Saccharomyces cerevisiae cell wall, extracted

Toxicity to soil microorganisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to soil microorganisms

Type of information:

other: Review

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Qualifier:

no guideline required

Principles of method if other than guideline:

Not applicable

GLP compliance:

not specified

Key result

Dose descriptor:

other: none

Conc. based on:

not specified

Remarks:

Not applicable

Basis for effect:

other: Not applicable

Remarks on result:

other: Review. Quantitative result was not determined.

Executive summary:

The cell wall of Saccharomyces cerevisiae is an elastic structure that provides osmotic and physical protection and determines the shape of the cell. The inner layer of the wall is largely responsible for the mechanical strength of the wall and also provides the attachment sites for the proteins that form the outer layer of the wall. Here we find among others the sexual agglutinins and the flocculins. The outer protein layer also limits the permeability of the cell wall, thus shielding the plasma membrane from attack by foreign enzymes and membrane-perturbing compounds. The main features of the molecular organization of the yeast cell wall are now known. Importantly, the molecular composition and organization of the cell wall may vary considerably. For example, the incorporation of many cell wall proteins is temporally and spatially controlled and depends strongly on environmental conditions. Similarly, the formation of specific cell wall protein polysaccharide complexes is strongly affected by external conditions. This points to a tight regulation of cell wall construction. Indeed, all five mitogen-activated protein kinase pathways in bakers’ yeast affect the cell wall, and additional cell wall-related signaling routes have been identified. Finally, some potential targets for new antifungal compounds related to cell wall construction are discussed.

Reference 2

Endpoint:

toxicity to soil microorganisms

Type of information:

other: Review

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Qualifier:

no guideline required

Principles of method if other than guideline:

Not applicable

GLP compliance:

not specified

Key result

Dose descriptor:

other: None

Conc. based on:

not specified

Remarks:

Not applicable

Basis for effect:

other: Not applicable

Remarks on result:

other: Review. Quantitative result was not determined.

Executive summary:

Microbes express many competitive phenotypes in the presence of others; exploitative phenotypes include metabolic changes that increase growth rates or molecule secretion to harvest nutrients, while interference competition occurs through antimicrobial secretions or contact-dependent killing.
Microbial competition is common, although evidence suggests that, in many environments, interspecies interactions are weak.
Competition is expected on first encounter, but can be reduced over time through competitive exclusion, or niche partitioning via resource or spatial separation, leading to communities with a reduced local diversity of strains and species that can nevertheless coexist stably.
Many complementary methods exist for studying microbial communities. Combining them to analyse a simple community would reveal a more complete picture.
Microbes are typically surrounded by different strains and species with whom they compete for scarce nutrients and limited space. Given such challenging living conditions, microbes have evolved many phenotypes with which they can outcompete and displace their neighbours: secretions to harvest resources, loss of costly genes whose products can be obtained from others, stabbing and poisoning neighbouring cells, or colonising spaces while preventing others from doing so. These competitive phenotypes appear to be common, although evidence suggests that, over time, competition dies down locally, often leading to stable coexistence of genetically distinct lineages. Nevertheless, the selective forces acting on competition and the resulting evolutionary fates of the different players depend on ecological conditions in a way that is not yet well understood. Here, we highlight open questions and theoretical predictions of the long-term dynamics of competition that remain to be tested. Establishing a clearer understanding of microbial competition will allow us to better predict the behaviour of microbes, and to control and manipulate microbial communities for industrial, environmental, and medical purposes.

Reference 3

Endpoint:

toxicity to soil microorganisms

Type of information:

other: Risk assessment

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Qualifier:

no guideline required

Principles of method if other than guideline:

Not applicable

GLP compliance:

not specified

Key result

Dose descriptor:

other: None

Effect conc.:

other: None

Conc. based on:

other: Not applicable

Basis for effect:

other: Not applicable

Remarks on result:

other: Review. Quantitative result was not determined.

Conclusions:

Yeast Saccharomyces cerevisiae is ubiquitous in nature and naturally occuring in all environmental compartments and animals. soil organisms are continuously and naturally exposed to Saccharomyces cerevisiae. No toxicity of yeast and yeast extract is expected in all environmental comparments.

Executive summary:

Yeast Saccharomyces cerevisiae is ubiquitous in nature and naturally occuring in all environmental compartments and animals. soil organisms are continuously and naturally exposed to Saccharomyces cerevisiae. No toxicity of yeast and yeast extract is expected in all environmental comparments.

Additional information

Saccharomyces cerevisiae which is present worldwide in soils and on different types of crops, on leaves and on fruits, has an extensive history of use in the area of food processing. Also known as Baker's Yeast or Brewer's Yeast. This organism has been used for centuries as leavening for bread and as a fermenter of alcoholic beverages. Saccharomyces cerevisiae is not a plant or animal pathogen; despite the fact that Saccharomyces cerevisiae is ubiquitous in nature, it has not been found to be associated with disease conditions in plants or animals [US EPA 1997].
When a Saccharomyces cerevisiae cell dies, an autolysis occurs naturally, and the lysate fraction of the cell is released and progressively degraded. is not a living microorganism, but an inert derivative from a strain of Saccharomyces cerevisiae (yeast cell walls).
The cell wall of Saccharomyces cerevisiae is an elastic structure that provides osmotic and physical protection and determines the shape of the cell. Cell wall macromolecules in Saccharomyces cerevisiae are the following [Klis 2002]: Mannoproteins 35-40 %, L1,6-Glucan 5-10 %, L1,3-Glucan 50-55 %, Chitin 1- 2 %.
Microbes grow in challenging environments where scarce resources must be shared with many other strains and species. Under these conditions, microbes have evolved many competitive strategies, including rapid growth to take up resources, direct aggression to eliminate or displace others, or alternative metabolisms that benefit from and exploit the presence of competitors. While this may sound like a highly aggressive microbial world, evidence suggests that competition often drops over time, leading to stable equilibria involving weak interactions between strains that have either eliminated their competitors or partitioned the available niches and space [Ghoul 2016].
However, in the present case, on the one hand, the active principle does not consist of living Saccharomyces cerevisiae, but yeast cell walls which have thus lost the specific physiological properties of yeast, and in particular its ability to compete with other microorganisms. In another hand, when a Saccharomyces cerevisiae cell naturally dies, an autolysis occurs naturally, and yeast cell walls are released and progressively degraded.
So that where Saccharomyces cerevisiae is present in the environment, cell walls of the yeast (carbohydrates, fats and proteins, mannans, glucans and some ions), are also present which have lost the intrinsic physiological properties of the yeast (multiplication ...).
Under these conditions, interactions between the yeast cell walls and soil microorganisms are unlikely to occur, other than potentially providing nutrients. And, given all of this data, it does not seem toxicity is expected on soil microorganisms.