Algal-derived organic matter as precursors of disinfection by-products and mutagens upon chlorination.
ABSTRACT Algal-derived organic materials (including algal cells, hydrophilic and hydrophobic proteins) from Chlamydomonas sp. (a common green alga in local reservoirs), were chlorinated in the laboratory (20 °C, pH 7, Cl(2)/DOC ratio of 20 mg Cl(2) mg(-1)). Levels of disinfection by-products and mutagenicity (via Salmonella T100 mutation assay, -S9) over 2 h of chlorination time were determined. The hydrophilic proteins were more effective precursors of chloroform (35.9 μmol L(-1) at 120 min), 35 times greater than that from the hydrophobic proteins; whereas the hydrophobic proteins were more potent precursors of direct-acting mutagens (maximum level of 50.1 rev μL(-1) at 30 s) than the hydrophilic proteins (maximum level of 3.38 rev μL(-1) at 60 min). The mutagenicity of the chlorinated solutions generally reached a peak level shortly after chlorination and then declined afterwards, a pattern different from that of chloroform generation. The results indicate that algal hydrophilic proteins, containing low aromaticity and difficult to be removed via coagulation/flocculation, are important chloroform precursors. It is also suggested that hydrophobic organic intermediates with low molecular weight formed during chlorination may serve as the direct-acting mutagens.
- SourceAvailable from: ncbi.nlm.nih.govBacteriological reviews 07/1971; 35(2):171-205.
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ABSTRACT: In order to understand the effects of an immunomodulator in vivo, we performed time series analysis on mice given an aminopeptidase inhibitor, bestatin. This agent, which is known to be an immunopotentiator, caused peculiar oscillation of the activities of various hydrolytic enzymes in spleen. Autocorrelation curves obtained from serial data of each enzymatic activity revealed that sine curve-type oscillations are brought about in enzyme networks by this inhibitor. Judging from the pattern of the variations of enzymatic activities, it seems that metabolic homeostasis is strongly affected by this agent. The inhibitor probably initiated the homeostatic movements directly and secondarily caused extensive changes in the enzyme networks in vivo. This effect of bestatin may be useful in altering the pathological homeostasis (such as the one in autoimmune diseases) by affecting the dynamic equilibrium among the various components in the immunological system.Biochemistry international 11/1984; 9(4):405-11.
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ABSTRACT: Aqueous chlorination of humic acids results in the formation of compounds with direct-acting mutagenic activity in the Ames/Salmonella plate assay for tester strains TA98, TA100, TA1535, TA1537 and TA1538. The addition of a rat-liver microsomal fraction (S9) plus cofactors causes a substantial decrease of activity, the extent of which is tester strain dependent. The non-chlorinated humic acids are not mutagenic either in the presence or absence of S9. Formation of mutagenic activity and of total organic halogen (TOX) is linearly related to humic concentration in the range of 0.2-1.6 mg/ml total organic carbon (TOC), and to chlorine concentration in the range of 0.1-1.0 chlorine equivalents per mole of carbon. The mutagenic activity is due predominantly to non-volatile compounds. Mutagenic activity is also detectable, after sample concentration by lyophilization, upon chlorination at a humic acid level of 0.02 mg/ml TOC. The specific mutagenic activities (per mg TOX), and also the degree of chlorine incorporation into humic acid, at 0.02 mg/ml TOC are similar to those present after chlorination at 1 mg/ml TOC. Production of mutagens is greatly dependent on the chlorination pH, with a pattern of decreasing mutagenic activity with increasing pH. This order of activity can be at least partially explained by the alkali liability of the compounds. Chlorination of commercial humic acids is proposed as a model for examination of mutagen formation during water chlorination.Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 08/1983; 118(1-2):25-41. · 3.90 Impact Factor