Production of cellulases and xylanases under catabolic repression conditions from mutant PR-22 of Cellulomonas flavigena

Oscar A. Rojas-Rejón, Héctor M. Poggi-Varaldo, Ana C. Ramos-Valdivia, Alfredo Martínez-Jiménez, Eliseo Cristiani-Urbina, Mayra De La Torre Martínez, Teresa Ponce-Noyola

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18 Scopus citations

Abstract

Derepressed mutant PR-22 was obtained by N-methyl-N′-nitro-N- nitrosoguanidine (MNNG) mutagenic treatment of Cellulomonas flavigena PN-120. This mutant improved its xylanolytic activity from 26.9 to 40 U mg-1 and cellulolytic activity from 1.9 to 4 U mg-1; this represented rates almost 2 and 1.5 times higher, respectively, compared to its parent strain growing in sugarcane bagasse. Either glucose or cellobiose was added to cultures of C. flavigena PN-120 and mutant PR-22 induced with sugarcane bagasse in batch culture. The inhibitory effect of glucose on xylanase activity was more noticeable for parent strain PN-120 than for mutant PR-22. When 20 mM glucose was added, the xylanolytic activity decreased 41% compared to the culture grown without glucose in mutant PR-22, whereas in the PN-120 strain the xylanolytic activity decreased by 49% at the same conditions compared to its own control. Addition of 10 and 15 mM of glucose did not adversely affect CMCase activity in PR-22, but glucose at 20 mM inhibited the enzymatic activity by 28%. The CMCase activity of the PN-120 strain was more sensitive to glucose than PR-22, with a reduction of CMCase activity in the range of 20-32%. Cellobiose had a more significant effect on xylanase and CMCase activities than glucose did in the mutant PR-22 and parent strain. Nevertheless, the activities under both conditions were always higher in the mutant PR-22 than in the PN-120 strain. Enzymatic saccharification experiments showed that it is possible to accumulate up to 10 g l-1 of total soluble sugars from pretreated sugarcane bagasse with the concentrated enzymatic crude extract from mutant PR-22.

Original languageEnglish
Pages (from-to)257-264
Number of pages8
JournalJournal of Industrial Microbiology and Biotechnology
Volume38
Issue number1
DOIs
StatePublished - Jan 2011

Keywords

  • Cellulase
  • Cellulomonas flavigena
  • Derepressed
  • Mutant
  • Saccharification
  • Sugarcane bagasse
  • Xylanase

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