Production of extracellular laccase from the newly isolated Bacillus sp. PK4

Abstract

Laccase belongs to the family of multicopper oxidase and have wide range of biotechnological applications starting from the food industry to bioremediation. However, the use of laccase at commercial scale is hindered by factors like high enzyme cost, low activity and /or stability under given conditions. This study was carried out with aim of screening for extracellular thermostable laccase producing bacteria. Twenty-two (22) laccase positive strains were isolated from the selected environmental samples while extracellular laccase activity was detected only in six strains namely TM1, TMT1, PK4, PS1, TMS1 and ASP3. The laccase enzyme produced from PK4 was found to be more thermostable with a half-life of 60 min at 80°C. The strain PK4 was identified and designated as Bacillus sp. PK4. The laccase production was optimized using one-factor-at-a-time method and maximum enzyme production were observed at the temperature of 37°C, pH 7.5, 10% inoculum size with yeast extract and glucose as the nitrogen and carbon sources, respectively at an agitation rate of 150 rpm. Copper sulphate at 0.1 mM concentration was found to maximize the laccase production among the tested inducers. Among the trace elements, FeSO 4 and ZnSO 4 gave the maximum laccase production for the isolated strain in comparison with the control. The effect of copper-induced time showed that the addition of copper before inoculation effectively increased the laccase production compared to the addition of copper after 2, 4, 6 and 8 h of inoculation. The optimization of the media resulted in 11.8 fold increase in laccase production.

Studies on Lignin Degradation Activity by Pseudomonas aeruginosa Isolated from Kware Lake

“…As pH increase to 7.0, 7.5 and rising toward alkalinity there was gradual increase of lignin degradation and biomass production. This is similar with the finding of Murugesan and Vembu [18] who reported that Bacillus sp. produced high laccase activity at pH 7.5 and gradually decrease from 7.5 to 10.0.…”

“…The effect of growth parameters were determined as in one factor one time method as described by Murugesan and Vembu [18] A twenty four (48) hours old culture of Pseudomonas aeruginosa was inoculated into 50 ml of mineral salt medium (MSA) incorporated with 5% lignin extract from plant. The growth conditions such as incubation time, temperature, pH and agitation whose show highest activity were chosen and used in this study.…”

“…Degradation rate Biomass at higher agitation rate the enzyme structure might be changed [18]. However, at lower agitation rate there was both reduction of both degradation and growth of Pseudomonas aeruginosa, this indicated that mixing of growth media and supply of oxygen was insufficient.…”

Tree bark scrape fungus: A potential source of laccase for application in bioremediation of non-textile dyes

“…Optimization of variables for growth and production of laccase. The physical parameters, for example,pH (2-10), temperature (20-55˚C), incubation time (1-12 d) [24], and nutrients, such as carbon sources (1.5%),which included glucose, sucrose, starch, maltose, lactose, fructose, and glycerol, organic nitrogen sources (1.5%), such as L-asparagine, glutamic acid, glycine, L-proline, yeast extract, peptone, urea, inorganic nitrogen sources (1.5%),which includedammonium nitrate, sodium nitrate, potassium nitrate, ammonium chloride, ammonium dihydrogen phosphate, and ammonium sulfate, inducers (10-50 μM), namely CuSO 4 , tween 80, veratryl alcohol, guaiacol, 2,5 xylidine, vanillic acid, gallic acid, ammonium tartrate, and vanillin were optimized forthemaximumproduction of laccase [30].…”

Tree bark scrape fungus: A potential source of laccase for application in bioremediation of non-textile dyes

“…The physical parameters viz. pH (2)(3)(4)(5)(6)(7)(8)(9)(10), temperature (20- were optimized for optimum production of laccase [30].…”