Optimization of As Bioleaching by Herbaspirillum sp. GW103 Coupled with Coconut Oil Cake

摘要: ABSTRACT The objective of this study was to optimize the experimental conditions for bioleaching arsenic (As) usingHerbaspirillum sp. GW103 and understand interaction between bacteria As during bioleaching. Five variables,temperature, time, CaCO 3 , coconut oil cake, shaking rate, were optimized using response surface methodology (RSM)based Box-Behnken design (BBD). Maximum (73.2%) observed at 30oC, 60 h incubation, 1.75%CaCO 3% 140 rpm. Sequential extraction bioleached soil revealed that isolateHerbaspirillum significantly reduced 28.6% water soluble fraction increased 38.8% carbonatefraction. results indicate diazotrophic Herbaspirillum could be used bioleachingAs from mine soil.Key words : Arsenic, Bioleaching, design, sp., Heavy metals 1. Introduction metal pollution has become a global environmen-tal problem, with industrial activities mining met-allurgical being major contributors. SouthKorea long history activities, whichhas widespread in last two decades (Govartha-nan et al., 2013). Currently, most depleted metalmines have been abandoned left unmanaged, resultingin contamination nearby agricultural aquaticenvironment. To address concern, conventional physi-cal chemical methods explored, but low effi-ciency high costs limit use these (Yanget 2008). Hence, biological such as bioremediation, whichuses microorganisms plants remediation con-taminated water, are sought after because theirsimple, inexpensive, eco-friendly nature (Govarthananet 2014a, c). Bioleaching is type bioremediationthat widely removal heavy metalsfrom sludge, sediments, ores, tailings, contami-nated (Bosecker, 2001).Microorganisms solubilize solid substrateseither directly or indirectly by producing organic acids andenzymes (Rulkens 1995). Several bacterial isolatesbelonging genera Acidothiobacillus, Acetobacter, Aci-dophilum, Arthrobacter, Pseudomonas, Bacillus havebeen reported efficient bioleachers (Mulligan Cloutier,2003; Deng 2012; Chiang This an extension our previous thatreported Cu efficiency diazotrophicbacteria isolated soil(Govarthanan 2014a); here we focus on isolate’sarsenic potential. It establishedthat depends geochemistryand activity. limited nutrient availability inmine reduces growth sev-eral inorganic supplements