Keum Shin

Symbiotic adaptation of bacteria in the gut of Reticulitermes speratus: Low endo-β-1,4-glucanase activity

The termite is a good model of symbiosis between microbes and hosts and possesses an effective cellulose digestive system. Oxygen-tolerant bacteria, such as Dyella sp., Chryseobacterium sp., and Bacillus sp., were isolated from Reticulitermes speratus gut. Notably, the endo-beta-1,4-glucanase (EG) activity of all 16 strains of isolated bacteria was low. Due to the combined activity of EG from the termites and their symbiotic protozoa, the bacteria might not be compelled to express EG. This observation demonstrates how well intestinal bacteria have assimilated themselves into the efficient cellulose digestive systems of termites.

Characterization of Cellulases from Schizophyllum commune for Hydrolysis of Cellulosic Biomass

The optimum culture condition of Schizophyllum commune for the cellulase production and its enzymatic characteristics for saccharification of cellulosic biomass were analyzed. S. commune secrets -1,4-xylosidase (BXL) and cellulases, including endo--1,4-glucanase (EG), cellobiohydrolase (CBH), and -glucosidase (BGL). The optimum reaction temperature for all cellulases was and the thermostable range was C. The optimum reaction pH for all cellulases was 5.5 in a range of temperature from to . The best nutritions for the cellulase production of S. commune among tested nutrients were 2% cellulose for the carbon source and corn steep liquor or peptone/yeast extract for the nitrogen source without vitamins. The environmental culture condition for the cellulase production was 5.5~6.0 for pH at . The enzyme activities of EG, BGL, CBH, and BXL were 3670.5, 631.9, 398.5, and 15.2 U/, respectively, after concentration forty times from the culture broth of S. commune which was grown at the optimized culture condition. Alternative filter paper unit assay showed 11 FPU/ enzyme activity. The saccharification tests using cellulase of S. commune showed the low saccharification rate on tested hardwoods but a high value of 50.5% on cellulose, respectively. The saccharification rate (50.5%) of cellulose by cellulase produced in this work is higher than 45.7% in the commercial enzyme (Celluclast 1.5L, 30 FPU/g, glucan).

A New α-Amylase from Reticulitermes speratus KMT1

ABSTRACT Termites are wood pests that cause vast economic damage every year. They digest both cellulose and starch, but the enzymes for starch digestion have not been well characterized. We obtained complete amino acid sequence information on the KME1 α-amylase from Reticulitermes speratus KMT1 through analysis of total mRNA sequences. The KME1enzyme has two α-amylase domains and is 68% identical to the α-amylase from Blattellager manica, its closest rela-tive in the GenBank database. Some unique features of its conserved region and its distant evolutionary relationship toother insect α-amylases suggest that KME1 is a new type of α-amylase.Keywords : Termite, Reticulitermes speratus KMT1, α-amylase, Homologous search, Phylogenetic analysis 1. INTRODUCTION 1) Termites efficiently degrade woody cellulose through a symbiotic collaboration with gut mi-croorganisms, and they absorb the degradation products as nutrients (Nakashima et al., 2002; Watanabe et al., 1997; Zhou et al., 2007). In the first step of cellulose degradation, termites secrete an endo-β-1,4-glucanase from their sali-vary glands that enzymatically reduces the size of cellulose. Later, symbiotic microorganisms in the termite gut secrete cellobiohydrolase and β-glucosidase to convert cellulose into glucose (Cho et al., 2010; Nakashima et al., 2002). Since starch is an energy-storing material in biological systems, termites should be able to use it as food. It has been shown that Coptotermes for-mosanus can survive on starch or glucose as a sole nutrient as well as on cellulose, and it does this without the assistance of symbiotic protozoans (Kanai et al., 2008). However, only the sequence of a partial catalytic domain of the amylase gene from Coptotermes formosanus has so far been reported (GenBank Accession number: KC740998); no complete sequence is available. Amylases are classified into three groups, α- amylase (EC 3.2.1.1), β-amylase (EC 3.2.1.2), and γ-amylase (EC 3.2.1.3), depending on where they cleave the α(1 → 4) glucosidic linkage on

Effect of Carbon Source on the Hydrolytic Ability of the Enzyme from Fomitopsis pinicola for Lignocellulosic Biomass

In this study, effect of carbon source on the hydrolytic ability of the enzyme from Fomitopsis pinicola, a brown rot fungi, for lignocellulosic biomass were examined on two lignocellulosic biomasses (rice straw and wood) without any pretreatment. Cellulase activities of crude enzyme from F. pinicola, which was cultured on softwood mixture as a carbon source, were 19.10 U/ for endo--1,4-gulcanase (EG), 36.1 U/ for -glucosidase (BGL), 7.27 U/ for cellobiohydrolase (CBH), and 7.12 U/ for -1,4 xylosidase (BXL). Softwood mixture as a carbon source in F. pinicola comparatively enhanced cellulase activities than rice straw. The optimal pH and temperature of the cellulase was identified to pH 5 and for the hydrolysis of rice straw. Under these condition rice straw was hydrolyzed to glucose by the cellulase up to based on the glucan amount of the rice straw for 72 h, while the hydrolytic capability of commercial enzyme (Celluclast 1.5) from rice straw to glucose was estimated to at the same experimental condition. In case of addition of Tween 20 (0.1% w/w, substrate) to the cellulase the hydrolysis of rice straw to glucose was enhanced to .

Enzymatic Hydrolysis of Rice Straw, a Lignocellulosic Biomass, by Extracellular Enzymes from Fomitopsis palustris

ABSTRACT In the enzymatic hydrolysis of rice straw and wood meals using extra-cellular enzymes from Fomitopsis palustris, key factors which enhanced the sugar conversion yield were investigated in this work, such as enzyme production and enzyme reaction conditions, surfactant effects, and the surface structure of substrates. F. palustris cultured with softwood mixture produced 12.0 U/ ㎖ for endo-β-1,4-gulcanase (EG), 116.68 U/ ㎖ for β-glucosidase (BGL), 18.82 U/ ㎖ for cello- biohydrolase (CBH), and 13.33 U/ ㎖ for β-xylosidase (BXL). These levels of BGL, CBH, and BXL activities were two to four folds more than enzyme activities of F. palustris cultured with rice straw. The optimum reaction conditions of cellulase-RS which produced by F. palustris with rice straw and cellulase-SW which produced by F. palustris with softwood mixture were pH 5.0 at 45°C and pH 5.0 at 50°C, respectively. The sugar conversion yield of cellulase-SW had the highest value of 40.6 ± 0.6% within 72 h when rice straw was used as substrate. By adding 0.1% Tween 20 (w/w-substrate), the sugar conversion yield of rice straw was increased to 44%, which was about four fifths sugar conversion yield of commercial enzyme, Celluclast 1.5L (Novozyme A/S). A low crystallinity and an intensive fibril surface observed by the scanning electron microscope may explain the high sugar conversion yield of rice straw. Keywords : enzymatic hydrolysis, Formitopsis palustris, cellulase, rice straw, carbon source

Cellulose Hydrolysis by Digestive Enzymes of Reticulitermes speratus, a Native Termite from Korea

This study was to investigate the enzymatic hydrolysis of cellulose using the cellulase from whole body of the native termite collected in Milyang-si, Kyungsangnamdo, Korea. In the results, optimal temperature and pH for the enzyme of native termites were and pH 5.5 for both endo--1, 4-glucanase and -glucosidase. Enzyme activity of the termite enzyme was shown . And the highest glucose hydrolysis rate of cellulose by the digestive enzyme from test termites was 24.5% based on the glucan, comparing 59.7% by commercial enzyme (only celluclast 1.5 L) at 1% (w/v) substrate and 36 hours in hydrolysis time. This hydrolysis rate by the digestive enzyme from test termites was comparatively high value in 41% level of the commercial enzyme. When cellulose was hydrolyzed by the digestive enzyme of the native termite, glucose hydrolysis was almost completed in 12 hours which was the considerably reduced time for cellulose hydrolysis. It was suggested that the quiet short reaction time for cellulose hydrolysis by the enzyme from native termite could be a very high advantage for development of hydrolysis cellulase for lignocellulosic biomass.

Cellulase Production in the Digestive Organs of Reticulitermes speratus, a Native Termite from Milyang, Korea

This study investigated on enzyme production in the digestive organs of the native termite (Reticulitermes speratus) in Milyang, Korea. Four types of major cellulases [EG (endo-1,4--glucanase), BGL (-glucosidase), CBH (cellobiohydrolase) and BXL (-1,4-xylosidase)] were present in the digestive organs of the termite. The strong enzyme activity for BGL was found from the native termite, and also shown that the enzyme was distributed in the salivary gland, foregut, and hindgut. BXL, which breaks down hemicellulose near the amorphous region, was detected mainly from salivary gland, foregut, and midgut. However, CBH was distributed mainly in the hindgut. Meanwhile, EG which degrades cellulose, was found mainly in the hindgut and salivary glands. These facts indicate that celluases production patterns are differ from different sites compare to the same species found in Japan, suggesting that enzyme production in the digestive organs of termites is changed according to their habitats.

Immobilization of cellulases from Fomitopsis pinicola and their changes of enzymatic characteristics.

Cellulase from Formiptosis pinicola KMJ812 is an efficient cellulose degradation enzyme complex, especially with a high -glucosidase activity. In this study, the change in enzymatic characteristics by immobilization and the reduction of immobilized enzyme activity by repeated usages were evaluated using cellulases from F. pinicola KMJ812. Among tested four resins, Duolite A568 resin had the best enzyme activity yield with 61.7% cellulase activity and 64.4% - glucosidase activity during the cellulase immobilization. The best reaction temperature was for both cellulase and -glucosidase activities which were higher than the unimmobilized soluble cellulases. The best reaction pH was 4.0 for cellulase activity which was a little more basic than a soluble form and 4.5 for -glucosidase activity. The immobilized cellulase activity was remained 98% of the beginning activity after 72 h incubation at and 50% of the beginning activity after eight times usage at .