01407nas a2200205   4500008004100000022001400041245007000055210006900125260007400194300001400268490000700282520066700289653002300956653002200979653002201001653002501023100002401048700002501072856010401097       2008                        eng d  a0141-549200aHexavalent chromate reduction by immobilized streptomyces griseus0 aHexavalent chromate reduction by immobilized streptomyces griseu  aVAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDSbSPRINGERcJUN  a1005-10100 v303 a<p>Hexavalent chromium, which is a mutagen and carcinogen, was efficiently reduced by Streptomyces griseus. This activity was associated with the cell. Cr6+ reduction by free as well as immobilized cells was studied: cells in PVA- alginate had the highest ( 100%) Cr6+ removal efficiency in 24 h with reduction rates similar to free cells. Immobilized cells completely reduced 25 mg Cr6+ l(-1) in 24 h. PVA- alginate immobilized cells could be reused four times to completely reduce 25 mg Cr6+ l(-1) in 24 h each time. Chromate in a simulated effluent containing Cu2+, Mg2+, Mn2+ and Zn2+ was completely reduced by PVA- alginate immobilized cells within 9 h.</p>10aChromate reduction10aImmobilized cells10apolyvinyl alcohol10aStreptomyces griseus1 aPoopal, Ashwini, C.1 aLaxman, Ryali, Seeta  uhttps://library.ncl.res.in/content/hexavalent-chromate-reduction-immobilized-streptomyces-griseus-001723nas a2200217   4500008004100000022001400041245008800055210006900143260007400212300001000286490000700296520091600303653001901219653002301238653002201261653003101283653002501314100002401339700002501363856011701388       2009                        eng d  a0141-549200aChromate reduction by PVA-alginate immobilized streptomyces griseus in a bioreactor0 aChromate reduction by PVAalginate immobilized streptomyces grise  aVAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDSbSPRINGERcJAN  a71-760 v313 a<p>Microbial reduction of toxic Cr(6+) to the less toxic Cr(3+) is potentially a useful bioremediation process. Among the matrices tested for whole cell immobilization of an efficient chromate-reducing Streptomyces griseus strain, PVA-alginate was the most effective and was used for reduction of Cr(VI) in a bioreactor. Cr(6+) reduction efficiency decreased as Cr(6+) was increased from 2 to 12 mg l(-1) but increased with an increase in biomass concentration. However, increasing the flow rate from 2 to 8 ml h(-1) did not significantly affect Cr(6+) reduction. The reduction was faster in simulated effluent than in synthetic medium and complete removal of 8 mg Cr(6+) l(-1) from effluent and synthetic medium occurred in 2 and 12 h, respectively. Our results indicate that immobilized S. griseus cells could be applied for the large-scale bioremediation of chromate-containing effluents and wastewaters.</p>10aBioremediation10aChromate reduction10aImmobilized cells10aPolyvinyl alcohol-alginate10aStreptomyces griseus1 aPoopal, Ashwini, C.1 aLaxman, Ryali, Seeta  uhttps://library.ncl.res.in/content/chromate-reduction-pva-alginate-immobilized-streptomyces-griseus-bioreactor-001925nas a2200205   4500008004100000022001400041245007200055210006900127260007300196300001200269490000800281520119200289653001701481653002301498653002401521653002501545100002401570700002501594856010001619       2009                        eng d  a0304-389400aStudies on biological reduction of chromate by Streptomyces griseus0 aStudies on biological reduction of chromate by Streptomyces gris  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcSEP  a539-5450 v1693 a<p>Chromium is a toxic heavy metal used in various industries and leads to environmental pollution due to improper handling. The most toxic form of chromium Cr(VI) can be converted to less toxic Cr(III) by reduction. Among the actinomycetes tested for chromate reduction, thirteen strains reduced Cr(VI) to Cr(III), of which one strain of Streptomyces griseus (NCIM 2020) was most efficient showing complete reduction within 24h. The organism was able to use a number of carbon sources as electron donors. Sulphate, nitrate, chloride and carbonate had no effect on chromate reduction during growth while cations such as Cd, Ni, Co and Cu were inhibitory to varying degrees. Chromate reduction was associated with the bacterial cells and sonication was the best method of cell breakage to release the enzyme. The enzyme was constitutive and did not require presence of chromate during growth for expression of activity. Chromate reduction with cell free extract (CFE) was observed without added NADH. However, addition of NAD(P)H resulted in 2-3-fold increase in activity. Chromate reductase showed optimum activity at 28 degrees C and pH 7 (C) 2009 Elsevier B.V. All rights reserved.</p>10aBioreduction10aChromate reductase10aHexavalent chromium10aStreptomyces griseus1 aPoopal, Ashwini, C.1 aLaxman, Ryali, Seeta  uhttps://library.ncl.res.in/content/studies-biological-reduction-chromate-streptomyces-griseus-0