L-isoleucine

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: screening test, other

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

Not specified

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1969

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

Activated sludge was exposed to chemicals, oxygen uptake was measured during 24h using the Warburg respirometer.

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

L-isoleucine

EC Number:

200-798-2

EC Name:

L-isoleucine

Cas Number:

73-32-5

Molecular formula:

C6H13NO2

IUPAC Name:

L-isoleucine

Test material form:

solid: crystalline

Study design

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): 3 sources of activated sludge
Source 1: Columbus, Ohio, municipal treatment plant, combined domestic and industrial wastewater
Source 2: Hilliard, Ohio, municipal treatment plant, domestic wastewater
Source 3: Brookside estates, Linworth, Ohio, residential wastewater
- Storage length: sample taken from aeration tank on day experiment started
- Preparation of inoculum for exposure: sludge suspension was blended for 10 sec and 20 ml was pipetted into the Warburg flasks
- Concentration of sludge: 2500 mg/L
- Water filtered: no

Duration of test (contact time):

24 h

Initial test substance concentration

Initial conc.:

500 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Test temperature: 20 °C

TEST SYSTEM
- Measuring equipment: Warburg respirometers, readings 0.5 to 5 h intervals

CONTROL AND BLANK SYSTEM
- Inoculum blank: control flask included with each run

Results and discussion

% Degradation

Key result

Parameter:

% degradation (O2 consumption)

Value:

14.8

Sampling time:

24 h

Applicant's summary and conclusion

Conclusions:

L-isoleucine showed good biodegradation within 24h, i.e. 14.8% of the initial test material was biodegraded within 24h. This study indicates that L-isoleucine has a potential to readily biodegrade.

Executive summary:

This study investigated the ability of activated sludges from 3 municipal waste treatment plants to oxidise amino acids. The activated sludge (concentration 2500 mg/L) was exposed to L-isoleucine at a concentration of 500 mg/L. The biodegradation was assessed during 24h by measurement of the O2 consumption using Warburg flasks.

The average biodegradation (as % of theoretical oxygen demand) over the 3 activated sludges was 14.8 %. Eventhough this study does not allow conclusion on ready biodegradability of L-isoleucine, the study clearly shows that rapid biodegradation can be expected since within 24h nearly 15 % of the substance is biodegraded.