Resin acid degradation by bacterial strains grown on CTMP effluent

All resin acids are diterpenoid carboxylic acids that are components of softwood extractives and they are known to contribute to much of the toxicity of pulp mill effluents. Although biological treatment systems can efficiently remove resin acids during normal operating conditions, resin acid breakthroughs occasionally occur. Recently we isolated five bacterial strains from bleach kraft effluents that degrade dehydroabietic acid (DHA), a resin acid commonly found in effluents. In this study we examined the ability of two bacterial strains (BKME 5 and BKME 9) to grow on chemithermomechanical pulping (CTMP) effluent and degrade DHA. Both of the strains could grow on CTMP effluents, but did not degrade DHA. COD measurement showed that both strains used other organic substrates in CTMP effluent. When nutrients (NH4⊕, PO43−, minerals and vitamins) were added to the effluent, both growth and DHA degradation increased significantly. The strains used DHA and other organic sources in the CTMP effluent simultaneously. The stimulated growth resulting from use of other organic material did not increase the rate of DHA degradation. It was found that ammonium played an important role in the DHA degradation of both strains. Without added ammonium, DHA degradation did not occur. Other nutrients also played important roles in DHA degradation by BKME 9.

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Microbiology and biodegradation of resin acids in pulp mill effluents: a minireview

Canadian Journal of Microbiology ◽

10.1139/m97-086 ◽

1997 ◽

Vol 43 (7) ◽

pp. 599-611 ◽

Cited By ~ 59

Author(s):

Steven N. Liss ◽

Paul A. Bicho ◽

John N. Saddler

Keyword(s):

Biological Treatment ◽

Resin Acid ◽

Pulp Mill ◽

Paper Mill ◽

Transformation Products ◽

Conclusive Evidence ◽

Resin Acids ◽

Original Material ◽

Pulp And Paper Mill ◽

Pulp Mill Effluents

Resin acids, a group of diterpenoid carboxylic acids present mainly in softwood species, are present in many pulp mill effluents and toxic to fish in recipient waters. They are considered to be readily biodegradable. However, their removal across biological treatment systems has been shown to vary. Recent studies indicate that natural resin acids and transformation products may accumulate in sediments and pose acute and chronic toxicity to fish. Several resin acid biotransformation compounds have also been shown to bioaccumulate and to be more resistant to biodegradation than the original material. Until recently, the microbiology of resin-acid degradation has received only scant attention. Although wood-inhabiting fungi have been shown to decrease the level of resin present in wood, there is no conclusive evidence that fungi can completely degrade these compounds. In contrast, a number of bacterial isolates have recently been described which are able to utilize dehydroabietic or isopimaric acids as their sole carbon source. There appears to be an unusually high degree of substrate specificity with respect to the utilization of abietane congeners and the presence of substituents. Pimaranes do not appear to be attacked to the same extent as the abietanes. This paper reviews the occurrence, chemistry, toxicity, and biodegradation of resin acids in relation to the biological treatment of pulp and paper mill effluents.Key words: resin acids, biodegradation, pulp mill effluents.

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Isolation and characterization of thermophilic bacteria capable of degrading dehydroabietic acid

Canadian Journal of Microbiology ◽

10.1139/w99-028 ◽

1999 ◽

Vol 45 (6) ◽

pp. 513-519 ◽

Cited By ~ 21

Author(s):

Zhongtang Yu ◽

William W Mohn

Keyword(s):

Thermophilic Bacteria ◽

Resin Acid ◽

Pulp Mill ◽

Maximum Growth ◽

Dehydroabietic Acid ◽

Resin Acids ◽

Bacterial Strains ◽

Rdna Sequences ◽

Isolation And Characterization ◽

Continuous Enrichment

Using a semi-continuous enrichment method, we isolated two thermophilic bacterial strains, which could completely degrade abietane resin acids, including dehydroabietic acid (DhA). Strain DhA-73, isolated from a laboratory-scale bioreactor treating bleached kraft mill effluent at 55°C, grew on DhA as sole carbon source; while DhA-71, isolated from municipal compost, required dilute tryptic soy broth for growth on DhA. DhA-71 grew on DhA from 30°C to 60°C with maximum growth at 50°C; while, DhA-73 grew on DhA from 37°C to 60°C with maximum growth at 55°C. At 55°C, the doubling times for DhA-71 and DhA-73 were 3.3 and 3.7 h, respectively. DhA-71 and DhA-73 had growth yields of 0.26 and 0.19 g of protein per g of DhA, respectively. During growth on DhA, both strains converted DhA to CO2, biomass, and dissolved organic carbon. Analyses of the 16S-rDNA sequences of these two strains suggest that they belong to two new genera in theRubrivivax subgroup of the beta subclass of the Proteobacteria. Strains DhA-71 and DhA-73 are the first two bacteria isolated and characterized that are capable of biodegradation of resin acids at high temperatures. This study provided direct evidence for biodegradation of resin acids and feasibility for biotreatment of pulp mill effluent at elevated temperatures.Key words: biodegradation, resin acid, semi-continuous enrichment, thermophiles.

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Limitations for Biological Removal of Resin Acids from Pulp Mill Effluent

Water Science & Technology ◽

10.2166/wst.1999.0723 ◽

1999 ◽

Vol 40 (11-12) ◽

pp. 281-288 ◽

Cited By ~ 12

Author(s):

A. G. Werker ◽

Eric R. Hall

Keyword(s):

Biological Treatment ◽

Biological Systems ◽

Resin Acid ◽

Pulp Mill ◽

Operating Conditions ◽

Resin Acids ◽

Continuous Treatment ◽

Pulp Mills ◽

Fundamental Study ◽

Biological Removal

This paper highlights results from a fundamental study into the fate of resin acids during biological treatment. Pulp mills in Canada rely on biological treatment systems for the removal of resin acids that are released from wood during pulping and bleaching. These are priority contaminants for the pulping industry since they have been associated with events of toxicity breakthrough. Although tighter mill control has helped to minimise the frequency of these events, it would be useful to have an understanding of the basic limitations of biological systems as the last line of defence for limiting resin acid discharges. The dependence of physico-chemical and biological phenomena on pH will influence the chances for successful biological removal of resin acids. Changes in pH within the typical range used for biological treatment significantly alter the bioavailability of resin acids and the ecology of the microorganisms responsible for their degradation. Changes in resin acid loading during continuous treatment also affect the microbial ecology. Further, the capacity of a treatment system to degrade resin acids is a function of the contaminant loading. Time delays for microbial community acclimation in response to a shift-up in loading are significantly long and are also a function of pH. The capacity to remove resin acids is readily gained and lost in a biological system. Hence the bioreactor operating conditions in conjunction with the period and amplitude of loading fluctuations can impact on the extent of biological removal for resin acids. Consequently, biological systems can be severely compromised by influent transient loading when it comes to the removal of specific contaminants like resin acids.

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Characterization oftdtgenes for the degradation of tricyclic diterpenes byPseudomonas diterpeniphilaA19-6a

Canadian Journal of Microbiology ◽

10.1139/w01-127 ◽

2002 ◽

Vol 48 (1) ◽

pp. 49-59 ◽

Cited By ~ 16

Author(s):

C A Morgan ◽

R C Wyndham

Keyword(s):

Gene Knockout ◽

Resin Acid ◽

Pulp Mill ◽

Ring Structure ◽

Resin Acids ◽

P450 Monooxygenase ◽

Aquatic Life ◽

Degrading Bacterium ◽

Coa Ligase ◽

Pulp Mill Effluents

Resin acids are tricyclic diterpenes that are toxic to aquatic life when released in high concentrations in pulp mill effluents. These naturally formed organic acids are readily degraded by bacteria and fungi; nevertheless, many of the mechanisms involved are still unknown. We report the localization, cloning, and sequencing of genes for abietane degradation (9.18 kb; designated tdt (tricyclic diterpene) LRSABCD) from the γ-Proteobacterium Pseudomonas diterpeniphila A19-6a. Using gene knockout mutants, we demonstrate that tdtL, encoding a putative CoA ligase, is required for growth on abietic and dehydroabietic acids. A second gene knockout in tdtD, encoding a putative cytochrome P450 monooxygenase, reduced the growth of strain A19-6a on abietic and dehydroabietic acids as sole sources of carbon and energy, but did not eliminate growth. The degree of homology between P450TdtDand P450TerpC, the closest known P450 homologue to TdtD, identifies TdtD as a new member of the P450 superfamily. Hybridization of six of the tdt genes to genomic DNA of a related resin acid degrading bacterium Pseudomonas abietaniphila BKME-9 identified tdt homologues in this strain that utilizes aromatic ring dioxygenase genes (dit) to open the ring structure of abietic and dehydroabietic acids. These results suggest the tdt and dit genes may function in concert to allow these Pseudomonas strains to degrade resin acids. Homologues of several of the tdt genes were detected in resin acid degrading Ralstonia and Comamonas species within the β- and γ-Proteobacteria.Key words: resin acid, tdt gene, biodegradation, Pseudomonas.

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