• Journal of Microbiology and Biotechnology
• /
• 제22권10호
• /
• pp.1311-1323
• /
• 2012

In the present work, current knowledge on the potential fate, microbial degradation, and toxicity of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) was thoroughly reviewed, focusing on the toxicological assessment of a variety of potential RDX degradation pathways in bacteria and fungi. The present review on microbial degradation pathways and toxicities of degradation intermediates suggests that, among aerobic RDX degradation pathways, the one via denitration may be preferred in a toxicological perspective, and that among anaerobic pathways, those forming 4-nitro-2,4-diazabutanal (NDAB) via ring cleavage of 1-nitroso-3,5-dinitro-1,3,5-triazinane (MNX) may be toxicologically advantageous owing to its potential mineralization under partial or complete anoxic conditions. These findings provide important information on RDX-degrading microbial pathways, toxicologically most suitable to be stimulated in contaminated fields.

• Environmental Engineering Research
• /
• 제25권4호
• /
• pp.597-604
• /
• 2020

In the present study, the application of sequential biological and photocatalytic process was evaluated as a feasible process for the degradation of imidacloprid (IMI) in soil. Photocatalysis was carried out as a post and pre-treatment to the biological process as Microbial Photocatalytic (MP) and Photocatalytic Microbial (PM), respectively, to enhance the degradation and mineralization of IMI in soil. By both the processes, there was an enhancement in the percentage degradation of IMI i.e 86.2% for PM and 94.6% for MP process. The obtained results indicate that MP process is apparently more efficient in degradation of IMI which was observed with 15 days of biological treatment followed by 18 h of photocatalytic degradation (15 d + 18 h). The present work also reveals that though the difference in terms of the degradation of IMI after 5 d + 18 h, 10 d + 18 h & 15 d+ 18 h of MP process is not drastic, yet significant variation has been observed in terms of mineralization that truly signifies the removal of IMI from the soil. The LC analysis has shown that the intermediates formed during MP process are more and smaller in comparison to PM process, which further provides evidence that MP process is better than PM process for effective degradation of IMI in soil.

• Asian-Australasian Journal of Animal Sciences
• /
• 제9권5호
• /
• pp.519-524
• /
• 1996

An investigation was carried out to study the microbial colonization and degradation of five crop residues, viz., sago waste, rice straw, oil palm trunk shavings, untreated palm press fibre and palm press fibre teated with 3% ammonium hydroxide in the rumen of goats. Colonisation by rumen bacteria and fungi was already established on all the five crop residues 8 h after incubation. However, the extent of colonization varied among the crop residues. Microbial colonization was poor on palm press fibre (treated and untreated) but more extensive on sago waste, oil palm trunk shavings and rice straw. By 24 h, most of the soft-walled tissues in sago waste, rice straw and oil palm trunk shavings were degraded leaving the thick-walled tissues extensively colonized by bacteria and fungi. Degradation on palm press fibre was still limited. At 48 h, the thick-walled tissues of sago waste, oil palm trunk shavings and rice straw showed various degrees of degradation - from small erosion zones to large digested areas. Bacterial growth was similar to that at 24 h but fungal growth was less. On palm press fibre, microbial colonization was more extensive than at 24 h but degradation of the fibres was still limited. Degradation of all the five crop residues at 72 h was somewhat similar to that at 48 h. Overall, microbial colonization and degradation were the most extensive on sago waste, followed by rice straw and oil palm trunk shavings, and the least on palm press fibre (treated and untreated). Dry matter loss of the five crop residues at the various incubation periods also showed the same order of degradation.

• KSBB Journal
• /
• 제16권1호
• /
• pp.61-65
• /
• 2001

BTX를 배출하는 지역에서 얻어진 슬러지를 적절한 배지에 3개월 간 적응시킨 결과, benzene과 toluene을 빠르게 분해하는 MY컨소시엄와 p-, m-, o-xylene을 빠르게 분해하는 MA컨소시엄을 획득하였다. 균주의 동정결과 MA 및 MA컨소시엄의 주된 균주는 Rhodococcus ruber DSM 43338T과 Rhodococcus sp.로 밝혀졌다. BTX 단일성분의 분해속도 측정결과 benzene > toluene > o-xylene > p-xylene > m-xylene의 순으로 분해가 일어났다. MY 및 MY컨소시엄으 동시배양을 이용한 2-5종의 복합 BTX의 분해실험결과 대부분의 경우 108시간내에 완전히 분해되었으며, 각 혼합물의 조성에 따라 촉진 및 방해작용을 나타내었다. 분 연구에서 획득한 2종의 미생물컨소시엄은 BTX의 생물학적 처리에 매우 유용하게 사용될 수 있을 것으로 사료된다.

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

• 한국환경과학회지
• /
• 제11권12호
• /
• pp.1315-1320
• /
• 2002

Since the enzymatic degradation of microbial poly[(R)-3-hydroxybutyrate-co-3-hydroxyvalerate] (P(3HB-co-3HV)) initially occurs by a surface erosion process, a degradation behavior could be controlled by the change of surface property. In order to control the rate of enzymatic degradation, plasma gas discharge and blending techniques were used to modify the surface of microbial P(3HB-co-3HV). The surface hydrophobic property of P(3HB-co-3HV) film was introduced by CF$_3$H plasma exposure. Also, the addition of small amount of polystyrene as a non-degradable polymer with lower surface energy to P(3HB-co-3HV) has been studied. The enzymatic degradation was carried out at 37 $^{\circ}C$ in 0.1 M potassium phosphate buffer (pH 7.4) in the presence of an extracellular PHB depolymerase purified from Alcaligenes facalis T1. Both results showed the significant retardation of enzymatic erosion due to the hydrophobicity and the enzyme inactivity of the fluorinated- and PS-enriched surface layers.

• Asian-Australasian Journal of Animal Sciences
• /
• 제30권2호
• /
• pp.171-180
• /
• 2017

Objective: This study investigated the association of enzyme-producing microbes and their enzymes with starch and hemicellulose degradation during fermentation of total mixed ration (TMR) silage. Methods: The TMRs were prepared with soybean curd residue, alfalfa hay (ATMR) or Leymus chinensis hay (LTMR), corn meal, soybean meal, vitamin-mineral supplements, and salt at a ratio of 25:40:30:4:0.5:0.5 on a dry matter basis. Laboratory-scale bag silos were randomly opened after 1, 3, 7, 14, 28, and 56 days of ensiling and subjected to analyses of fermentation quality, carbohydrates loss, microbial amylase and hemicellulase activities, succession of dominant amylolytic or hemicellulolytic microbes, and their microbial and enzymatic properties. Results: Both ATMR and LTMR silages were well preserved, with low pH and high lactic acid concentrations. In addition to the substantial loss of water soluble carbohydrates, loss of starch and hemicellulose was also observed in both TMR silages with prolonged ensiling. The microbial amylase activity remained detectable throughout the ensiling in both TMR silages, whereas the microbial hemicellulase activity progressively decreased until it was inactive at day 14 post-ensiling in both TMR silages. During the early stage of fermentation, the main amylase-producing microbes were Bacillus amyloliquefaciens (B. amyloliquefaciens), B. cereus, B. licheniformis, and B. subtilis in ATMR silage and B. flexus, B. licheniformis, and Paenibacillus xylanexedens (P. xylanexedens) in LTMR silage, whereas Enterococcus faecium was closely associated with starch hydrolysis at the later stage of fermentation in both TMR silages. B. amyloliquefaciens, B. licheniformis, and B. subtilis and B. licheniformis, B. pumilus, and P. xylanexedens were the main source of microbial hemicellulase during the early stage of fermentation in ATMR and LTMR silages, respectively. Conclusion: The microbial amylase contributes to starch hydrolysis during the ensiling process in both TMR silages, whereas the microbial hemicellulase participates in the hemicellulose degradation only at the early stage of ensiling.

• 환경위생공학
• /
• 제14권1호
• /
• pp.24-30
• /
• 1999

A biological filter for treatment of toluene among volatile organic compounds was studied. The investigation was conducted using specially built stainless steel columns packed with granular activated carbon and cold for removal of toluene. The G.A. and mold as filter material was also coated with Pseudomonas putida microorganisms.The biofilter unit was operated in the condition of moisture content vairation at gas loading rate of 12.5 l/min. Gaseous toluene taken from tedlar bag was analyzed by the use of G.C equipped with F.I.d detector. The removal efficiency of gaseous toluene was 95% at average inlet concentration of 950 ppm during bio-degradation operating condition. Effective removal efficiency was obtained with moisture content 27.5% at activated carbon and 32% at mold in this study. The effective operating condition were obtained with pH 6-8, temperature 28-42℃ for microbial degradation at gas loading rate of 12.5 l/min in packed material.

• 미생물학회지
• /
• 제27권2호
• /
• pp.139-146
• /
• 1989

담수상태의 논토양에 처리한 유기인계 살충제 diazinon의분해기작과 그 분해산물에 대하여 조사하였다. 항온조건($30^{\circ}C$)하에서 살균토양에 비하여 비살균토양에서의 diazinon 분해가 보다 빠르게 일어남으로써 담수토양내 diazinon 분해에 미생물의 대사활동이 매우 종요한 것으로 나타났는데, 비살균토양내 diazinon의 반감기는 약 2일이엇고 항온반응 7일만에 95% 이상의 분해가 이루어졌다. 또한 diazinon 분해기간 중 미생물 개체수와 아울러 토양내 monoxygenase 및 esterase 활성의 증가가 이루어졌으며 이는 토양내 diazinon 처리가 이 약제의 분해와 관련된 미생물학적 요인의 생장 또는 활성을 촉진시키고 있음을 보여준다. 이와 관련하여 담수토양내 diazinon 분해산물로서 esterase 작용에 의한 2-isopropyl-6-methyl-4-hydroxy pyrimidine 이외에 monooxygenase에 의한 diazoxon과 hydroxydiazinon, 그리고 sulfotep 등이 mass spectrometry에 의하여 확인되었다.

• 한국식품영양학회지
• /
• 제4권1호
• /
• pp.99-107
• /
• 1991

Lignocellulose and lignolic compounds were absolutely given much weight In the biosphere, and their degradation was essential for continuous biological carbon circulation. Whereas aerobic cellulolytic microorganism dissolved the cellulose into their elements in the first stage, strict anaerobic cellulolytic microorganism's role was taken I increasing interest through the recent research. It was reviewed that anaerobic microbial degradation process of lignocellulose and its derivatives (cellulose, lignin, oligolignol and monoaromatic compound), and function of anaerobic microorganism on the. environmental ecology.