Nitrile degradation by free and immobilized cells of the thermophile Bacillus sp. UG-5B, isolated from polluted industrial waters

Abstract

A moderately thermophilic Gram-positive, sporulating, rod-shaped strain of Bacillus with nitriledegrading activity was isolated from polluted industrial waters. Whole cells and cell-free extracts from the end of exponential growth phase expressed 7.6 nkat mg -1 and 2.0 nkat mg -1 benzonitrile-degrading activity, respectively, after cultivation in a fermentor with complex medium containing benzonitrile as an inducer. The benzonitrile degradation took place via the nitrilase pathway directly to benzoic acid without intermediate formation of benzamide. Samples with benzonitrilase activity of 7.6 nkat mg -1 converted 3 mg benzonitrile in 1 h at 45°C. The half-life of benzonitrilase activity for a whole cell suspension and for cells immobilized in 2% agar was 4.5 min and 6 min at 70°C without substrate and 3 min at 90°C with substrate, respectively. The nitrilase had a broad substrate spectrum. The active biocatalyst obtained by immobilization was used in a continuous process and total biodegradation of 14.1 mM benzonitrile and 37.2 mM 4-cyanopyridine in a column bioreactor at 50°C for 5 h was achieved.

Cultivation and Genomic Analysis of “Candidatus Nitrosocaldus islandicus,” an Obligately Thermophilic, Ammonia-Oxidizing Thaumarchaeon from a Hot Spring Biofilm in Graendalur Valley, Iceland

“…Both substrates are relatively thermostable ( Isidorov et al, 1992 ; Miyakawa et al, 2002 ). Nitriles occur as intermediates of microbial metabolism ( Kobayashi et al, 1993 ) and nitrile hydratases have previously been isolated from several thermophiles ( Cramp et al, 1997 ; Almatawah et al, 1999 ; Kabaivanova et al, 2008 ). Furthermore, both compounds are intermediates of the proposed abiotic synthesis of organics at hydrothermal sites ( Miller and Urey, 1959 ; Schulte and Shock, 1995 ) and could thus be available in the hot spring habitat of “ Ca.…”

Biosynthesis of Iminodiacetic Acid from Iminodiacetonitrile by Immobilized Recombinant <i>Escherichia coli</i> Harboring Nitrilase

“…The reason behind the decreased activity is that the preparation of carrageenan gel required a high temperature, which could cause damage to E. coli . This indicates that carrageenan and agar are more suitable for thermophilic strain [Kabaivanova et al, 2008]. When SA gel was used as matrix ( fig.…”

Biodegradation of 2,2' 4,4-tetrabromodiphenyl Ether in an Aerobic Environment by a Novel Strain of <i>Bacillus sp.</i>

“…About degradation function Bacillus sp., most come from the polluted soil [11,12] , and some came from sediment [13] and water pollution [14] . Bacillus species are attractive industrial organisms not only because of their high growth rates leading to short fermentation cycle times, but also the spore-forming can resist many adverse environments.…”