Nuclease, deoxyribo-

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Study period:

19 June 1990 - 4 January 1991

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

This study is used as cross reference. Due to the similarity between enzymes, the same conclusion can be reached for deoxyribonuclease.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1991

Report date:

1991

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 E (Ready biodegradability: Modified OECD Screening Test)

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Active enzyme protein of Lipase, triacylglycerol (EC no. 232-619-9, CAS no. 9001-62-1, EC name: Lipase, triacylglycerol, Enzyme Class No.: 3.1.1.3)

Cas Number:

9001-62-1

Molecular formula:

Not applicable, see remarks

IUPAC Name:

Active enzyme protein of Lipase, triacylglycerol (EC no. 232-619-9, CAS no. 9001-62-1, EC name: Lipase, triacylglycerol, Enzyme Class No.: 3.1.1.3)

Constituent 2

Reference substance name:

Protein as a constituent of enzyme deriving from the fermentation or extraction process

Molecular formula:

Not available

IUPAC Name:

Protein as a constituent of enzyme deriving from the fermentation or extraction process

Constituent 3

Reference substance name:

Inorganic salts as a constituent of enzyme deriving from the fermentation or extraction process

Molecular formula:

Not available. See remarks.

IUPAC Name:

Inorganic salts as a constituent of enzyme deriving from the fermentation or extraction process

Constituent 4

Reference substance name:

Carbohydrates constituent of enzyme deriving from the fermentation or extraction process

Molecular formula:

Not available. See remarks.

IUPAC Name:

Carbohydrates constituent of enzyme deriving from the fermentation or extraction process

Constituent 5

Reference substance name:

Lipids as a constituent of enzyme deriving from the fermentation or extraction process

Molecular formula:

Not available. See remarks.

IUPAC Name:

Lipids as a constituent of enzyme deriving from the fermentation or extraction process

Test material form:

liquid

Details on test material:

- Lot/batch No.: LAJR 009-12
- Expiration date of the lot/batch: 1 August 1998

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge: The aeration stage of the HRC Limited sewage treatment plant treating predominantly domestic sewage.
- Preparation of inoculum for exposure: The aerated sample was filtered through a coarse filter paper (first approximately 200 mL discarded) and used on day of collection.
- Concentration of sludge: 0.5 mL of inoculum per litre dilution water

Duration of test (contact time):

28 d

Initial test substance concentration

Initial test substance concentration 1

Initial conc.:

250 mg/L

Based on:

test mat.

Initial test substance concentration 2

Initial conc.:

ca. 40 mg/L

Based on:

ThIC

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

TEST CONDITIONS
- Composition oftest medium: 1000 mL dilution water plus 1 mL nutrient solutions (a)-(f): (a) potassium dihydrogen phosphate: 8.5 g/L; di-potassium hydrogen phosphate: 21.75 g/L; di-sodium monohydrogen phosphate dihydrate: 33.4 g/L; ammonium chloride: 20 g/L), (b) magnesium sulphate heptahydrate (22.5 g/L), (c) calcium chloride (27.5 g/L), (d) iron(III)chloride hexahydrate (0.25 g/L), (e) Mangan sulphate tetrahydrate (39.9 mg/L), boric acid (57.2 mg/L), zinc sulphate heptahydrate (42.8 mg/L), ammonium molybdate tetrahydrate (36.85 mg/L) and (f) Yeast extract 15 mg/100 mL; plus 0.5 mL inoculum plus sufficient test substance. This is diluted to 2 litres with dilution water.
- Test temperature: 22 ± 1°C
- Continuous darkness: yes

TEST SYSTEM
- Number of culture flasks/concentration: 2 controls, 2 test substance and 2 reference substance
- Method used to create aerobic conditions: Aeration by magnetic stirrers and compressed air via narrow bore glass tubes.
- Measuring equipment: IONICS TC/TOC Analyser model 555.
- Test performed in open system: yes


SAMPLING
- Sampling frequency: day 0, 1,3, 7, 14, 21, 27 and 28
- Sampling method: Samples (ca. 20 mL) were withdrawn from each vessel and filtered through Sartorius Minisart NML, 0.45 µm disposable filters, discarding the first 10 mL.
- Sample storage before analysis: Samples were analysed directly


CONTROL AND BLANK SYSTEM
- Inoculum blank: inoculated test medium

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

% Degradation

% Degradation 1

Parameter:

% degradation (DOC removal)

Value:

44

Sampling time:

1 d

% Degradation 2

Key result

Parameter:

% degradation (DOC removal)

Value:

79

Sampling time:

3 d

% Degradation 3

Parameter:

% degradation (DOC removal)

Value:

92

Sampling time:

14 d

% Degradation 4

Key result

Parameter:

% degradation (DOC removal)

Value:

99

Sampling time:

28 d

BOD5 / COD results

Results with reference substance:

Sodium benzoate achieved 79 % degradation within 3 days and 95% degradation within 28 days.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Under the conditions of the test Lipase SP 400 was found to be readily biodegradable.

Executive summary:

Lipase SP 400 was assessed for ready biodegradability according to OECD Guideline 301E and EEC Directive 67/548 Annex V C.3 as published in 84/449/EEC, and in compliance with GLP.

SP 400 achieved 79% biodegradation within 3 days and 99% biodegradation within 28 days. The pass level of 70% was thus reached within 10 days of exceeding the 10% level.

The reference substance attained 95% biodegradation within 28 days, thereby confirmiung the suitability of the inoculum and the culture conditions.

In conclusion, SP 400 was found to be readily biodegradable under the conditions of the test.