Evaluation of biodegradation of nonylphenol ethoxylate and lignin by combining toxicity assessment and chemical characterization.

The aerobic biodegradation of commercial nonylphenol ethoxylate (NPE) mixture and alkali lignin was studied using the OECD headspace test accompanied by the simultaneous measurement of ecotoxicity directly from the biodegradation liquors and by the follow-up of the chemical composition of the studied chemicals. NPE degradation was dependent on the inoculum source: approximately 40% of NPE was mineralized into CO(2) during the 4-week experiment when inoculum from Helsinki City wastewater treatment plant (WWTP) was used, and only 12% was mineralized when inoculum from Jyväskylä City WWTP was used. Chemical analyses revealed a shift in the ethoxylate chain length from longer to shorter soon after the beginning of the NPE biodegradation tests. At the same time also toxicity (reverse electron transport assay, RET) and estrogenic activity (human estrogen receptor yeast) measured directly from the biodegradation liquors decreased. In case of alkali lignin, approximately 11% was mineralized in the test and chemical analysis showed in maximum a 30% decrease in lignin concentration. Toxicity of lignin biodegradation liquors started to decrease in the beginning of the test, but became more toxic towards the end of the test again. Especially RET assay proved to be sensitive enough for measuring toxicity changes directly from biodegradation liquors, although a concentrating treatment of the liquors is recommended for a more detailed characterization and identification of toxic metabolites.

Comparing steroid estrogen, and nonylphenol content across a range of European sewage plants with different treatment and management practices.

The effluent of 17 sewage treatment works (STW) across Norway, Sweden, Finland, The Netherlands, Belgium, Germany, France and Switzerland was studied for the presence of estradiol (E2), estrone (E1), ethinylestradiol (EE2) and nonylphenol (NP). Treatment processes included primary and chemical treatment only, submerged aerated filter, oxidation ditch, activated sludge (AS) and combined trickling filter with activated sludge. The effluent strength ranged between 87 and 846 L/PE (population equivalent), the total hydraulic retention time (HRT) ranged between 4 and 120 h, sludge retention time (SRT) between 3 and 30 d, and water temperature ranged from 12 to 21 degrees C. The highest estrogen values were detected in the effluent of the STW which only used primary treatment (13 ng/L E2 and 35 ng/L E1) and on one occasion in one of the STW using the AS system (6.5 ng/L E2, 50.5 ng/L E1, but on three other occasions the concentrations in this STW were at least a factor of 6 lower). For the 16 STW employing secondary treatment E2 was only detected in the effluent of six works during the study period (average 0.7-5.7 ng/L). E1 was detected in the effluent of 13 of the same STW. The median value for E1 for the 16 STW with secondary treatment was 3.0 ng/L. EE2 was only detected in two STW (1.1, <0.8-2.8 ng/L). NP could be detected in the effluent of all 14 STW where this measurement was attempted, with a median of 0.31 microg/L and values ranging from 0.05 to 1.31 microg/L. A comparison of removal performance for E1 was carried out following prediction of the probable influent concentration. A weak but significant (alpha<5%) correlation between E1 removal and HRT or SRT was observed.

Effects of pulp mill effluents and restricted diet on growth and physiology of rainbow trout (Oncorhynchus mykiss).

Juvenile female rainbow trout was exposed for 4.5 months (June to October) to two dilutions of untreated and activated sludge treated whole mill effluent from a pulp mill producing bleached ECF pulp. Two controls were used, on fed ad libitum and a second receiving 0.5% feed of the body weight. All effluent exposed groups were fed ad libitum. Mean weight of the fish was measured monthly. At the end of the experiment a number of physiological and biochemical parameters were analyzed in order to establish the physiological status of the exposed fish in comparison with unexposed fish that obtained ad libitum or restricted amount of feed. The fish exposed to treated effluent grew significantly more than ad libitum control fish until August, whereupon growth retarded in fish exposed to the lower effluent dilution (400 v/v). The growth of fish exposed to untreated effluent did not deviate significantly from the control fed ad libitum. The results from the hematological analysis clearly showed that fish fed restricted amount of feed deviated significantly in most parameters compared with the control fed ad libitum. Fish exposed to treated effluent showed a response pattern similar to that of the control fed restricted amount of feed, whereas the fish exposed to untreated effluent showed a response pattern that did not deviate from that of the ad libitum control. The metabolic parameters suggested that fish exposed to treated effluent had a higher metabolic demand than ad libitum control and that the energy allocation at the end of the experiment was directed to processes other than growth. The responses on hematology were mainly a consequence of the increased energy demand and were not primary effects. The implications of using feed related parameters at field studies are discussed.

Treatment with thiamine hydrochloride and astaxanthine for the prevention of yolk-sac mortality in Baltic salmon fry (M74 syndrome).

Two practical methods are reported for treating feral Baltic salmon with thiamine hydrochloride against M74 syndrome (abnormally high yolk-sac fry mortality of the Baltic salmon). Both bathing of the yolk-sac fry in thiamine hydrochloride (1000 mg l-1, 1 h) and a single intraperitoneal injection given to the female brood fish (100 mg kg-1 fish) during the summer 3 mo before stripping were shown to elevate the whole body total thiamine concentration in the fry. Both treatments were also shown to be effective in preventing mortality due to M74 syndrome. The effect of bathing the yolk-sac fry was shown to be dose-dependent. The results support the view that there is a causal relationship between the thiamine status of the yolk-sac fry and M74 mortality. An intraperitoneal injection of astaxanthine suspension administered to the female brood fish (11 mg kg-1 fish) in the summer 3 mo before stripping elevated the astaxanthine concentration in the eggs but did not affect mortality due to M74 syndrome. An interaction between astaxanthine and thiamine may occur in the developing embryo or yolk-sac fry, however. No association could be demonstrated between the various thiamine hydrochloride treatment practices and hepatic cytochrome P450 dependent 7-ethoxyresorufin-O-deethylase (EROD) activity in the yolk-sac fry. An injection of thiamine hydrochloride into the peritoneal cavity of wild Baltic salmon females could be used to raise thiamine concentrations in their offspring in the rivers. The effect on smolt production in Finnish Baltic salmon rivers needs to be investigated further, however.

Isolation of Trichoderma reesei genes highly expressed on glucose-containing media: characterization of the tef1 gene encoding translation elongation factor 1 alpha.

Genes that are highly expressed on glucose-containing media were isolated from the filamentous fungus, Trichoderma reesei. A cDNA bank was prepared from glucose-grown fungus, the bank was screened with the same cDNA as a probe, and clones giving the strongest signal were isolated. This resulted in the isolation of previously uncharacterized genes. Five of the genes, representing the most abundant transcripts, corresponded to 1-3% of the total mRNA population and were clearly more highly expressed than the phosphoglycerate kinase-encoding gene (pgk1) of T. reesei. Based on sequence homology, one of the genes was identified as tef1, encoding translation elongation factor 1 alpha (TEF). The T. reesei TEF is most related to the Mucor racemosus TEF3, showing an overall amino acid similarity of 85%. Interestingly, an exon of only 2 bp seems to be present in T. reesei tef1, comprising the first 2 bp of the Gly15 codon.

The Bacillus subtilis cytochrome-c oxidase. Variations on a conserved protein theme.

The structural genes of cytochrome-c oxidase in Bacillus subtilis have been isolated and sequenced. Five genes, ctaB-F, are closely spaced. ctaC, ctaD, ctaE and ctaF are the genes for subunits II, I, III and IVB, respectively, ctaB, which may encode an assembly factor, is separated and upstream from the others. In comparison to its mitochondrial counterparts, subunit I has an extended C-terminus with two additional transmembrane segments, whereas subunit III has lost two such segments from its N-terminus. The C-terminal extension in subunit II is a covalent cytochrome-c domain, previously characterized only in the thermophilic oxidases. Subunit IVB, a small hydrophobic protein, is a novel subunit. These predictions suggest that the B. subtilis cytochrome-c oxidase is structurally more related to the four-subunit Escherichia coli cytochrome-bo complex than, for instance, to the Paracoccus denitrificans enzyme. Cytochrome aa3, which was previously isolated from B. subtilis [de Vrij, W., Azzi, A. & Konings, W. N. (1983) Eur. J. Biochem. 131, 97-103] is not encoded by the ctaC-F genes; thus, there seems to be two different cytochrome-aa3-type oxidases in this Gram-positive bacterium.

Deletion of the gene for subunit III leads to defective assembly of bacterial cytochrome oxidase.

COIII is one of the major subunits in the mitochondrial and a bacterial cytochrome c oxidase, cytochrome aa3. It does not contain any of the enzyme's redox-active metal centres and can be removed from the enzyme without major changes in its established functions. We have deleted the COIII gene from Paracoccus denitrificans. The mutant still expresses spectroscopically detectable enzyme almost as the wild-type, but its cytochrome c oxidase activity is much lower. From 50 to 80% of cytochrome a is reduced and its absorption maximum is 2-3 nm blue-shifted. The EPR signal of ferric cytochrome a is heterogeneous indicating the presence of multiple cytochrome a species. Proteolysis of the membrane-bound oxidase shows new cleavage sites both in COI and COII. DEAE-chromatography of solubilized enzyme yields fractions that contain a COI + COII complex and in addition haem-binding, free COI as well as free COII. The mutant phenotype can be complemented by introducing the COIII gene back to cells in a plasmid vector. We conclude that cytochrome oxidase assembles inefficiently in the absence of COIII and that this subunit may facilitate a late step in the assembly. The different oxidase species in the mutant represent either accumulating intermediates of the assembly pathway or dissociation products of a labile COI + COII complex and its conformational variants.