scholarly journals Degradation Mechanism of Kraft Pulp Wastewater with Ozone and Microbial Degradation of Organic Acids Produced.

2001 ◽  
Vol 11 (1) ◽  
pp. 43-49 ◽  
Author(s):  
Yoshitoshi NAKAMURA ◽  
Masaki KOMORI ◽  
Tatsuro SAWADA
Keyword(s):  
Organic Acids ◽  
Microbial Degradation ◽  
Kraft Pulp ◽  
Degradation Mechanism

scholarly journals Enhanced degradation mechanism of tetracycline by MnO2 with the presence of organic acids

Chemosphere ◽  
2021 ◽  
pp. 131606
Author(s):  
Siyang Sun ◽  
Yuhan Wang ◽  
Lin Zhou ◽  
Xiaoyu Wang ◽  
Chunli Kang
Keyword(s):  
Organic Acids ◽  
Degradation Mechanism ◽  
Enhanced Degradation

Microbial Degradation Mechanism and Pathway of the Novel Insecticide Paichongding by a Newly Isolated Sphingobacterium sp. P1-3 from Soil

2015 ◽  
Vol 63 (15) ◽  
pp. 3823-3829 ◽  
Author(s):  
Zhiqiang Cai ◽  
Wenjie Zhang ◽  
Shanshan Li ◽  
Jiangtao Ma ◽  
Jing Wang ◽  
...  
Keyword(s):  
Microbial Degradation ◽  
Degradation Mechanism ◽  
The Novel

Microbial treatment of kraft pulp wastewater pretreated with ozone

1997 ◽  
Vol 35 (2-3) ◽  
pp. 277-282 ◽  
Author(s):  
Y. Nakamura ◽  
T. Sawada ◽  
F. Kobayashi ◽  
M. Godliving
Keyword(s):  
Oxalic Acid ◽  
Organic Acids ◽  
Activated Sludge ◽  
Polyurethane Foam ◽  
Maleic Acid ◽  
Kraft Pulp ◽  
Microbial Growth ◽  
Alkaline Condition ◽  
Substrate Consumption ◽  
Effects Of Ph

Kraft pulp wastewater was treated with a combination of ozone and activated sludge. The effects of pH on the degradation of lignin and the production of organic acids were examined experimentally in the ozonolysis of wastewater. The strong alkaline condition enhanced not only the degradation of lignin but also the production of organic acids. The dynamic behaviours of microbial growth and substrate consumption were investigated in the biodegradation of organic acids using activated sludge. Maleic acid and oxalic acid in the ozonized wastewater were degraded completely by the activated sludge. The immobilized activated sludge culture using polyurethane foam was effective in degrading organic acids.

Microbial degradation mechanism of pyridine by Paracoccus sp. NJUST30 newly isolated from aerobic granules

2018 ◽  
Vol 344 ◽  
pp. 86-94 ◽  
Author(s):  
Jing Wang ◽  
Xinbai Jiang ◽  
Xiaodong Liu ◽  
Xiuyun Sun ◽  
Weiqing Han ◽  
...  
Keyword(s):  
Microbial Degradation ◽  
Degradation Mechanism ◽  
Aerobic Granules

scholarly journals Using Low Molecular Weight Organic Acids to Enhance Microbial Degradation of Polycyclic Aromatic Hydrocarbons: Current Understanding and Future Perspectives

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 446
Author(s):  
Lei Zhang ◽  
Jie Qiao ◽  
Haiyang Cui ◽  
Minghui Wang ◽  
Xiujuan Li
Keyword(s):  
Molecular Weight ◽  
Polycyclic Aromatic Hydrocarbons ◽  
Organic Acids ◽  
Microbial Degradation ◽  
Aromatic Hydrocarbons ◽  
Current Understanding ◽  
Low Molecular Weight ◽  
Future Perspectives ◽  
Polycyclic Aromatic ◽  
The Impact

Polycyclic aromatic hydrocarbons (PAHs), an organic pollutant with persistence and carcinogenicity, are universally present in the environment and food processing. Biological approaches toward remediating PAHs-contaminated sites are a viable, economical, and environmentally friendly alternative compared to conventional physical and/or chemical remediation methods. Recently, various strategies relating to low molecular weight organic acids (LMWOAs) have been developed to enhance the microbial degradation of PAHs. However, the remaining challenge is to reveal the role of LMWOAs in the PAHs biodegradation process, and the latter limits researchers from expanding the application scope of biodegradation. In this mini-review, we summarized the current understanding of the impact of LMWOAs on (1) the physicochemical behavior of PAHs in the extracellular environment; (2) the interactions between PAHs and the microbial cell surface; and (3) the intracellular metabolization of PAHs. Future perspectives for this field are discussed in this review as well.

scholarly journals Role of Organic Acids in the Manganese-Independent Biobleaching System of Bjerkandera sp. Strain BOS55

1998 ◽  
Vol 64 (7) ◽  
pp. 2409-2417 ◽  
Author(s):  
María Teresa Moreira ◽  
Gumersindo Feijoo ◽  
Tünde Mester ◽  
Pablo Mayorga ◽  
Reyes Sierra-Alvarez ◽  
...  
Keyword(s):  
Organic Acids ◽  
Manganese Peroxidase ◽  
Superoxide Anion ◽  
Kraft Pulp ◽  
Veratryl Alcohol ◽  
White Rot ◽  
White Rot Fungus ◽  
Ph Buffering ◽  
Enhanced Production

ABSTRACT Bjerkandera sp. strain BOS55 is a white rot fungus that can bleach EDTA-extracted eucalyptus oxygen-delignified kraft pulp (OKP) without any requirement for manganese. Under manganese-free conditions, additions of simple physiological organic acids (e.g., glycolate, glyoxylate, oxalate, and others) at 1 to 5 mM stimulated brightness gains and pulp delignification two- to threefold compared to results for control cultures not receiving acids. The role of the organic acids in improving the manganese-independent biobleaching was shown not to be due to pH-buffering effects. Instead, the stimulation was attributed to enhanced production of manganese peroxidase (MnP) and lignin peroxidase (LiP) as well as increased physiological concentrations of veratryl alcohol and oxalate. These factors contributed to greatly improved production of superoxide anion radicals, which may have accounted for the more extensive biobleaching. Optimum biobleaching corresponded most to the production of MnP. These results suggest that MnP from Bjerkandera is purposefully produced in the absence of manganese and can possibly function independently of manganese in OKP delignification. LiP probably also contributed to OKP delignification when it was present.

Structures of c-di-GMP/cGAMP degrading phosphodiesterase VcEAL: identification of a novel conformational switch and its implication

2019 ◽  
Vol 476 (21) ◽  
pp. 3333-3353 ◽  
Author(s):  
Malti Yadav ◽  
Kamalendu Pal ◽  
Udayaditya Sen
Keyword(s):  
Active Site ◽  
Metal Binding ◽  
Metal Ion ◽  
Triosephosphate Isomerase ◽  
Catalytic Mechanism ◽  
Degradation Mechanism ◽  
Structural Basis ◽  
Conserved Residues ◽  
Phosphodiester Bond ◽  
Cyclic Dinucleotides

Cyclic dinucleotides (CDNs) have emerged as the central molecules that aid bacteria to adapt and thrive in changing environmental conditions. Therefore, tight regulation of intracellular CDN concentration by counteracting the action of dinucleotide cyclases and phosphodiesterases (PDEs) is critical. Here, we demonstrate that a putative stand-alone EAL domain PDE from Vibrio cholerae (VcEAL) is capable to degrade both the second messenger c-di-GMP and hybrid 3′3′-cyclic GMP–AMP (cGAMP). To unveil their degradation mechanism, we have determined high-resolution crystal structures of VcEAL with Ca2+, c-di-GMP-Ca2+, 5′-pGpG-Ca2+ and cGAMP-Ca2+, the latter provides the first structural basis of cGAMP hydrolysis. Structural studies reveal a typical triosephosphate isomerase barrel-fold with substrate c-di-GMP/cGAMP bound in an extended conformation. Highly conserved residues specifically bind the guanine base of c-di-GMP/cGAMP in the G2 site while the semi-conserved nature of residues at the G1 site could act as a specificity determinant. Two metal ions, co-ordinated with six stubbornly conserved residues and two non-bridging scissile phosphate oxygens of c-di-GMP/cGAMP, activate a water molecule for an in-line attack on the phosphodiester bond, supporting two-metal ion-based catalytic mechanism. PDE activity and biofilm assays of several prudently designed mutants collectively demonstrate that VcEAL active site is charge and size optimized. Intriguingly, in VcEAL-5′-pGpG-Ca2+ structure, β5–α5 loop adopts a novel conformation that along with conserved E131 creates a new metal-binding site. This novel conformation along with several subtle changes in the active site designate VcEAL-5′-pGpG-Ca2+ structure quite different from other 5′-pGpG bound structures reported earlier.

Prebleaching of eucalypt kraft pulp with OP stages: Effect of an acid pretreatment or chelation step

TAPPI Journal ◽  
2012 ◽  
Vol 11 (6) ◽  
pp. 31-38
Author(s):  
TATIANA M. PÓVOAS ◽  
DINA A.G. ANGÉLICO ◽  
ANA P.V. EGAS ◽  
PEDRO E.G. LOUREIRO ◽  
LICÍNIO M. GANDO-FERREIRA ◽  
...  
Keyword(s):  
Eucalyptus Globulus ◽  
Comparative Evaluation ◽  
Kraft Pulp ◽  
Kraft Pulps ◽  
Acid Pretreatment ◽  
High Brightness ◽  
Pulp Viscosity ◽  
Brightness Reversion

We conducted a comparative evaluation of different treatments for the bleaching of eucalypt kraft pulps beginning with OP stages. The treatments tested were (1) an acid chelation stage with DTPA (OQP sequence); (2) a hot acid stage (AOP sequence); and (3) a chelant addition into the alkaline oxygen stage ((OQ)P and A(OQ)P sequences). The latter strategy was also studied for environmental reasons, as it contributes to the closure of the filtrate cycle. The OQP sequence leads to the highest brightness gain and pulp viscosity and the lowest peroxide consumption caused by an efficient metals control. Considering that the low biodegradability of the chelant is a problem, the A(OQ)P sequence is an interesting option because it leads to reduced peroxide consumption (excluding OQP) while still reaching high brightness values and similar brightness reversion to OQP prebleaching, with only a viscosity loss of 160 dm3/kg. Therefore, a hot acid stage could be considered when a separate acid Q stage is absent in a prebleaching sequence of Eucalyptus globulus kraft pulps involving OP stages.

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