The 16th ISMS congress and the 17th NAMC in Miami Beach

In this article, I have summarized the presentations of the first two keynote speakers at the ISMS in Miami, USA. These keynote presentations were interesting and of major importance for the mushroom world. In addition, I have summarized the break-out session that covered the topic of compost technology. This session about compost production and processes was particularly interesting because of the general discussion at the end encountering the challenges for the near future.

Bioactive compounds in Agaricus

The first keynote speaker of the ISMS-meeting was Dr. Robert Beelman from Pennsylvania State University, USA, who gave an outstanding presentation about bioactive compounds in White button mushroom (Agaricus bisporus) that are of nutritional, medicinal and biological importance.

He laid out that White button mushrooms comprises 32% of world mushroom production, but that this fungus is considered to be of minor importance according to its nutrition and medicinal value. Species including shiitake and oyster mushroom, good for 25% and 14% of world production respectively, are considered to have higher nutritional and medicinal value than Agaricus bisporus.

However, White button mushrooms are a valuable source of nutrition, good for 10% of the daily value. Dr. Beelman illustrated this by showing that they are a good source of containing the same proteins as shiitake and oyster mushrooms. In addition, White button mushrooms contain fibers and ergosterol, a precusor of vitamin D. 

Subsequently, Dr. Beelman showed that the amount of certain nutrients in mushrooms can be increased. For instance, potassium and selenium content in White button mushrooms can be raised by addition of these nutrients to the compost.

Particularly, an increased selenium content in edible mushrooms is of value, because it has been shown that selenium reduces cancer mortality. Dr. Beelman showed that in an experiment with test persons who received 200 ug/day, compared to persons who received placebo’s, lung, colorectal and prostate cancer was reduced with 50%. Cancer reduction in mice was obtained after a diet of mushrooms with increased content of selenium. These results offer great perspective for the mushroom world in developing a disease preventing food source.

Trait diversity in wild Agaricus

At the second day of the meeting Dr. Rick Kerrigan from Sylvan, Pennsylvania, USA, opened the day with his excellent keynote presentation on trait diversity in wild Agaricus bisporus. 

Dr. Kerrigan laid out that White button mushroom is the most profitable crop in the world and research on this mushroom started early. Beatrix Potter, well-known for work on Peter Rabbit, started off research on edible mushrooms. However, being a woman scientist in that time, she was not allowed to publish any of her work, or to present it to the international world.

In his talk, Dr. Kerrigan showed that humans started to exploit White button mushroom as a nutrient source since the last ice age, 10,000 years ago. In the twentieth century, interest started to grow in the best culture, and the colour of the cap became an economically important characteristic. Breeding of White button mushrooms started to develop.

To overcome obstacles in the development of new strains, Dr. Kerrigan developed the Agaricus Resource Program. The aim of this program was to understand, study and exploit the White button mushroom. Within this program, considerable progress has been made: 261 strains are acquired, 40 papers have been published and different populations all over the world have been detected. Moreover, questions about sexual reproduction have been addressed enabling the development of new strains. Currently, the development of White button strains with resistance to the major diseases Verticillium fungicola and Trichoderma aggressivum through breeding is underway.

Dr. Kerrigan laid out that a considerable group of pioneer researchers from all over the word had done the hard work in the twentieth century. Nowadays, the second wave of researchers develop new strains by the use of molecular tools.

However, the number of research groups working on mushroom breeding has decreased considerable. Therefore, Dr. Kerrigan wondered whether the current researchers will be followed up by young researchers in the future. There is a strong urge for a third wave of research to meet the challenges in mushroom production. Still, browning of the caps of the White button mushrooms is a major problem to be tackled. We still miss strains that are resistant against Verticillium fungicola and Trichoderma aggressivum. There is a strong urge for better understanding of Virus X. And for facilitating the development of new strains, Dr. Kerrigan addressed that cultures of White button mushroom from the southern hemisphere are still missing.

Compost technology

One of the twelve break-out sessions dealt with compost technology. Dr. Jacqueline Baar from the Mushroom Unit of Applied Plant Research, The Netherlands, was chairing this session. Seven papers were addressed in this session about compost and the processes around composting. 

A major problem in the United States and Canada was addressed by Dr. Greg Duns from Air Chem and Consulting, Ontario, and Prof. Dan Rinker, University of Guelph, Canada. Dr. Duns discussed the release of substrate odours during composting. He showed that a considerable amount of smells are released during the composting, and to what extent these odours are experienced as unpleasant.

The participants in the session discussed what the possible solutions are to reduce the unpleasant smells. A way to solve this problem could be to move to remote areas where people do not live. Another solution could be changing the composting process from open air or half open bunkers to closed systems like in The Netherlands. During the discussion, someone also suggested to replace the compost by different substrates to avoid composting. Although, the problems have been solved in The Netherlands and compost odours stay under the concentrations required by the Dutch law, a major challenge for Canada and the United States is to solve their odour problems during composting.

Dr. Shakhar Sharma from the University of Belfast, Northern Ireland, gave two presentations in this session. In one presentation, he showed how the Near Infrared methodology can be applied to describe the chemical composition of nutrients. In the other presentation, he showed to what extent the quality of the compost in Northern Ireland has increased over the last decades. This has resulted in a generally higher yield.

Two presentations in this session were focused on sustainability. Dr. Baar gave a presentation about the development of organic compost for White button mushroom. The Dutch Ministry of Agriculture has the aim to increase organically grown crops, including mushrooms, with 5% in 2005. To meet this aim and to enable the growth of organic mushrooms, organic compost is needed at a larger scale.

However, there is a lack of organic straw and horse manure. Therefore, this study focused on possible alternative compounds to produce mushrooms. Reed (Phragmites australis) and organic pig manure were used in experiment. The results showed that pig manure contained too much nitrogen for a standard composting process. Moreover, the yields of mushrooms were relative low on the pig manure and reed. Adjustment of the composting processes and a search for other alternative compounds is needed in the future, as was laid out by Dr. Baar.

Prof. Dan Rinker gave a nice presentation on the degradation of pesticides during mushroom composting and production. He showed that pesticides in the water added during wetting can contain a number of pesticides. Fortunately, the majority of pesticides is degraded during composting. The remaining two pesticides that do not completely break down during the composting process, were not found in White button mushrooms. Therefore, Dr. Rinker had a good news story, showing that not any pesticides occur in White button mushrooms.