Fungal Toxins and Mushroom Poisoning Overview

Poisons

Any substances harmful to an organism.

Toxins

Harmful substances produced by an organism.

Mycotoxins

Produced by microfungi (Ascomycota).

Mushroom toxins

Produced mostly by Basidiomycota.

Poisonous mushroom

Toxins produced, symptoms, organs affected, incubation period, other notable features.

Mycotoxicosis

Caused by mycotoxins in humans and animals produced by Ascomycota (microfungi).

Mushroom poisoning syndrome

Caused by mushroom toxins which produce a variety of syndromes.

Aflatoxins

Produced by Aspergillus flavus in peanuts, corn, tree nuts, milk; acute poisoning may result in liver damage.

Ochratoxin

Produced by Aspergillus spp., Penicillium in fruits, coffee beans, dried fish; causes kidney damage.

Patulin

Produced by Penicillium expansum in rotten apples, apple juice; causes gastrointestinal issues and nausea.

Ergotamine

Produced by Claviceps purpurea in rye and other cereals; causes gangrene, extreme pain, hallucinations.

Amatoxin

Produced by Death caps (Amanita phalloides); causes severe liver damage.

Orellanine

Produced by Leprocybe subgenes of Cortinarius ore; causes nausea, vomiting, abdominal pain, diarrhea.

Orellanine

Produced by Cortinarius rubellus (Deadly Webcap); severely damages the renal tubuli in the kidneys.

Gyromitrin

Produced by False Morel (Gyromitra esculenta); causes gastrointestinal phase with abdominal pain, vomiting, headaches.

Ibotenic acid

Produced by Fly agaric (Amanita muscaria) and A. pantherina; causes nausea, vomiting, delirium, hallucinations.

Muscarine

Produced by Clitocybe and Inocybe; causes diarrhea, abdominal pain, and blurred vision.

Psilocybin

Produced by Psilocybe, Panaeolus and Inocybe; causes mind-altering experiences of euphoria and hallucinations.

Incubation period

The time interval between the mushroom meal and the occurrence of the first symptoms.

Heavy metals in mushrooms

Many species can accumulate cesium, cadmium, mercury, selenium, gold, arsenic, and others.

Chornobyl incident

Released massive amounts of radioactive cesium throughout Europe; some mushrooms exceeded safe limits afterward.

Pesticides

Edible mushrooms may be contaminated if collected from sprayed locations.

Raw edible mushrooms

Perfectly edible gourmet mushrooms may become highly poisonous if eaten raw, e.g., Morels.

Identifying mushrooms

Never eat mushrooms that you cannot identify 100%.

Morels

Perfectly edible gourmet mushrooms that may become highly poisonous if eaten raw.

How to Avoid Toxic Mushrooms

Never eat mushrooms that you cannot identify 100%. Don't eat raw field-collected mushrooms. Don't collect mushrooms that potentially contaminate sites. Don't eat old mushrooms. Only eat mushrooms from the grocery store.

Psychrophiles

Fungi that thrive in low temperatures, around 0-20 C, with peak growth rate occurring at about 10-15 C.

Mesophiles

Fungi that prefer temperatures of 10-45 C, with peak growth around 30-37 C, including most common fungi affecting humans and animals.

Thermophiles

Fungi that grow in temperatures of 40-70 C, with peak growth at 60 C, typically found in compost heaps, hot springs, or decaying organic matter.

Extreme Thermophiles

Fungi that thrive in temperatures of 65-100 C, with peak growth occurring near 90 C, rarely found in extreme environments like hydrothermal vents.

Substrate preparation

The process of preparing the material on which mushrooms will grow.

Composting (Phase 1)

The initial phase of mushroom cultivation where organic matter is decomposed.

Pasteurization and conditioning (Phase 2)

The process of heating the substrate to kill unwanted organisms and prepare it for mushroom growth.

Vegetative Growth Stage

The stage in mushroom cultivation where the mycelium grows and colonizes the substrate.

Spawn run (Phase 3)

The phase where the mycelium spreads throughout the substrate.

Case run (Phase 4)

The phase where the mushrooms begin to form and grow.

Reproductive (Phase 4)

The phase where mushrooms are harvested.

Post-harvest Management

The practices involved in handling mushrooms after they have been harvested.

Phase 1 Composting goals

Moisture 72-74%, aerobic conditions, loose structure for air movement, biological and thermal decomposition.

C:N ratio

The carbon to nitrogen ratio, which should be 22:1 for optimal composting.

pH

The acidity or alkalinity of the compost, which should be between 8-8.5.

Biological activity (40-60C)

The metabolic processes of fungi and bacteria that occur at these temperatures.

Chemical activity (60C+)

Processes such as non-enzymatic browning and caramelization that occur at higher temperatures.

Ammonification

The process by which organic matter is converted to ammonia (NH3).

Gypsum (CaSO4)

A mineral used in composting that helps to reduce pH and conserve nitrogen.

Benefits to using bunkers

Reduced space, time, more uniform temperature, more aerobic conditions, and reduced malodours emissions.

Pasteurization

The process of raising the temperature to around 60C to kill harmful organisms.

Conditioning

The process of lowering the temperature to the optimum range for beneficial mesophiles.

Role of Thermophilic Fungi in Phase 2

Dominated by Scytalidium, these fungi lower ammonia and improve the selectivity of compost.

Nutrients from Microbes in Compost

Microbial biomass before spawning constitutes 2% of compost dry weight.

Bacteria

1 x 10^11/g dry weight

Fungal and actinomycete mycelium

39.5 km/g dry weight

Spawn

Cereal grain colonized by fungus.

Initial growth to complete colonization

High CO2 3000 ppm to 20 000

Phase 3: Vegetative growth stage

Spawn run with successful colonization of the Phase 2 substrate by the mushroom fungus.

Phase 4: Case Run

Successful colonization of the casting layer by the mushroom fungus.

Casing

Layer over top of colonized material; pepe moss has to be sterilized before adding to colonized compost.

Conditions to stimulate vegetative growth

CO2 > 3,000 ppm, RH 95%

Pinning

Create conditions that stimulate the formation of primordia (pins).

Lower CO2 for pinning

1,000 ppm

Lower compost temperature for pinning

20C

Lower air temperature for pinning

17C

Minimum relative humidity for pinning

85% RH

Typical Casting Mixture

Peat/moss decayed plant matter plus something to increase density and/or water holding capacity plus agricultural lime to raise the pH to ca 7.4.

CAC

Compost Added at Casing

CI

Casing Inoculum

Oyster Mushroom Production Systems

Sawdust > bags sterilization bags > bottles sterilization bottles.

Temperature for spawn run

25 C

Light requirement for pinning

6 to 12 hours indirect light (fluorescent)

Shiitake Environmental Management

Carbon dioxide less than 1200 ppm, light during production, relative humidity 75 to 95%, growing temperature= 16 C.

Enoki Mushrooms

Enclosing in collar increases CO2 and low temps.

WHO Fungal Priority List

Global effort to prioritize fungal pathogens.

Mortality from cryptococcal meningitis

Estimated at 112,000 deaths per year.

Invasive aspergillosis in COPD

A severe fungal infection affecting patients with Chronic Obstructive Pulmonary Disease.

Invasive aspergillosis in ICU

A fungal infection that occurs in patients in Intensive Care Units.

Invasive aspergillosis in leukemia and lymphoma, and allogeneic HSCT

A fungal infection prevalent in patients with leukemia, lymphoma, and those undergoing allogeneic hematopoietic stem cell transplantation.

Invasive aspergillosis (lung cancer)

A fungal infection that can occur in patients diagnosed with lung cancer.

Chronic pulmonary aspergillosis

A long-term fungal infection affecting the lungs.

Fungi and Humans

Mammals are generally resistant to fungi compared to plants.

Human body temperature

The temperature of humans is 36-36C, which is less favorable for many fungi that prefer 25-30 C.

Human pH

Humans have an alkaline pH that contributes to resistance against fungi.

Immune system role

A complex immune system prevents the growth of fungal conidia when inhaled.

Opportunistic fungal diseases

Fungal diseases that occur due to factors like immunosuppression and underlying lung disease.

Human migratory patterns

Human movements have introduced different fungi into various regions.

Climate change and development

These factors can influence the prevalence and spread of fungal infections.

Facultative pathogens

Pathogens that can infect humans from the environment and have specific virulence.

Opportunistic infection

Infections that usually occur in specific environments and require host factors for disease progression.

Obligatory pathogens

Pathogens that are only found in mammals, such as Pneumocystis jirovecii.

Commensal

Organisms that use compounds from the host body without causing damage.

Colonization

Growth in the host body without invasion or host response, e.g., candida carriage in the gastrointestinal tract.

Infection

Multiplication in tissue without functional and structural damage.

Disease

Damage to host tissue resulting from fungal growth.

Risk factors for fungal infections

Factors that increase the likelihood of fungal infections, including antimicrobial agents and immunosuppression.

Diagnostic Methods

Techniques used to identify fungal infections, including microscopy and culture.

Galactomannan

A test used for the identification of Aspergillus species.

C. albicans

The most common Candida species in the region, usually susceptible to antifungal antibiotics.

C. auris

A new multi-drug-resistant species of Candida.

C. parapsilosis

A high-priority Candida species often related to line infections and a biofilm producer.

C. glabrata

A high-priority Candida species that shows reduced susceptibility or resistance to fluconazole.

Aspergillus fumigatus complex

A group of Aspergillus species with varying resistance prevalence based on geographic area.