Malaysian Applied Biology Journal

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49_02_05

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Malays. Appl. Biol. (2020) 49(2): 27–35

 

EFFECT OF CALCIUM IONS TO THE ACTIVITY AND STABILITY

OF EXTRACELLULAR LIPASE PRODUCED BY MODERATE

HALOPHILIC BACTERIA Halomonas meridiana BK-AB4


GALO AYU MEGGA NANDA and RUKMAN HERTADI*


Department of Chemistry, Faculty of Mathematics and Natural Sciences

Institut Teknologi Bandung, Jl. Ganesha 10, Bandung 40132, Indonesia

*E-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it


Accepted 27 April 2020, Published online 6 July 2020


ABSTRACT

This study reported the isolation and biochemical studies of extracellular lipase produced by a moderate halophilic bacterium, Halomonas meridiana BK-AB4. The estimated molecular weight of the lipase BK-AB4 is about 50 kDa. The study of metal ions effect to the enzyme activity revealed the strong dependency towards the presence of Ca2+ ion. Further studies showed that the optimum pH of the enzyme was similar in the presence and the absence of Ca2+ ions. However, the presence of Ca2+ ions could improve the enzyme thermal stability as indicated by the shift of its optimum temperature from 45°C - 50°C. The addition of Ca2+ ions was also enhancing residual activity towards various inhibitors, such as SDS and PMSF up to 55% and 68%, respectively. Another interesting effect of the addition of Ca2+ ions were noted when various organic solvents were added to the enzyme solution in the ratio of 1:1. The activity of the enzyme increased up to 122% and 126% relative to the control when methanol and n-butanol were added, respectively. This study thus showed that the addition of Ca2+ ion not only improved the catalytic activity of lipase BK-AB4 but also made the enzyme more tolerable against various perturbations.


Key words: Extracellular lipase, halophilic bacteria, Halomonas meridiana BK-AB4, metal ions activator

 

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