Mannanase, endo-1,4-β-

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

12 September 2000 - 7 February 2001

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Version / remarks:

1992

Deviations:

no

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Haddington Municipal Sewage Treatment Works (UK)
- Preparation of inoculum for exposure: The activated sludge was well mixed prior to sampling for solids content determination. The solids content of the sludge was determined as 3.6g solids per litre sludge. The sludge was then allowed to settle for at least 30 min prior to a sample of the supernatant being withdrawn for use as the test inocolum.

Duration of test (contact time):

28 d

Initial conc.:

20 mg/L

Based on:

DOC

Initial conc.:

389.5 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: Mineral Medium: 10 mL phosphate buffer (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: 0.51 g/L) plus 1 mL magnesium sulphate heptahydrate (22.5 g/L) plus 1 mL calcium chloride dihydrate (36.4 g/L) plus 1 mL iron(III)chloride hexahydrate (0.25 g/L) was diluted in deionised water to a final volume of 1 litre.
- Test temperature: 20 to 22°C
- pH: 7.4 to 8.0
- Suspended solids concentration: 36 mg/L

TEST SYSTEM
A totally sealed system was constructed and supplied on a positive pressure basis by CO2 free air. CO2 was removed by passing through self-indicating soda lime granules contained in a 2 litre capacity glass aspirator. The CO2 free air was then passed through the bioreactor set-ups.
- Number of culture flasks/concentration: 2 with test material, 2 controls, 1 reference material, 1 cytotoxicity control
- Details of trap for CO2: Each bioreactor was connected to three traps, each trap containing 100 mL 0.0125M Ba(OH)2.

CONTROL AND BLANK SYSTEM
- Inoculum blank: inoculated Mineral Medium alone
- Toxicity control: Test substance plus reference substance
- Reference substance: Sodium benzoate - 20 mg DOC/L

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (CO2 evolution)

Value:

14

Sampling time:

2 d

Parameter:

% degradation (CO2 evolution)

Value:

55.1

Sampling time:

7 d

Key result

Parameter:

% degradation (CO2 evolution)

Value:

63

Sampling time:

9 d

Parameter:

% degradation (CO2 evolution)

Value:

68.4

Sampling time:

12 d

Parameter:

% degradation (CO2 evolution)

Value:

73.7

Sampling time:

29 d

Results with reference substance:

The reference material was readily biodegradable. 62.5% biodegradation was achieved after 7 days and 73.4% biodegradation was achieved over the 29 day test period.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Mannnanase, batch PPE6432 was found to be readily biodegradable in the 'Ready Biodegradability, Modified Sturm Test' (OECD 301B).

Executive summary:

Mannanase, PPE6432 was tested for ready biodegradation by means of a 28-Day Modified Sturm Test. The study was designed to be consistent with OECD Test Guideline 301B (1992) and EU guideline C4-C, and performed in accordance with GLP.

A total of six bioreactors were used, two vessels each for the test material and control, one each for the reference material and toxicity control. Mannanase, PPE6432 was introduced to the test system at 20 mg Dissolved Organic Carbon/L. Mannanase, PPE6432 showed the greater part of biodegradation between Day 2 and 7, increasing from 14.0 to 55.1%. Mannanase, PPE 6432 reached 38.4% within 5 days and 63.0% biodegradation within 9 days. The total cumulative biodegradation achieved by Day 29 was as follows:  Reference material (Sodium Benzoate) and Test Material (Mannanase, PPE 6432) % Biodegradation of 73.4 and 73.7, respectively. Mannanase, PPE6432 was readily biodegradable under the conditions of this test, as the 60% biodegradation value was met. There was no inhibitory effect on the activity of the microbial inoculum by the test material as the CO₂ production in the toxicity control was greater than in the separate test and reference material vessels. The total control CO₂ production over the test period was 35.1 mg CO₂ (from a 2 liter volume). The test system and results obtained were considered to be valid.

In conclusion, Mannnanase, batch PPE6432 was found to be readily biodegradable in the 'Ready Biodegradability, Modified Sturm Test' (OECD 301B).

Description of key information

Mannanase was found to be readily biodegradable in the 'Ready Biodegradability, Modified Sturm Test' (OECD 301B).

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

Mannanase, PPE6432 was tested for ready biodegradation by means of a 28 Day Modified Sturm Test.

The study was designed to be consistent with OECD Test Guideline 301B and EU guideline C4-C, and performed in accordance with GLP.

Mannanase, PPE6432 was introduced to the test system at 20 mg Dissolved Organic Carbon/L. Mannanase, PPE6432 showed the greater part of biodegradation between Day 2 and 7, increasing from 14.0 to 55.1%. Mannanase, PPE 6432 reached 38.4% within 5 days and 63.0% biodegradation within 9 days.

The total cumulative biodegradation achieved by Day 28 was as follows: 

	Reference material (Sodium Benzoate)	Test Material (Mannanase, PPE 6432)
% Biodegradation	73.4	73.7

 

Mannanase, PPE6432 was readily biodegradable under the conditions of this test, as the 60% biodegradation value was met.

There was no inhibitory effect on the activity of the microbial inoculum by the test material as the CO₂ production in the toxicity control was greater than in the separate test and reference material vessels. The total control CO₂ production over the test period was 35.1 mg CO₂ (from a 2 liter volume).

 

Mannanase, PPE6432 was readily biodegradable under the conditions of this test.