Isolation and characterization of a molybdenum-reducing and SDSdegrading Klebsiella oxytoca strain Aft-7 and its bioremediation application in the environment

Abstract

Pollution as a result of anthropogenic activities is a severe global issue. These activities including inappropriate disposal, industrial and prospecting activities and unnecessary use of agricultural chemicals have triggered international initiatives to eliminate these contaminants. In this work we screen the ability of a molybdenum-reducing bacterium isolated from contaminated soil to grow and reduce molybdenum on various detergents. The bacterium was able to grow on SDS as a carbon source although the compound did not support molybdenum reduction. The bacterium reduces molybdate to Mo-blue optimally between pH 5.8 and 6.3 and between 25 and 34 o C. Glucose was the best electron donor for supporting molybdate reduction followed by sucrose, D-mannitol, D-sorbitol, lactose, salicin, trehalose, maltose and myo-Inositol in descending order. Other requirements include a phosphate concentration between 5.0 and 7.5 mM and a molybdate concentration between 5 and 20 mM. The absorption spectrum of the Mo-blue produced was similar to previous Mo-reducing bacterium, and closely resembles a reduced phosphomolybdate. Molybdenum reduction was inhibited by mercury (ii), silver (i) and copper (ii) at 2 ppm by 62.1, 33.9 and 33.6%, respectively. Biochemical analysis resulted in a tentative identification of the bacterium as Klebsiella oxytoca strain Aft-7. The ability of this bacterium to detoxify molybdenum and degrade detergent makes this bacterium an important tool for bioremediation.

Isolation and Characterisation of a Molybdenum-reducing and Metanil Yellow Dye-decolourising Bacillus sp. strain Neni-10 in Soils from West Sumatera, Indonesia

“…An aliquot of the soil suspension (0.1 mL) was then spread onto an agar of the following media (pH 6.5) and incubated at room temperature. The composition (w/v) of the media is as follows: yeast extract (0.5%), MgSO 4 •7H 2 O (0.05%), Na 2 MoO 4 •2H 2 O (0.242% or 10 mM), glucose (1%), (NH 4 ) 2 •SO 4 (0.3%), NaCl (0.5%), agar (1.5%), and Na 2 HPO 4 (0.071% or 5 mM) (Masdor et al 2015). After 48 hours of incubation, several white and five blue colonies appeared.…”

“…The first process is catalysed by bacterial genera, such as Desulfovibrio and Desulfotomaculum, which required complete anaerobicity. On the other hand, the second process is catalysed by numerous heterotrophic bacteria from various genera (Shukor et al 2007;Shukor et al 2008a;Rahman et al 2009;Shukor et al 2009a;Yunus et al 2009;Shukor et al 2009b;Shukor et al 2010a;Shukor et al 2010b;Lim et al 2012;Ahmad et al 2013a;Halmi et al 2013;Ibrahim et al 2015;Masdor et al 2015;Nuraini et al 2015). The second process is a more feasible tool as the conversion occurs under facultative anaerobic conditions, and no toxic gas is produced (Ghani et al 1993).…”

“…The search for multiple detoxification microorganisms is on the rise globally (Ahmad et al 2013b;Agrawal et al 2014;Ahmad et al 2014;Muhamad et al 2015). Examples include the heavy metal chromate reduction coupled to azo dye decolourization (Chaudhari et al 2013) and the isolation of Mo-reducing bacteria showing sodium dodecyl sulfate (SDS)-degrading Masdor et al 2015), phenol-degrading (Ibrahim et al 2015) and glyphosatedegrading (Sabullah et al 2016) properties.…”

ISOLATION AND CHARACTERIZATION OF A MOLYBDENUM-REDUCING AND GLYPHOSATE-DEGRADING Klebsiella oxytoca STRAIN SAW-5 IN SOILS FROM SARAWAK

“…Additionally, the toxicity of molybdenum to such as sheep and cows at levels of several parts per million has been reported (Kincaid, 1980). The removal of molybdenum through bioremediation especially bioreduction is potentially the most economical approach in the long term (Lim et al, 2014), and several molybdenum-reducing bacteria have been reported (Shukor and Syed, 2010;Ahmad et al, 2013;Masdor et al, 2015). Heavy metals reduction coupled with xenobiotic degradation has been reported (Chirwa and Wang, 2000;Chung et al, 2007).…”

“…Heavy metals reduction coupled with xenobiotic degradation has been reported (Chirwa and Wang, 2000;Chung et al, 2007). For example, two molybdenum-reducing bacteria with the ability to utilize sodium dodecyl sulfate (SDS) as the sole carbon have been isolated Masdor et al, 2015). The use of foreign microbes for bioremediation could cause ecological problems, and thus is not recommended (Walter et al, 2003).…”