The construction industry makes a significant contribution to global CO₂ emissions. Material extraction, processing, and demolition account for most of its environmental impact. As a response, there is an increasing interest in developing and implementing innovative biomaterials that support a circular economy, such as mycelium-based composites. The mycelium is the network of hyphae of fungi. Mycelium-based composites are renewable and biodegradable biomaterials obtained by ceasing mycelial growth on organic substrates, including agricultural waste. Cultivating mycelium-based composites within molds, however, is often wasteful, especially if molds are not reusable or recyclable. Shaping mycelium-based composites using 3D printing can minimize mold waste while allowing intricate forms to be fabricated. In this research, we explore the use of waste cardboard as a substrate for cultivating mycelium-based composites and the development of extrudable mixtures and workflows for 3D-printing mycelium-based components. In this paper, existing research on the use of mycelium-based material in recent 3D printing efforts was reviewed. This review is followed by the MycoPrint experiments that we conducted, and we focus on the main challenges that we faced (i.e., contamination) and the ways in which we addressed them. The results of this research demonstrate the feasibility of using waste cardboard as a substrate for cultivating mycelia and the potential for developing extrudable mixtures and workflows for 3D-printing mycelium-based components.

Among the biotic constraints of common mushroom (Agaricus bisporus) production, bacterial blotch is considered the most important mushroom disease in terms of global prevalence and economic impact. Etiology and management of bacterial blotch has been a major concern since its original description in 1915. Although Pseudomonas tolaasii is thought to be the main causal agent, various Pseudomonas species, as well as organisms from other genera have been reported to cause blotch symptoms on mushroom caps. In this review, we provide an updated overview on the etiology, epidemiology, and management strategies of bacterial blotch disease. First, diversity of the causal agent(s) and utility of high throughput sequencing-based approaches in the precise characterization and identification of blotch pathogen(s) is explained. Further, due to the limited options for use of conventional pesticides in mushroom farms against blotch pathogen(s), we highlight the role of balanced threshold of relative humidity and temperature in mushroom farms to combat the disease in organic and conventional production. Additionally, we discuss the possibility of the use of biological control agents (either antagonistic mushroom-associated bacterial strains or bacteriophages) for blotch management as one of the sustainable approaches for 21^stcentury agriculture. Finally, we aim to elucidate the association of mushroom microbiome in cap development and productivity on one hand, and blotch incidence/outbreaks on the other hand.

Artificial lighting, primarily employed in crop production, can also be applied to the cultivation of edible mushrooms to enhance productivity and quality. While UV radiation has predominantly been investigated in post-harvest treatments for edible mushrooms, the utilization of different light wavelengths during the cultivation phase remains largely unexplored for many mushroom species. This study aimed to assess the impact of three different light wavelengths 450 nm (B), 610 nm (R), and a combination of these two wavelengths (R + B) on the productive characteristics and quality of Pleurotus ostreatus, cultivated using three straw-based commercial substrates. It was observed that, except for yield, artificial light influenced mushroom growth. Specifically, the application of R light appeared to promote mycelium growth, whereas B light contributed to increase the diameter of fruiting bodies. Additionally, the concentration of vitamin D₂ was higher under both B and R+B light treatments. Interestingly, the light treatments did not affect yield but impacted diameter and various chemical attributes such as EC, total soluble solids, and titratable acidity. In conclusion, exposure to different lighting affected Pleurotus ostreatus physiology and nutritional content.

Bacterial blotch is a complex of diseases, caused by Pseudomonas tolaasii and other Pseudomonas spp., whose growth may be influenced by other microorganisms associated with mushroom caps. The objectives of this work were to (i) compare methods for extracting DNA from mushroom caps to assess bacterial composition, and (ii) describe and quantify the composition of bacteria in and on symptomatic and asymptomatic mushroom caps. Symptomatic and asymptomatic mushrooms were collected at an organic farm in Pennsylvania and processed. Bacteria were removed from mushrooms by sonication to target surface-associated bacteria (washate), from whole mushrooms postsonication to target bacteria within or tightly adhering to the mushrooms (post-washate), or from whole macerated mushrooms to target all mushroom-associated bacteria in one sample (whole). Bacterial composition was determined through sequencing the V4 hypervariable region of the 16S rRNA gene on an Illumina MiSeq. Bacterial composition differed significantly based on mushroom health status and community removal method. Regardless of sampling approach, Proteobacteria and Bacteroidetes appeared as the most dominant phyla. In comparing the three extraction methods, higher Shannon diversity and Pielou’s evenness were observed for the washate and post-washate methods compared with whole mushroom sampling. Additionally, higher Shannon diversity, operational taxonomic unit richness, and Pielou’s evenness were found for the asymptomatic mushrooms when compared with symptomatic mushrooms. Pseudomonas spp. were overrepresented on mushroom surfaces (washate method), regardless of health status. This research made strides in describing the mushroom cap microbiome and established sampling methods that will allow researchers to target studies and isolation of specific bacterial taxa.