side-chain nitrogen, as in asparagine and histidine, helps in the formation of a more stable, quadridentate chelate. In a tripeptide copper complex, the quandridentate chelate can be formed with the two available peptide bonds without the participation of a functional group. The chelated protein then reduces the Folin’s reagent, a mixture of phosphomolybdic-tungstic acids (Creighton 1984). This reduction results in the loss of one, two or three oxygen atoms from the tungstates and molybdates to produce several reduced species with a characteristic blue colour (Amax 745-750 nm). The ability to form a stable chelate determines the rate of electron removal, 1.e. the reducing potential of the protein. The Fohn reagent has a half-life of 8 s at the alkaline pH of the reaction (pH = 10) and therefore rapid electron transfer from the protein is crucial for ultimate colour yield. Thus it is evident that the whole peptide backbone is involved in the colour formation when pretreated with copper. Only the chromogenic amino acids such as tyrosine, tryptophan, cysteine and to a lesser extent histidine can contribute to the colour yield without copper-pretreatment (Chou & Goldstein 1960). DAmino acids behave in an identical manner to their L-counterparts. Pretreatment with copper does not affect the colour formation by tyrosine or tryptophan, but colour formation is drastically reduced for cysteine and peptide containing cysteine because the sulphydryl group is blocked by copper ion. It is interesting to note that penicillin, which contains a dipeptide of cysteine and valine with a blocked amino group, yielded more colour than the corresponding free dipeptide; however, when it is cleaved by /?-lactamase to give two amino acids linked through sulphur ofcysteine, the colour yield is high. Desthiopenicillin did not give any colour and penicillamine (PP-dimethylcysteine) yielded less colour than cysteine confirming the involvement of the sulphydryl group in colour production. All dipeptides are chromogenic in the presence of copper and the response is enhanced in the presence of side-chain amino or carboxyl groups. Particularly chromogenic are dipeptides containing histidine, arginine or glutamic acids residues. Tripeptides are highly chromogenic even in the absence of functional side chains. Sequences of the type ValGluAla and ValGluAlaLeu are chromogenic although their contribution to the total colour yield is small. Thus a number of features contribute to the total colour yield giving the technique a broad specificity. It is noteworthy that the colour formation is susceptible to interference by potassium ions (Vallejo & Lagunas 1970), magnesium ions (Kuno & Kihara 1967), EDTA (Neurath 1966), Tris (Kuno & Kihara 1967), thiol reagents (Vallejo & Lagunas 1970) and carbohydrates (Lo & Stelson 1972). Aromatic amino acids, uric acid, guanine and xanthine also interfere in the f olin phenol method. As a remedy Bennet (1967) recommended precipitation of protein with trichloroacetic acid and redissolving the precipitate before colour formation. For protein estimation of cell membrane components Parnaik et al(1983) recommended addition of sodium dodecylsulphate just before the addition of Folin’s reagent.

42-43A number of organisms in the polar regions have been found to be antibiotic-resistant

Resonance, 2009

L ife o n ea rth w ith o u t w a te r is d i± cu lt to im a g in e. W e m a y su rv iv e w ith o ... more L ife o n ea rth w ith o u t w a te r is d i± cu lt to im a g in e. W e m a y su rv iv e w ith o u t fo o d fo r tw o m o n th s b u t w e c a n n o t su rv iv e w ith o u t w a te r fo r m o re th a n a w ee k . W a te r m a k e s u p n e a rly 6 5 % o f th e c o n stitu e n ts o f th e b o d y. O u r m e ta b o lism is c ru c ia lly d e p en d e n t o n w a te r. W e m a y d ie if w e lo se e v e n 1 4 % o f th e w a ter c o n te n t fro m o u r b o d y .

Biotechnology Letters, 1995

Mutants of Escherichia coli K-12 resistant to a threonine analogue (ot-amino-I]-hydroxy valeric a... more Mutants of Escherichia coli K-12 resistant to a threonine analogue (ot-amino-I]-hydroxy valeric acid) were predominantly resistant to ethionine and overproduced both threonine and methionine (2 mg/ml each). Novelty of the mutants is discussed.

Since, like other osmolytes, proline can act as a protein stabilizer, we investigated the thermop... more Since, like other osmolytes, proline can act as a protein stabilizer, we investigated the thermoprotectant properties of proline in vitro and in vivo. In vivo, elevated proline pools in Escherichia coli (obtained by altering the feedback inhibition by proline of ␥-glutamylkinase, the first enzyme of the proline biosynthesis pathway) restore the viability of a dnaK-deficient mutant at 42°C, suggesting that proline can act as a thermoprotectant for E. coli cells. Furthermore, analysis of aggregated proteins in the dnaK-deficient strain at 42°C by twodimensional gel electrophoresis shows that high proline pools reduce the protein aggregation defect of the dnaK-deficient strain. In vitro, like other "chemical chaperones," and like the DnaK chaperone, proline protects citrate synthase against thermodenaturation and stimulates citrate synthase renaturation after urea denaturation. These results show that a protein aggregation defect can be compensated for by a single mutation in an amino acid biosynthetic pathway and that an ubiquitously producible chemical chaperone can compensate for a defect in one of the major chaperones involved in protein folding and aggregation.

Resonance, 2015

Outer membrane vesicles are nano-sized spheres produced predominantly by gram-negative bacteria. ... more Outer membrane vesicles are nano-sized spheres produced predominantly by gram-negative bacteria. They play a significant role in cell-to-cell communication, virulence, nutrition and protection of the bacterial cells from various stress factors. Recent evidences also underscore their involvement in antibiotic-resistance of bacteria. In this article, we discuss the physiological importance of these vesicles with potential use in the development of vaccines and drug delivery.

Frontiers in Microbiology, 2013

Antibiotics are chemotherapeutic agents, which have been a very powerful tool in the clinical man... more Antibiotics are chemotherapeutic agents, which have been a very powerful tool in the clinical management of bacterial diseases since the 1940s. However, benefits offered by these magic bullets have been substantially lost in subsequent days following the widespread emergence and dissemination of antibiotic-resistant strains. While it is obvious that excessive and imprudent use of antibiotics significantly contributes to the emergence of resistant strains, antibiotic resistance is also observed in natural bacteria of remote places unlikely to be impacted by human intervention. Both antibiotic biosynthetic genes and resistance-conferring genes have been known to evolve billions of years ago, long before clinical use of antibiotics. Hence it appears that antibiotics and antibiotics resistance determinants have some other roles in nature, which often elude our attention because of overemphasis on the therapeutic importance of antibiotics and the crisis imposed by the antibiotic resistance in pathogens. In the natural milieu, antibiotics are often found to be present in sub-inhibitory concentrations acting as signaling molecules supporting the process of quorum sensing and biofilm formation. They also play an important role in the production of virulence factors and influence host-parasite interactions (e.g., phagocytosis, adherence to the target cell, and so on). The evolutionary and ecological aspects of antibiotics and antibiotic resistance in the naturally occurring microbial community are little understood. Therefore, the actual role of antibiotics in nature warrants in-depth investigations. Studies on such an intriguing behavior of the microorganisms promise insight into the intricacies of the microbial physiology and are likely to provide some lead in controlling the emergence and subsequent dissemination of antibiotic resistance. This article highlights some of the recent findings on the role of antibiotics and the genes that confer resistance to antibiotics in nature.

Frontiers in Microbiology, 2014

The major carotenoid pigments of an Antarctic psychrotolerant bacterium, Sphingobacterium antarct... more The major carotenoid pigments of an Antarctic psychrotolerant bacterium, Sphingobacterium antarcticus, and a mesophilic bacterium, Sphingobacterium multivorum, were identified as zeaxanthin, β-cryptoxanthin, and β-carotene. Analysis was based on ultraviolet-visible spectroscopy, mass spectroscopy, and reversed-phase HPLC. Photoacoustic spectroscopy of intact bacterial cells revealed that the bulk of the pigments in S. antarcticus and S. multivorum was associated with the cell membrane. In vitro studies with synthetic membranes of phosphatidylcholine demonstrated that the major pigment was bound to the membranes and decreased their fluidity. The relative amounts of polar pigments were higher in cells grown at 5°C than in cells grown at 25°C. In the mesophilic strain, the synthesis of polar carotenoids was quantitatively less than that of the psychrotolerant strain.

Proceedings of the Indian National Science Academy

This review explores the bacterial diversity of Antarctica, Arctic, Himalayan glaciers and Strato... more This review explores the bacterial diversity of Antarctica, Arctic, Himalayan glaciers and Stratosphere with a view to establish their abundance, their identity and capability to adapt to cold temperatures. It also highlights the unique survival strategies of these psychrophiles at the molecular, cellular, tissue and organism level. It also establishes their utility to mankind in the spheres of health, agriculture and medicine. A major part of the review includes studies carried by scientists in India in the above extreme cold habitats.

Grand Challenges in Biology and Biotechnology, 2016

Biochem Biophys Res Commun, 1996

BioMed research international, 2015

Frontiers in Microbiology, 2015

The name of the second author should be read as Medicharla V. Jagannadham. The original article w... more The name of the second author should be read as Medicharla V. Jagannadham. The original article was updated. Conflict of Interest Statement: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Frontiers in Microbiology, 2015

doi: 10.3389/fmicb.2013.00047 The multifaceted roles of antibiotics and antibiotic resistance in ... more doi: 10.3389/fmicb.2013.00047 The multifaceted roles of antibiotics and antibiotic resistance in nature

Use of antibiotics as feed additives: a burning question

Journal of Pharmacy and Pharmacology, 1993

In the thought provoking-letter published in the April 1992 issue of this journal, R. A. Brown ha... more In the thought provoking-letter published in the April 1992 issue of this journal, R. A. Brown has rightly pointed out our lack of knowledge in the reaction mechanism of Lowry’s method of protein estimation (Lowry et al 1951). Though the necessity of learning the theoretical background of such a widely used laboratory technique need hardly be emphasized, surprisingly it is often ignored. We have carried out a thorough literature survey on the mechanism of the Lowry reaction. This letter deals with a brief discussion on this aspect. This method involves the pretreatment of protein with alkaline copper sulphate in the presence of tartarate followed by the addition of Folin’s phenol reagent. In a dipeptide copper complex, the copper atom is held in a coplanar tridentate chelate involving the free amino nitrogen, the peptide bond nitrogen and the free carboxyl group. The additional presence of a side-chain nitrogen, as in asparagine and histidine, helps in the formation of a more stable, quadridentate chelate. In a tripeptide copper complex, the quandridentate chelate can be formed with the two available peptide bonds without the participation of a functional group. The chelated protein then reduces the Folin’s reagent, a mixture of phosphomolybdic-tungstic acids (Creighton 1984). This reduction results in the loss of one, two or three oxygen atoms from the tungstates and molybdates to produce several reduced species with a characteristic blue colour (Amax 745-750 nm). The ability to form a stable chelate determines the rate of electron removal, 1.e. the reducing potential of the protein. The Fohn reagent has a half-life of 8 s at the alkaline pH of the reaction (pH = 10) and therefore rapid electron transfer from the protein is crucial for ultimate colour yield. Thus it is evident that the whole peptide backbone is involved in the colour formation when pretreated with copper. Only the chromogenic amino acids such as tyrosine, tryptophan, cysteine and to a lesser extent histidine can contribute to the colour yield without copper-pretreatment (Chou & Goldstein 1960). DAmino acids behave in an identical manner to their L-counterparts. Pretreatment with copper does not affect the colour formation by tyrosine or tryptophan, but colour formation is drastically reduced for cysteine and peptide containing cysteine because the sulphydryl group is blocked by copper ion. It is interesting to note that penicillin, which contains a dipeptide of cysteine and valine with a blocked amino group, yielded more colour than the corresponding free dipeptide; however, when it is cleaved by /?-lactamase to give two amino acids linked through sulphur ofcysteine, the colour yield is high. Desthiopenicillin did not give any colour and penicillamine (PP-dimethylcysteine) yielded less colour than cysteine confirming the involvement of the sulphydryl group in colour production. All dipeptides are chromogenic in the presence of copper and the response is enhanced in the presence of side-chain amino or carboxyl groups. Particularly chromogenic are dipeptides containing histidine, arginine or glutamic acids residues. Tripeptides are highly chromogenic even in the absence of functional side chains. Sequences of the type ValGluAla and ValGluAlaLeu are chromogenic although their contribution to the total colour yield is small. Thus a number of features contribute to the total colour yield giving the technique a broad specificity. It is noteworthy that the colour formation is susceptible to interference by potassium ions (Vallejo & Lagunas 1970), magnesium ions (Kuno & Kihara 1967), EDTA (Neurath 1966), Tris (Kuno & Kihara 1967), thiol reagents (Vallejo & Lagunas 1970) and carbohydrates (Lo & Stelson 1972). Aromatic amino acids, uric acid, guanine and xanthine also interfere in the f olin phenol method. As a remedy Bennet (1967) recommended precipitation of protein with trichloroacetic acid and redissolving the precipitate before colour formation. For protein estimation of cell membrane components Parnaik et al(1983) recommended addition of sodium dodecylsulphate just before the addition of Folin’s reagent.

42-43A number of organisms in the polar regions have been found to be antibiotic-resistant

Resonance, 2009

L ife o n ea rth w ith o u t w a te r is d i± cu lt to im a g in e. W e m a y su rv iv e w ith o ... more L ife o n ea rth w ith o u t w a te r is d i± cu lt to im a g in e. W e m a y su rv iv e w ith o u t fo o d fo r tw o m o n th s b u t w e c a n n o t su rv iv e w ith o u t w a te r fo r m o re th a n a w ee k . W a te r m a k e s u p n e a rly 6 5 % o f th e c o n stitu e n ts o f th e b o d y. O u r m e ta b o lism is c ru c ia lly d e p en d e n t o n w a te r. W e m a y d ie if w e lo se e v e n 1 4 % o f th e w a ter c o n te n t fro m o u r b o d y .

Biotechnology Letters, 1995

Mutants of Escherichia coli K-12 resistant to a threonine analogue (ot-amino-I]-hydroxy valeric a... more Mutants of Escherichia coli K-12 resistant to a threonine analogue (ot-amino-I]-hydroxy valeric acid) were predominantly resistant to ethionine and overproduced both threonine and methionine (2 mg/ml each). Novelty of the mutants is discussed.

Since, like other osmolytes, proline can act as a protein stabilizer, we investigated the thermop... more Since, like other osmolytes, proline can act as a protein stabilizer, we investigated the thermoprotectant properties of proline in vitro and in vivo. In vivo, elevated proline pools in Escherichia coli (obtained by altering the feedback inhibition by proline of ␥-glutamylkinase, the first enzyme of the proline biosynthesis pathway) restore the viability of a dnaK-deficient mutant at 42°C, suggesting that proline can act as a thermoprotectant for E. coli cells. Furthermore, analysis of aggregated proteins in the dnaK-deficient strain at 42°C by twodimensional gel electrophoresis shows that high proline pools reduce the protein aggregation defect of the dnaK-deficient strain. In vitro, like other "chemical chaperones," and like the DnaK chaperone, proline protects citrate synthase against thermodenaturation and stimulates citrate synthase renaturation after urea denaturation. These results show that a protein aggregation defect can be compensated for by a single mutation in an amino acid biosynthetic pathway and that an ubiquitously producible chemical chaperone can compensate for a defect in one of the major chaperones involved in protein folding and aggregation.

Resonance, 2015

Outer membrane vesicles are nano-sized spheres produced predominantly by gram-negative bacteria. ... more Outer membrane vesicles are nano-sized spheres produced predominantly by gram-negative bacteria. They play a significant role in cell-to-cell communication, virulence, nutrition and protection of the bacterial cells from various stress factors. Recent evidences also underscore their involvement in antibiotic-resistance of bacteria. In this article, we discuss the physiological importance of these vesicles with potential use in the development of vaccines and drug delivery.

Frontiers in Microbiology, 2013

Antibiotics are chemotherapeutic agents, which have been a very powerful tool in the clinical man... more Antibiotics are chemotherapeutic agents, which have been a very powerful tool in the clinical management of bacterial diseases since the 1940s. However, benefits offered by these magic bullets have been substantially lost in subsequent days following the widespread emergence and dissemination of antibiotic-resistant strains. While it is obvious that excessive and imprudent use of antibiotics significantly contributes to the emergence of resistant strains, antibiotic resistance is also observed in natural bacteria of remote places unlikely to be impacted by human intervention. Both antibiotic biosynthetic genes and resistance-conferring genes have been known to evolve billions of years ago, long before clinical use of antibiotics. Hence it appears that antibiotics and antibiotics resistance determinants have some other roles in nature, which often elude our attention because of overemphasis on the therapeutic importance of antibiotics and the crisis imposed by the antibiotic resistance in pathogens. In the natural milieu, antibiotics are often found to be present in sub-inhibitory concentrations acting as signaling molecules supporting the process of quorum sensing and biofilm formation. They also play an important role in the production of virulence factors and influence host-parasite interactions (e.g., phagocytosis, adherence to the target cell, and so on). The evolutionary and ecological aspects of antibiotics and antibiotic resistance in the naturally occurring microbial community are little understood. Therefore, the actual role of antibiotics in nature warrants in-depth investigations. Studies on such an intriguing behavior of the microorganisms promise insight into the intricacies of the microbial physiology and are likely to provide some lead in controlling the emergence and subsequent dissemination of antibiotic resistance. This article highlights some of the recent findings on the role of antibiotics and the genes that confer resistance to antibiotics in nature.

Frontiers in Microbiology, 2014

The major carotenoid pigments of an Antarctic psychrotolerant bacterium, Sphingobacterium antarct... more The major carotenoid pigments of an Antarctic psychrotolerant bacterium, Sphingobacterium antarcticus, and a mesophilic bacterium, Sphingobacterium multivorum, were identified as zeaxanthin, β-cryptoxanthin, and β-carotene. Analysis was based on ultraviolet-visible spectroscopy, mass spectroscopy, and reversed-phase HPLC. Photoacoustic spectroscopy of intact bacterial cells revealed that the bulk of the pigments in S. antarcticus and S. multivorum was associated with the cell membrane. In vitro studies with synthetic membranes of phosphatidylcholine demonstrated that the major pigment was bound to the membranes and decreased their fluidity. The relative amounts of polar pigments were higher in cells grown at 5°C than in cells grown at 25°C. In the mesophilic strain, the synthesis of polar carotenoids was quantitatively less than that of the psychrotolerant strain.

Proceedings of the Indian National Science Academy

This review explores the bacterial diversity of Antarctica, Arctic, Himalayan glaciers and Strato... more This review explores the bacterial diversity of Antarctica, Arctic, Himalayan glaciers and Stratosphere with a view to establish their abundance, their identity and capability to adapt to cold temperatures. It also highlights the unique survival strategies of these psychrophiles at the molecular, cellular, tissue and organism level. It also establishes their utility to mankind in the spheres of health, agriculture and medicine. A major part of the review includes studies carried by scientists in India in the above extreme cold habitats.

Grand Challenges in Biology and Biotechnology, 2016

Biochem Biophys Res Commun, 1996

BioMed research international, 2015

Frontiers in Microbiology, 2015

The name of the second author should be read as Medicharla V. Jagannadham. The original article w... more The name of the second author should be read as Medicharla V. Jagannadham. The original article was updated. Conflict of Interest Statement: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Frontiers in Microbiology, 2015