Saccharomyces cerevisiae cell wall, extracted

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 5 January 2018 to 11 April 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 310 (Ready Biodegradability - CO2 in Sealed Vessels (Headspace Test)

Version / remarks:

Adopted March 23, 2006 and corrected September 26, 2014

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Saccharomyces cerevisiae, lysate

EC Number:

305-230-8

EC Name:

Saccharomyces cerevisiae, lysate

Cas Number:

94350-12-6

IUPAC Name:

Saccharomyces cerevisiae, lysate

Test material form:

solid: particulate/powder

Remarks:

light beige

Details on test material:

- Source and lot/batch No.of test material:
supplied by the sponsor, batch no. AC17F00560
- Expiration date of the lot/batch: February 2019
- Purity test date: 30 June 2017

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

The activated sludge used for this study was washed by centrifugation and the supernatant liquid phase was decanted.
The solid material was re-suspended in test water and centrifuged again. This procedure was done three times. An aliquot of the final sludge suspension was weighed, dried and the ratio of wet sludge to its dry weight was determined.
Based on this ratio, calculated aliquots of washed sludge suspension were mixed with test water corresponding to 4 g dry material per litre and aerated with CO2 free air overnight.

Initial test substance concentration

Initial conc.:

20.082 mg/L

Based on:

TOC

Remarks:

This corresponds to 43.92 mg/L test item based on an organic carbon content of 0.4272 mg carbon/ mg test item.

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: reconstituted test water
- Additional substrate: no
- Solubilising agent (type and concentration if used): no
- Test temperature: 20°C ± 1°C
- pH: 7.6
- pH adjusted: no
- CEC (meq/100 g): not reported
- Aeration of dilution water: the test water was aerated with CO2-free air prior to test start
- Suspended solids concentration: not reported
- Continuous darkness: yes

TEST SYSTEM
- Glass bottles with screw-caps and Teflon-coated septa (125 mL nominal, 128 mL total volume)
- 3 replicates per treatment and per sampling time. For the day 28, 5 replicates per treatment
For the day 2, only 2 replicates were analysed (damage of one flask)
- FT : test item (20.082 mg carbon/L) + activated sludge and test water
FB : Inoculum control with activated sludge and test water
Fc : procedure control with the reference item, sodium benzoate (19.976 mg Carbon/L), activated sludge and test water
Fi : Toxicity control (20.188 mg carbon/L) with test item , reference item (sodium benzoate), activated sludge and test water
Sodium hydroxyde solution 7M : two additional flasks with Sodium hydroxide solution (in CO2 free pure water) were prepared at each sampling date, except at day 2. The measured inorganic carbon content of the test flasks were corrected by this blank value. Additionally, two flasks with test water were measured at each sampling date to ensure that the water is nearly free of carbon.
- Sampling intervals : FT and FB: days 0, 2, 5, 9, 14, 16, 21, 28
FC and FI: days 0, 5, 14, 28

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

% Degradation

Key result

Parameter:

% degradation (CO2 evolution)

Value:

68.3

Sampling time:

16 d

Remarks on result:

other: readily biodegradable

Details on results:

The 10-day window started at day 2, when the degradation was 17.1%. At sampling at day 9 (within the 10-day window), the degradation was 66.8%. Therefore, the ready biodegradation criterion was passed.
The degree of biodegradation of the test item is 68.3% in 16 days. At the end of the test at day 28, the degradation was 56.4%.
In the toxicity control containing both, the test item and the reference item sodium benzoate, 70.0% biodegradation was noted within 14 days and 58.1% biodegradation after 28 days of incubation. Therefore the test item is not inhibitory.

BOD5 / COD results

Results with reference substance:

The reference item sodium benzoate was sufficiently degraded to 74.5% after 14 days and to 64.0% after 28 days of incubation.

Any other information on results incl. tables

TIC produced for the Test Item, Reference Item and Toxicity Control during the Test Period of 28 Day

 

Treatment	Carbon Content (mg/L)	Replicate	Day 0 2       5        9        14   16     18   28 ICcorrected(mg/L)^1
Na-Benzoate	19.976	1	0.00	-	15.88	-	14.04	-	-	13.45
		2	0.00	-	12.97	-	15.70	-	-	12.80
		3	0.00	-	12.26	-	**	-	-	11.60
		4	-	-	-	-	-	-	-	13.11
		5	-	-	-	-	-	-	-	12.91
		Mean	0.00		13.70		14.87			12.77
Saccharomyces cerevisiae, lysate	20.082	1	0.77	3.43	7.92	13.83	13.23	12.87	10.69	5.50
		2	1.00	3.43	6.48	13.04	14.03	13.75	11.28	10.00
		3	0.89	***	3.62	13.35	13.68	14.54	13.27	11.66
		4	-	-	-	-	-	-	-	13.78
		5	-	-	-	-	-	-	-	15.72
		Mean	0.89	3.43	6.00	13.41			11.75	11.33
Toxicity control	20.188	1	0.00	-	19.35	-	12.94	-	-	14.10
		2	0.00	-	13.93	-	14.27	-	-	9.53
		3	0.00	-	0.20	-	15.16	-	-	8.78
		4	-	-	-	-	-	-	-	16.33
		5	-	-	-	-	-	-	-	9.86
		Mean	0.00		11.16		14.12			11.72

 1 Corrected by the inoculum control

- Not applicable

** considered as outlier, value not used for calculation

*** no measurement possible due to damage of test flask

Biodegradation of Test Item, Reference Item and Toxicity Control during the Test Period of 28 Day

Treatment	Carbon Content (mg/L)	Replicate	Day 0       2   5     9       14   16       21 28 % biodegradation [net measured TIC/initial C *100]
Na-Benzoate	19.976	1	0.00	-	79.5	-	70.3	-	-	67.4
		2	0.00	-	64.9	-	78.6	-	-	64.1
		3	0.00	-	61.4	-	**	-	-	58.1
		4	-	-	-	-	-	-	-	65.6
		5	-	-	-	-	-	-	-	64.6
		Mean	0.00		68.6		74.5			64
Saccharomyces cerevisiae, lysate	20.082	1	3.8	17.1	39.4	68.9	65.9	64.1	53.2	27.4
		2	5.0	17.1	32.2	65.0	69.8	68.4	56.2	49.8
		3	4.4	***	18.0	66.5	68.1	72.4	66.1	58.1
		4	-	-	-	-	-	-	-	68.6
		5	-	-	-	-	-	-	-	78.3
		Mean	4.4	17.1	29.9	66.8	67.9	68.3	58.5	56.4
Toxicity control	20.188	1	0.0	-	95.8	-	64.1	-	-	69.9
		2	0.0	-	69.0	-	70.7	-	-	47.2
		3	0.0	-	1.0	-	75.1	-	-	43.5
		4	-	-	-	-	-	-	-	80.9
		5	-	-	-	-	-	-	-	48.9
		Mean	0.0		55.3		70.0			58.1

- Not applicable

** considered as outlier, value not used for calculation

*** no measurement possible due to damage of test flask

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The biodegradation of Saccharomyces cerevisiae, lysate estimated with the OECD 310 guideline, is 68.3% in 16 days and it satisfies the 10-day window.

Executive summary:

The substance Saccharomyces cerevisiae, lysate was tested for its ready biodegradability according to the OECD guideline No. 310 (CO2 headspace) and in compliance with the GLP.

The Inoculum was activated sludge microorganisms supplied by a municipal sewage treatment plant receiving domestic waste water.

The CO2 evolution resulting from the aerobic biodegradation of the test item by the inoculum was determined by measuring the inorganic carbon in the test flasks corrected by the control flasks. The extent of biodegradation was expressed as a percentage of the theoretical maximum IC production, based on the quantity of test substance initially added (as organic carbon). As a reference item, sodium benzoate was tested simultaneously under the same conditions as the test item, and functioned as a procedure control.

The test consisted of four groups :   

FT : test item (20.082 mg carbon/L)  + activated sludge and test water,

  FB : inoculum control with activated sludge and test water,

  Fc : procedure control with the reference item, sodium benzoate (19.976 mg Carbon/L), activated sludge and test water

  Fi : toxicity control (20.188 mg carbon/L) with test item, reference item (sodium benzoate), activated sludge and test water

The reference item sodium benzoate was sufficiently degraded to 74.5% after 14 days of incubation, thus confirming the suitability of the aerobic activated sludge inoculum used.

In the toxicity control containing both, the test item and the reference item sodium benzoate, 70.0% biodegradation was noted within 14 days. Therefore it can be assumed that the test item is not inhibitory to the aerobic activated sludge microorganisms.

The biodegradation of the test item reached 68.3% in 16 days.

The 10-day window started at day 2, when the degradation was 17.1%. At day 9 (within the 10-day window), the degradation was 66.8%. Therefore, the ready biodegradation criterion was passed.

In conclusion, Saccharomyces cerevisiae, lysate is designated as readily biodegradable, fulfilling the 10-day window.

This biodegradation test is classified as acceptable, and satisfies the guideline requirements of the OECD 310.