Laccase

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

January 25, 1996 - April 15, 1996

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 100 mg dry material/L
- Sampling method: At the start and the end of the limit test, duplicate 5 mL samples were taken from the control and the limit concentration, both without algae. The samples were placed in glass scintillatioon flasks and immediately placed in a freezer.
- Sample storage conditions before analysis: in a freezer

Vehicle:

no

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

TEST ORGANISM
- Common name: green alga
- Strain: Selenastrum capricornotum
- Source (laboratory, culture collection): American Culture Collection, c/o Sales Department, 12301 Parklawn Drive, Rockville, Maryland 20852, USA

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Test temperature:

23 +/- 1°C

pH:

7.7-8.2

Nominal and measured concentrations:

nominal: 100 mg dry matter/L
measured: start of the test: 89-91 mg dry matter/L
measured: end of the test: 57-59 mg dry matter/L

Details on test conditions:

TEST SYSTEM
- Test vessel: conical flask
- Type (delete if not applicable): closed
- Size, fill volume: 200 ml, 100ml
- Initial cells density: 1*10^4 cells/mL
- No. of vessels per concentration (replicates): 6
- No. of vessels per control (replicates): 6


OTHER TEST CONDITIONS
- Light intensity and quality: fluorescent lamps 60-120 µmol/s/m2

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : growth parameters (inoculum viability, growth rate and growth yield); morphology of algae was examined visually at the start and the end of the test.
- Determination of cell concentrations: electronic particle counter

Reference substance (positive control):

no

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

other: dry matter

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

other: dry matter

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

other: dry material

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

< 100 mg/L

Nominal / measured:

nominal

Conc. based on:

other: dry matter

Basis for effect:

biomass

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 2.68 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

act. ingr.

Remarks:

active enzyme protein

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 74 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

other: dry matter

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

< 74 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

other: dry matter

Basis for effect:

other: growth rate and biomass

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

< 2.68 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

act. ingr.

Remarks:

active enzyme protein

Basis for effect:

other: growth rate and biomass

Validity criteria fulfilled:

yes

Remarks:

sufficient control growth rate and limited increase of the test medium pH

Conclusions:

Exposure of the freshwater algae Selenastrum capricornutum to 74 mg dry material/L did not result in inhibition of the growth rate, but affected yield. The algal growth was inhibited 23% following the exposure of alga to the test substance at a concentration of 74 mg dry material/L. Due to the low toxicity of the test material, the 72-hour EC50 value of the substance was unable to be calculated. Therefore the following values were assumed:
The 72-hour EC50 value for the test substance to freshwater algae Selenastrum capricornutum was determined to be >74 mg dry material/L corresponding to >2.68 mg aep/L.
The no-observed effect concentration (NOEC) was less than 74 mg dry material/L corresponding to less than 2.68 mg aep/L.

Executive summary:

The toxicity of laccase to the fresh water algae Selenastrum capricornutum was determined in a growth inhibition limit test according to the OECD and EU guidelines and in compliance with GLP.

The limit concentration of laccase tested was 100 mg dry material/L and a control with algae only. The test included quantification of the enzyme (laccase) activity at the start and the end of the test. Verification of test concentrations was performed based on enzyme activity. The amount of measured enzyme (LACU/g) was then converted to mg dry matter/L in order to calculate the achieved measured concentrations.

The algal growth was determined by electronic particle counting. The growth parameters of the cultures (i.e. growth rate, inoculum and yield) were calculated using a paramtric model.

Measured concentrations ranged from 89 -90 % of nominal at 0 hours and from 57 -59% at 72 hours. The average percentage present during the test was 74%.

The following results were obtained:

- The limit concentration, being 100 mg dry material per litre did not inhibit growth rate, but affected the yield.

- The lkimit concentration inhibited the algal growth (calculated as area under the growth curves) by 23%.

- It was concluded that ErC50 and the EbC50 values for laccase are both >100 mg dry material/L (nominal) or 74 mg dry material/L (measured) or 2.68 mg active enzyme protien/L (measured).

- NOEC was assessed to be <100 mg dry material/L (nominal) or < 74 mg dry material/L (measured) or < 2.68 mg active enzyme protein/L (measured).

Description of key information

Exposure of the freshwater algae Selenastrum capricornutum to 74 mg dry material/L did not result in inhibition of the growth rate, but affected yield. The algal growth was inhibited 23% following the exposure of alga to the test substance at a concentration of 74 mg dry material/L. Due to the low toxicity of the test material, the 72-hour EC50 value of the substance was unable to be calculated. Therefore the following values were assumed: The 72-hour EC50 value for the test substance to freshwater algae Selenastrum capricornutum was determined to be >74 mg dry material/L corresponding to 2.68 > mg aep/L. The no-observed effect concentration (NOEC) was less than 74 mg dry material/L corresponding to less than 2.68 mg aep/L.

Additional information

The toxicity of laccase to the fresh water algae Selenastrum capricornutum was determined in a growth inhibition limit test according to the OECD and EU guidelines and in compliance with GLP.

The limit concentration of laccase tested was 100 mg dry material/L and a control with algae only. The test included quantification of the enzyme (laccase) activity at the start and the end of the test. Verification of test concentrations was performed based on enzyme activity. The amount of measured enzyme (LACU/g) was then converted to mg dry matter/L in order to calculate the achieved measured concentrations.

The algal growth was determined by electronic particle counting. The growth parameters of the cultures (i.e. growth rate, inoculum and yield) were calculated using a paramtric model.

Measured concentrations ranged from 89 -90 % of nominal at 0 hours and from 57 -59% at 72 hours. The average percentage present during the test was 74%.

The following results were obtained:

- The limit concentration, being 100 mg dry material/L did not inhibit growth rate, but affected the yield.

- The limit concentration inhibited the algal growth (calculated as area under the growth curves) by 23%.

- It was concluded that ErC50 and the EbC50 values for laccase are both >100 mg dry material/L (nominal) or 74 mg dry material/L (measured) or 2.68 mg active enzyme protien/L (measured).

- NOEC was assessed to be <100 mg dry material/L (nominal) or <74 mg dry material/L (measured) or <2.68 mg active enzyme protein/L (measured).