Medium factors affecting extracellular protease activity by Bacillus sp. HTS 102—A novel wild strain isolated from Portuguese merino wool

Ana Catarina Queiroga, Manuela Estevez Pintado, Francisco Xavier Malcata*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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Abstract

The synthesis of an extracellular protease by Bacillus sp. HTS102—a wild strain recently isolated from the wool of Portuguese Merino ewes, was optimized. This protease is thermostable and particularly resistant to harsh environmental conditions—and appears to bear a unique ability to hydrolyze keratin-rich solid materials. Following a preliminary screening for the most relevant medium factors involved in processing, a fractional factorial design (2VI 6-1) was applied to ascertain the effects of six relevant parameters— viz. yeast extract concentration, peptone level, inoculum size, stirring rate, temperature and pH. The concentrations of yeast extract and peptone, as well as the incubation temperature and pH were found to play significant roles; and the 2-factor interaction between yeast extract level and pH was also significant. A 2.2-fold increase in the overall level of protease synthesis was eventually attained, with the improved medium relative to the basal medium—which is noteworthy when compared with competing proteases and previous optimization efforts.
Original languageEnglish
Article number33204
Pages (from-to)44-53
Number of pages10
JournalNatural Science
Volume5
Issue number6A
DOIs
Publication statusPublished - Jun 2013

Keywords

  • Fractional Factorial Design
  • Thermotolerant Enzyme
  • Proteolytic Activity
  • Bacillus sp.
  • Ewe’s Wool

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