• Journal of Microbiology and Biotechnology
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• 제31권8호
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• pp.1123-1133
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• 2021

Biodegradation is the key process involved in natural lignocellulose biotransformation and utilization. Microbial consortia represent promising candidates for applications in lignocellulose conversion strategies for biofuel production; however, cooperation among the enzymes and the labor division of microbes in the microbial consortia remains unclear. In this study, metagenomic analysis was performed to reveal the community structure and extremozyme systems of a lignocellulolytic microbial consortium, TMC7. The taxonomic affiliation of TMC7 metagenome included members of the genera Ruminiclostridium (42.85%), Thermoanaerobacterium (18.41%), Geobacillus (10.44%), unclassified_f__Bacillaceae (7.48%), Aeribacillus (2.65%), Symbiobacterium (2.47%), Desulfotomaculum (2.33%), Caldibacillus (1.56%), Clostridium (1.26%), and others (10.55%). The carbohydrate-active enzyme annotation revealed that TMC7 encoded a broad array of enzymes responsible for cellulose and hemicellulose degradation. Ten glycoside hydrolases (GHs) endoglucanase, 4 GHs exoglucanase, and 6 GHs β-glucosidase were identified for cellulose degradation; 6 GHs endo-β-1,4-xylanase, 9 GHs β-xylosidase, and 3 GHs β-mannanase were identified for degradation of the hemicellulose main chain; 6 GHs arabinofuranosidase, 2 GHs α-mannosidase, 11 GHs galactosidase, 3 GHs α-rhamnosidase, and 4 GHs α-fucosidase were identified as xylan debranching enzymes. Furthermore, by introducing a factor named as the contribution coefficient, we found that Ruminiclostridium and Thermoanaerobacterium may be the dominant contributors, whereas Symbiobacterium and Desulfotomaculum may serve as "sugar cheaters" in lignocellulose degradation by TMC7. Our findings provide mechanistic profiles of an array of enzymes that degrade complex lignocellulosic biomass in the microbial consortium TMC7 and provide a promising approach for studying the potential contribution of microbes in microbial consortia.

• Journal of Microbiology and Biotechnology
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• 제22권2호
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• pp.239-243
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• 2012

Degradation of butylbenzyl phthalate (BBP) by the white rot fungus Pleurotus ostreatus and the activities of some degrading enzymes were examined in two different media containing 100 mg/l of the compound. P. ostreatus pre-grown for 7 days in complex YMG medium was able to completely degrade BBP within an additional 24 h but degraded only 35 mg/l of BBP in 5 days of incubation in minimal medium. Fungal cell mass in the culture in YMG medium was higher in the presence than in the absence of BBP. The esterase activity of the fungal culture in YMG medium was higher than that in minimal medium and increased with the addition of BBP. On the contrary, laccase activity was higher in minimal medium and it did not increase upon the addition of BBP. General peroxidase activity increased for a few days after the addition of BBP to both media. The degradation of BBP and its metabolites by P. ostreatus thus may be attributed mostly to esterase rather than lignin-degrading laccase. In addition, the activities of the enzymes involved in BBP degradation and their changes varied significantly in the different media and culture conditions.

• KSBB Journal
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• 제32권2호
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• pp.96-102
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• 2017

The lignocellulose that is a major component of spent coffee ground was degraded and saccharified. To implement the spent coffee, after several pre-treatments, inoculation of Phanerochaete chrysosporium and solid-state fermentation were conducted. The optimal temperature of the enzymes (lignin peroxidase, manganese peroxidase, xylanase, laccase, and cellulase) for degradation of lignocellulose by P. chrysosporium was found. We also measured the maximum activity of enzymes (lignin peroxidase 0.15 IU/mL, manganese peroxidase 0.90 IU/mL, laccase 0.11 IU/mL, cellulase 5.87 IU/mL, carboxymethyl cellulase 9.52 IU/mL, xylanase 1.16 IU/mL) used for the process. As a result, 4.73 mg/mL of reduced sugar was obtained and 61.02% of lignin was degraded by solid state fermentation of P. chrysosporium on spent coffee ground.

• Molecules and Cells
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• 제38권5호
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• pp.390-395
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• 2015

Degradation of chlorophyll (Chl) by Chl catabolic enzymes (CCEs) causes the loss of green color that typically occurs during senescence of leaves. In addition to CCEs, STAYGREEN1 (SGR1) functions as a key regulator of Chl degradation. Although sgr1 mutants in many plant species exhibit a staygreen phenotype, the biochemical function of the SGR1 protein remains elusive. Many recent studies have examined the physiological and molecular roles of SGR1 and its homologs (SGR2 and SGR-LIKE) in Chl metabolism, finding that these proteins have different roles in different species. In this review, we summarize the recent studies on SGR and discuss the most likely functions of SGR homologs.

• Asian-Australasian Journal of Animal Sciences
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• 제16권3호
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• pp.389-393
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• 2003

Present study investigate the effect of enzyme supplementation, methods (applied to rumen or enzyme treated diet) compared with no enzyme diet, on rumen fermentation and apparent nutrient digestibility in a $3{\times}3$ Latin square design with three rumen cannulated Korean Native goats. In situ rumen degradation kinetics was studied in three rumen cannulated Holstein steers. Three diets were, no enzyme, 1% enzyme in rumen and 1% enzyme in diet. The enzyme was sprayed onto forage, and the forage: concentrate ratio was 30:70. Degradation kinetics was studied with three enzyme levels (0, 1 and 2%, w/w) and four pre-treatment times (0, 1, 12 and 24 h). Results suggested that enzyme application method did not affect rumen fermentation, ruminal enzyme activity and total tract apparent digestibility. Nutrient degradation rate and effective degradability of DM, NDF and ADF increased with increasing enzyme level and pre-treatment times. Degradation of nutrients was affected by enzymes levels or pre-treatment times. Therefore, it is probable that the improved degradation may be due to the supplemented exogenous hydrolytic enzymes under a certain condition.

• 한국환경과학회지
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• 제15권2호
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• pp.177-183
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• 2006

The hydrolytic kinetics of biodegradable poly(l-lactide) (PLLA) have been studied by using two model systems, solution-grown single crystal (SC) and Langmuir monolayer techniques, for elucidating the mechanism for both alkaline and enzymatic degradations. The present study investigated the parameters such as degradation medium and time. The Langmuir mono layers of PLLA showed faster rates of hydrolysis when they were exposed to a basic subphase rather than they did when exposed to neutral subphase. Both degradation mediums had moderate concentrations to show a maximized activity, depending on their sizes. An alkaline degradation of SCs of PLLA showed the decrease of molecular weight of the remained crystals due to the erosion of chain-folding surface. However, the enzymatic degradation of SCs of PLLA occurred in the crystal edges thus the molecular weight of remained crystals was not changed. This behavior might be attributed to the size of enzymes which is much larger than that of alkaline ions; that is, the enzymes need larger contact area with monolayers to be activated.

• Journal of Microbiology and Biotechnology
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• 제25권11호
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• pp.1773-1781
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• 2015

Environmental security is one of the major concerns for the safety of living organisms from a number of harmful pollutants in the atmosphere. Different initiatives, legislative actions, as well as scientific and social concerns have been discussed and adopted to control and regulate the threats of environmental pollution, but it still remains a worldwide challenge. Therefore, there is a need for developing certain sensitive, rapid, and selective techniques that can detect and screen the pollutants for effective bioremediation processes. In this perspective, isolated enzymes or biological systems producing enzymes, as whole cells or in immobilized state, can be used as a source for detection, quantification, and degradation or transformation of pollutants to non-polluting compounds to restore the ecological balance. Biosensors are ideal for the detection and measurement of environmental pollution in a reliable, specific, and sensitive way. In this review, the current status of different types of microbial biosensors and mechanisms of detection of various environmental toxicants are discussed.

• 한국미생물생명공학회:학술대회논문집
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• 한국미생물생명공학회 2001년도 Proceedings of 2001 International Symposium
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• pp.179-182
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• 2001

Two intracellular enzymes, cellobiose phosphorylase (CBP) and cellodextrin phosphorylase (CDP) are involved in the phosphorolytic pathway in cellulose degradation. Those enzymes are considered to be useful in syntheses of oligosaccharides because the reactions are reversible. CBP from Cellvibrio gilvus and CDP from Clostridium thermocellum YM-4 were cloned and over-expressed in Escharichia coli. Both the enzyme reactions showed ordered bi bi mechanism. Acceptor specificity of CBP in the reverse reaction was determined. Several $\beta$-l,4-glucosyl disaccharides were synthesized by using the reaction. A new substrate inhibition pattern, competitive substrate inhibition, was also found in the reverse reaction of CBP Cellobiose was produced from sucrose at a high yield by a combined action of three enzymes including CBP

• Journal of Microbiology and Biotechnology
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• 제19권6호
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• pp.573-581
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• 2009

The complex enzyme pool secreted by the phytopathogenic fungus Fusarium graminearum in response to glucose or hop cell wall material as sole carbon sources was analyzed. The biochemical characterization of the enzymes present in the supernatant of fungal cultures in the glucose medium revealed only 5 different glycosyl hydrolase activities; by contrast, when analyzing cultures in the cell wall medium, 17 different activities were detected. This dramatic increase reflects the adaptation of the fungus by the synthesis of enzymes targeting all layers of the cell wall. When the enzymes secreted in the presence of plant cell wall were used to hydrolyze pretreated crude plant material, high levels of monosaccharides were measured with yields approaching 50% of total sugars released by an acid hydrolysis process. This report is the first biochemical characterization of numerous cellulases, hemicellulases, and pectinases secreted by F. graminearum and demonstrates the usefulness of the described protein cocktail for efficient enzymatic degradation of plant cell wall.

• Journal of Microbiology and Biotechnology
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• 제6권6호
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• pp.425-431
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• 1996

The enzymatic characteristics of Alcaligenes latus were investigated by measuring the variations of various enzyme activities related to biosynthesis and degradation of poly-${\beta}$-hydroxybutyrate (PHB) during cultivation. All PHB biosynthetic enzymes, ${\beta}$-ketothiolase, acetoacetyl-CoA reductase, and PHB synthase, were activated gradually at the PHB accumulation stage, and the PHB synthase showed the highest value among three enzymes. This indicates that the rate of PHB biosynthesis is mainly controlled by either ${\beta}$-ketothiolase or acetoacetyl-CoA reductase rather than PHB synthase. The enzymatic activities related to the degradation of PHB were also measured, and the degradation of PHB was controlled by the activity of PHB depolymerase. The effect of supplements of metabolic regulators, citrate and tyrosine, was also investigated, and the activity of glucose-6-phosphate dehydrogenase was increased by metabolic regulators, especially by tyrosine. The activities of ${\beta}$-ketothiolase and acetoacetyl-CoA reductase were also activated by citrate and tyrosine, while the activity of PHB depolymerase was depressed. The increased rate and yield of PHB biosynthesis by metabolic regulators may be due to the increment of acetyl-CoA concentration either by the repression of the TCA cycle by citrate through product inhibition or by the activation of sucrose metabolism by the supplemented tyrosine.