17-acetoxy-1β,2β-methanopegna-4,6-diene-3,20-dione

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

toxicity to microorganisms, other

Type of information:

experimental study

Adequacy of study:

key study

Study period:

16. Apr - 17. Aug 1998

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: DIN 38412, L8 (Pseudomonas - Zellvermehrungshemmtest)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

nutrient solutions:
Solution 1: 10.0 g sodium nitrate, 2.4 g dipotassium hydrogen phosphate, 1.2 g potassium dihydrogenphosphate, 1.0 g yeast extract added to 500 mL distilled water
Solution 2: same as solution 1, excluding yeast extract
Solution 3: 40 g D (+) glucose-monohydrate added to 500 ml distilled water
Solution 4: 4 g magnesiumsulphate-heptahydrate, 0.01 g iron citrate, added to 1,000 mL distilled water

Stock solution:
- 112.5 mg test substance dissolved in 1000 mL double distilled water.
- Stirred for 24 hours at room temperature
- This solution was used for the highest concentration.
- Subsequently, this stock solution was filtered.
Test solutions:
- Test concentration separation factor: 2
- 80 mL of the respective solutions were poured into the test vessels.

Test organisms (species):

Pseudomonas putida

Details on inoculum:

- Laboratory culture: Pseudomonas putida
- Name and location of sewage treatment plant where inoculum was collected: "Deutschen Sammlung für Mikroorganismen, Braunschweig"
- Method of cultivation: Cultivated on slant agar containing a nutrient solution at approximately 25 °C. During culturing the microorganisms were transferred weekly
- Preparation of inoculum for exposure:
The microorganisms for preculture:
- From seven-day-old stock
- approximately 7 hours before the start of incubation.
Pre-culture nutrient solution:
- 25 ml of solution 1, 25 ml of solution 3 and 50 ml of solution 4 (see details on test solutions) in 900 ml of sterile distilled water.
- The preculture had a turbidity of 0.07 absorbance units (corresponding to approximately TE/F 10, spectrophotometer)
-Subsequently incubated for 7 hours at room temperature (0.437 absorbance units) -Dilution of the preculture to 0.229 absorbance units (equivalent to approximately TE/F 50).

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

16 h

Details on test conditions:

TEST SYSTEM
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2 (blank control)

Preparation of the test solutions and addition of the inoculum:
- 2.5 mL of nutrient solution 2, 2.5 mL of nutrient solution 3, and 5 mL of nutrient solution 4 were added to the 80 mL of test compound solutions and 10 mL of the inoculum.

Reference substance (positive control):

no

Key result

Duration:

16 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Remarks on result:

not determinable

Remarks:

The test substance produced no inhibitory effects as a saturated aqueous solution.

Measurement of the turbidity:
The turbidity of the test concentrations, the control and the test solutions without inoculum were measured after 16 hours. All measurements were performed at a wavelength of 436 nm (Spectral photometer) and the absorbance was determined in TE/F units according to DIN 38404.
Inhibition percentage was calculated according to the following formula:

inhibition [%] = ((TE/F control [16 h] - TE/F test concentration [16 h]) / TE/F control [16 h]) *100

Result:

Turbidity and grawth inhibition of the test and contral solutions after 16 hours

Concentration (Stock solution, saturated)	TE/F +/- Std. div.	growth inhibition [%]
			Control	364 +/- 24	0
1:8 diluted, filtered	369 +/- 18	-1.37
1:4 diluted, filtered	391 +/- 9	-7.42
1:2 diluted, filtered	389 +/- 12	-6.87
not diluted, filtered	384 +/- 3	-5.49
not diluted, not filtered	385 +/- 19	-5.77

The turbidity of the contral at 0 hours as weil as of all blank solutions after 16 hours was < 1 TE/F. The parallel test vessels showed no relevant variation.

Validity criteria fulfilled:

not applicable

Conclusions:

The slight reduction in growth was not concentration dependent and is not considered relevant. No inhibitory effect of the test substance on the growth of Pseudomonas putida up to the solubility limit of about 1 mg/L was observed. Therefore, the test solution is not toxic to Pseudomonas putida up to the solubility limit.

Executive summary:

The study was perfomred to assess the toxicity of the test substance to bacteria. The study was conducted in accordance with the DIN 38412 L8. The slight reduction in growth was not concentration dependent and is not considered relevant. No inhibitory effect of the test substance on the growth of Pseudomonas putida up to the solubility limit of about 1 mg/L (according to acute toxicity to fish, Länge, 1998) was observed. Therefore, the test solution is not toxic to Pseudomonas putida up to the solubility limit.

Description of key information

The study was performed to assess the toxicity of the test substance to bacteria. The study was conducted in accordance with the DIN 38412 L8. The slight reduction in growth was not concentration dependent and is not considered relevant. No inhibitory effect of the test substance on the growth of Pseudomonas putida up to the solubility limit of about 1 mg/L (according to acute toxicity to fish, Länge, 1998) was observed. Therefore, the test solution is not toxic to Pseudomonas putida up to the solubility limit.