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Papers by K. Kruus

Journal of Applied Microbiology, 2004

Applied Microbiology and Biotechnology, 1995

CelS is the most abundant subunit and an exoglucanase component of the Clostridium thermocellum c... more CelS is the most abundant subunit and an exoglucanase component of the Clostridium thermocellum cellulosome, multicomponent cellulase complex. The product inhibition pattern of CelS was examined using purified recombinant CelS (rCelS) produced in Escherichia coli. The rCelS activity on cellopentaose was strongly inhibited by cellobiose. The rCelS activity was also inhibited by lactose. Glucose was only marginally inhibitory. Cellobiose appeared to inhibit the rCelS activity through a competitive mechanism. The inhibition was relieved when beta-glucosidase was added, presumably because of the conversion of cellobiose into glucose. These hydrolysis product inhibition patterns are consistent with those of the crude enzyme (cellulosome), suggesting that CelS is a rate-limiting factor in the activity of the cellulosome.

ACS Symposium Series, 2003

ABSTRACT Since the successful introduction of commercial hydrolytic enzymes to lignocellulose pro... more ABSTRACT Since the successful introduction of commercial hydrolytic enzymes to lignocellulose processing, the next generation of oxidative enzymes are now entering the markets. Significant progress in molecular biology have enabled us to better understand the electron transfer mechanisms in the lignocellulosic substrates and improve the production of these enzymes at a commercial scale. The most intensively studied application is enzyme catalysed delignification, for which several concepts have been introduced. Recently, other applications, such as oxidative fibre modification or activation of lignin to replace traditional adhesives have been actively studied. However, in spite of extensive research, the underlying mechanisms are still only partially understood. This paper reviews recent advances in the application of oxidative enzymes for lignocellulose processing.

Process Biochemistry, 2012

Journal of Applied Microbiology, 2005

International Dairy Journal, 2009

Chemical Engineering Journal, 2013

ABSTRACT Linoleic acid was converted into hydroperoxides by a Gaeumannomyces graminis tritici lip... more ABSTRACT Linoleic acid was converted into hydroperoxides by a Gaeumannomyces graminis tritici lipoxygenase produced recombinantly in Trichoderma reesei. Hydroperoxide production was optimized using a face-centred experimental design in order to study the effects of pH, temperature and time on the conversion of linoleic acid into four regioisomeric hydroperoxyoctadecadienoic acids (HPODE): 13-(Z,E)-, 9-(E,Z)-, 13-(E,E)-, 9-(E,E)-HPODE. Fitting equations described satisfactorily the system behavior and showed that reaction time was the most inﬂuencing independent variable. A set of independent variables (pH = 6.7, temperature = 23.9 ºC and time = 18 h) allowed to obtain high yields of hydroperoxides (88.0%) with a good selectivity for the 13-(Z,E)-HPODE isomer (47.4%) when the initial substrate concentration was 10 g/L. The production was further investigated using industrially relevant linoleic acid concentrations (100–300 g/L) leading to HPODE yields of 40% and the volumetric productivity 3.6 g/(L h), and a selectivity for 13-(Z,E)-HPODE of around 74%.

Applied Microbiology and Biotechnology, 2011

Enzyme and Microbial Technology, 2004