Armalendu Mandal

Bio: Armalendu Mandal is an academic researcher from University of Calcutta. The author has contributed to research in topics: Fluorescein. The author has an hindex of 1, co-authored 1 publications receiving 4 citations.

Studies on the effect of mercury and organomercurial on the growth and nitrogen fixation by mercury‐resistant Azotobacter strains

Abstract: Five nitrogen-fixing Azotobacter strains isolated from agricultural farms in West Bengal, India, were resistant to mercuric ion and organomercurials. Resistance of Hg-resistant bacteria to mercury compounds is mediated by the activities of mercuric reductase and organomercurial lyase in the presence of NADPH and GSH as cofactors. These bacteria showed an extended lag phase in the presence of 10-50 μmol l -1 HgCl 2 . Nitrogen-fixing ability of these isolates was slightly inhibited when the mercury-resistant bacterial cells were preincubated with 10 μmol l -1 HgCl 2 . Acetylene reduction by these bacteria was significantly inhibited (91-97%) by 50 μmol l -1 HgCl 2 . However, when GSH and NADPH were added to the acetylene reduction assay mixture containing 50 nmol l -1 HgCl 2 , only 42-50% inhibition of nitrogenase activity was observed. NADPH and GSH might have a role in suppressing the inhibition of N 2 -fixation in the presence of Hg compounds either by assisting Hg-detoxifying enzymes to lower Hg concentration in the assay mixture or by formation of adduct comprising Hg and GSH which is unable to inhibit nitrogen fixation.

Mercurochrome as an adjunct to local preoperative preparation in children undergoing hypospadias repair

Abstract: Objective To determine whether the local application of mercurochrome over genital skin before surgery, in addition to soap/water scrubs, can help to decrease the incidence of infection patients undergoing hypospadias repair, and thereby the incidence of fistula formation. Patients and methods The study comprised 44 consecutive boys undergoing primary or repeat surgery for hypospadias between October 1999 and April 2000. They were arbitrarily divided into two groups; group 1 received a conventional local scrub with soap/water 48 h before surgery and group 2, a conventional local scrub with soap/water was followed by a local application of 2% mercurochrome for 48 h before surgery. Both groups were comparable in age, location of the meatus and stage of repair. All patients were exposed to similar conditions during and after surgery. Urine, skin and wound swabs taken before during and after surgery were assessed microbiologically, using standard precautions. The incidence of infection and complications was then compared. Results Mercurochrome significantly decreased local infection, especially before surgery, but its effect in decreasing fistula formation, although appreciable, was not statistically significant. Conclusion The local application of mercurochrome after a soap/water scrub for at least 48 h before surgery is a simple, economic and effective means to decrease postoperative wound infection. Future studies are needed, keeping other determinants of fistula formation constant, to evaluate its role in decreasing fistula formation in patients undergoing hypospadias repair.

Enhanced elimination of HgCl2 from natural water by a broad-spectrum Hg-resistant Bacillus pasteurii strain DR2 in presence of benzene

Abstract: Mercury (Hg) compounds are extensively used in agriculture as seed-dressers and pesiticides, in hospitals as disinfectants, in sewage treatment and in industries including pulp and paper and chlor-alkali industries as chemical catalysts. Several thousand millions of tons of mercury are dispersed into the environment every year. Rain water washes mercury from soils and rocks. In aquatic environments sediments are the richest deposits of mercury compounds. The mutagenicity and teratogenicity of these Hg-containing compounds are well-documented. This paper reports on a study of the increased rate of the elimination of HgCl2 by Bacillus pasteurii strain DR2 from natural river water in the presence of organic compounds. This bacteria has the dual characteristics of elimination of mercury compounds and utilization of aromatic compounds in natural conditions. 19 refs., 3 figs., 1 tab.

Volatilization of mercury from natural water by a broad-spectrum Hg-resistant Bacillus pasteurii strain DR2

Abstract: A broad-spectrum mercury-resistant bacterial strain was isolated from contaminated water and was identified as Bacillus pasteurii strain DR2. It could volatilize Hg-compounds including organomercurials from its growth media. It utilized several aromatic compounds as a sole source of carbon. The bacterial strain eliminated HgCl2 from sterile river water and the presence of benzene, toluene, naphthalene and nitrobenzene at 1 mM concentration in the system increased the rate of mercury volatilization, the volatilization rate being highest with benzene. When 1.7×107 cells of this bacterial strain were added per ml of non-sterile water the bacterial strain volatilized more than 90 percent of mercury from mercuric chloride and organo-mercurials like PMA, thiomersol and methoxy ethyl mercuric chloride (MEMC). In the absence of this bacterial strain the volatilization of PMA and MEMC due to the presence of other Hg-resistant organisms in nonsterile polluted water ranged between 20–25 percent and of HgCl2 was about 40 percent. However, in the presence of B. pasteurii DR2 volatilization of these Hg-compounds from non-sterile water increased by 20–40 percent. In the presence of 1 mM benzene the rate of mercury volatilization was even higher. In all the cases the rate of volatilization was higher in the first seven days than in the next seven days.