Sunday, May 19, 2024

Zombie cells in the sea: Viruses keep the most common marine bacteria in check

MAX PLANCK INSTITUTE FOR MARINE MICROBIOLOGY

The ocean waters surrounding the German island of Helgoland provide an ideal setting to study spring algae blooms, a focus of research at the Max Planck Institute for Marine Microbiology since 2009. In a previous study, the Max Planck scientists observed a group of bacteria called SAR11 to grow particularly fast during these blooms. However, despite their high growth rates, the abundance of SAR11 decreased by roughly 90% over five days. This suggested that the cells were quickly decimated by predators and/or viral infections. Now, the Max Planck researchers investigated what exactly lies behind this phenomenon.

Finding the phages infecting SAR11

“We wanted to find out if the low numbers of SAR11 were caused by phages, that is viruses that specifically infect bacteria”, explains Jan Brüwer, who conducted the study as part of his doctoral thesis. “Answering this seemingly simple question was methodologically very challenging”.

How does phage infection work? Phages infect bacteria by introducing their genetic material into them. Once there, it replicates, and utilizes the bacterial ribosomes to produce the proteins it needs. Researchers from Bremen used a technology that enabled them to “follow” the phage’s genetic material inside the cell. “We can stain the specific phage genes and then see them under the microscope. Since we can also stain the genetic material of SAR11, we can simultaneously detect phage-infected SAR11 cells”, explains Jan Brüwer.

While this might seem straightforward, the low brightness and small size of the phage genes made it challenging for researches to detect them. Nonetheless, thousands of microscope images were successfully analyzed, bringing some exciting news.

“We saw that SAR11 bacteria are under massive attack by phages”, says Jan Brüwer. “During periods of rapid growth, such as those associated with spring algae blooms, nearly 20% of the cells were infected, which explains the low cell numbers. So, phages are the missing link explaining this mystery.”

Zombie cells: A global phenomenon

To the surprise of the scientists, the images revealed even more. "We discovered that some of the phage-infected SAR11 cells no longer contained ribosomes. These cells are probably in a transitional state between life and death, thus we called them 'zombie' cells”, Brüwer explains.

Zombie cells represent a novel phenomenon observed not only in pure SAR11 cultures but also in samples collected off Helgoland. Furthermore, analysis of samples from the Atlantic, Southern Ocean, and Pacific Ocean revealed the presence of zombie cells, indicating this phenomenon occurs worldwide.

“In our study, zombie cells make up to 10% of all cells in the sea. The global occurrence of zombie cells broadens our understanding of the viral infection cycle”, Brüwer emphasizes. “We suspect that in zombie cells, the nucleic acids contained in the ribosomes are being broken down and recycled to make new phage DNA.”

Brüwer and his colleagues hypothesize that not only SAR11 bacteria, but also other bacteria, can be turned into zombies. Thus, they want to further investigate the distribution of zombie cells and their role in the viral infection cycle.

“This new finding proves that the SAR11 population, despite dividing so fast, is massively controlled and regulated by phages”, stresses Brüwer. “SAR11 is very important for global biogeochemical cycles, including the carbon cycle, therefore their role in the ocean must be redefined. Our work highlights the role of phages in the marine ecosystem and the importance of microbial interactions in the ocean”.

Infected cells and zombie cells

Under the microscope, scientists identified SAR11 zombie cells by their distinct lack of ribosomes. In an example comparing a live, infected SAR11 cell to an infected zombie cell: blue indicates bacterial DNA, yellow shows ribosomes, and purple highlights phage genes. The live cell (upper pictures) displays all three colors, while the zombie cell (lower pictures) lacks the yellow ribosome signal. The final column of images on the right merges these colors, clearly distinguishing the two cell types.

CREDIT

Jan Brüwer/Max Planck Institute for Marine Microbiology

JOURNAL

Nature Communications

DOI

10.1038/s41467-024-48172-w

ARTICLE TITLE

Globally occurring pelagiphage infections create ribosome-deprived cells

LA REVUE GAUCHE - Left Comment: Search results for BACTERIOPHAGE

Human activity over natural inputs determines the bacterial community in an ice core from the Muztag ata glacier

SCIENCE CHINA PRESS

The location of Muztag ata glacier and the ice core sampling strategy. — IMAGE:
THE LOCATION OF MUZTAG ATA GLACIER ON THE TIBETAN PLATEAU AND THE INFLUENCE OF WESTERLY JET AND INDIAN MONSOON ARE SHOWN IN PANEL A. THE ICE CORE SAMPLING STRATEGY IS ILLUSTRATED IN PANEL (B). BRIEFLY, THE 74 M ICE CORE WAS CUT INTO 10 TO 15 CM SECTIONS AND DATED, THEN SECTIONS WITH ENVIRONMENTAL PROXIES AVAILABLE ARE USED FOR DNA EXTRACTION AND BACTERIAL 16S RRNA GENE AMPLICON SEQUENCING.
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CREDIT: ©SCIENCE CHINA PRESS

This study is led by Dr. Yongqin Liu (Institute of Tibetan Plateau Research, Chinese Academy of Sciences). The Tibetan Plateau (TP) has the third-largest number of glaciers after the Antarctic and Greenland. Bacteria, deposited on glacier surfaces through dry and wet deposition, undergo in-situ growth and are subsequently preserved in ice cores following environmental selection pressures such as UV radiation and low temperatures. Since glacier bacteria are largely transported from distant or local sources by atmospheric circulation, changes in source ecosystems can also affect the composition of surface glacier bacteria. Therefore, the characteristics of bacterial communities in ice cores can serve as indicators of past climates and human activities.

The team investigated the bacterial community from a 74 m ice core of Muztag ata glacier on the Tibetan Plateau to link biological indicators with past climate and anthropogenic activities. They observed an increase in bacterial richness throughout the ice core, which was associated with higher NH+4, an indicator of agricultural development. Meanwhile, the evenness demonstrated negative correlations with DOC and MAP, and positive correlation with δ18O, Na+, K+, Mg2+, Ca2+, Cl−, SO42-, and NO3-. These indicators collectively offer promising insights for inferring past climate and environmental changes.

The researchers further investigate the composition of bacterial communities in ice cores. Cluster analysis at the bacterial family level indicates three distinct groupings of samples. Through cluster analysis at the bacterial family level, they uncovered three distinct groupings of samples. Cluster A encompasses the years 1953 to 1991, Cluster B consists of 11 samples from 1933 to 1951, while the majority of samples in Cluster C are dated between 1907 and 1930. It was found that the bacterial community composition was shaped by a combination of human activity, natural inputs, and air temperature, with a pronounced human influence becoming evident after the 1950s. Furthermore, the relative abundance of animal gut-associated bacteria, including Aerococcaceae, Nocardiaceae, Muribaculaceae, and Lachnospiraceae, was associated with livestock number changes in the Central Asian region. Together with other bacterial lineages, they jointly explained 59.8% of the livestock number changes.

"These new findings not only quantify the relationship between bacterial diversity and community composition with past climates and human activities but also highlight how changes in land use, driven by agriculture and livestock, intensify the presence of potentially harmful bacteria on glaciers. This enhances our understanding of regional climate and human activities." Dr. Liu says.

This study provides a comprehensive analysis of the century-long dynamics of bacterial communities in the Muztag Ata ice core. The identified bacterial markers offer valuable insights into past environmental conditions and human activities in the source regions, underscoring the microbial potential in ice core climate studies.

Liu Y, Jiao N, Ji M, Liu K, Xu B, Guo B, Yao T. 2024. Human activity over natural inputs determines the bacterial community in an ice core from the Muztag ata glacier. Science China Earth Sciences, 67(5): 1489–1499, https://doi.org/10.1007/s11430-022-1282-x

The linear regression between bacterial richness (a) and evenness (b) with the dated ice core age is shown. (c) shows the correlation between bacterial richness and evenness with the measured environmental proxies. Significant correlations (at P<0.05) are marked with asterisks. rBC, refractory black carbon; MAP, mean annual precipitation; DOC, dissolved organic carbon.

The community structure variations are visualized based on the Bray- Curtis dissimilarity of bacterial community at the family-level, following Hellinger transformation. Panel (a) shows the hierarchical clustering using complete linkage approach, panel (b) shows the principal component ordination plot with the quadrants labelled, panel (c) shows the distance-based linear modelling
results and the axes are labelled based on human influence (inferred from NH4+ and rBC patterns) and temperature (inferred from δ18O pattern).

Panel (a) shows the annual changes in the relative abundance of animal husbandry indicative lineages (Aerococcaceae, Nocardiaceae, Muribaculaceae, and Lachnospiraceae) and animal stock numbers (cattle and sheep) across the ice core. Panel (b) shows the Pearson correlation between the relative abundance of indicative lineages and animal stock numbers. For panel (a), grey areas represent the consistent year-to-year changing patterns (increase or decrease). The average value before and after 1950 was labelled with dashed lines. Animal stock numbers were obtained from the Russian Agricultural Statistics at https://www.ier.hit-u.ac.jp/rrc/English/pdf/RRC_WP_No67.pdf.

CREDIT

©Science China Press

JOURNAL

Science China Earth Sciences

DOI

10.1007/s11430-022-1282-x

From leaf elements to biomass across forest biomes in the Himalayas

SCIENCE CHINA PRESS

Biomass as a function of the elevation and multi-element traits based functional diversity. — IMAGE:
EXPERIMENTAL DESIGN, INCLUDING (A) THE LOCATION OF THE KANGCHENJUNGA LANDSCAPE IN THE EASTERN HIMALAYAS, NEPAL, (B) THE SITUATION OF FOREST PLOTS ALONG THE WHOLE ELEVATIONAL GRADIENT, AND (C) HYPOTHETICAL FRAMEWORK OF ELEMENT-BASED TRAIT DIVERSITY AND (D) DECLINING BIOMASS ALONG THE STUDY GRADIENT. THE FRAMEWORK SHOWS MASS-RATIO (FOCUSING ON COMMUNITY WEIGHTED MEAN, CWM, WHERE TRAIT VALUE OF DIFFERENT SPECIES WAS SYMBOLIZED AS ARROWS POINTING UPWARD) AND COMPLEMENTARITY EFFECTS (FOCUSING ON FUNCTIONAL DIVERGENCE, FD, WHERE E1 TO E5 INDICATE 5 ELEMENTS IN TREE LEAVES AND REPRESENT NICHE PARTITIONING IN THE TRAIT SPACE. THE ELEVATION GRADIENT IS CHARACTERIZED BY: LOW (ELEVATION < 1000 M), MID (ELEVATION 1000-3000 M), AND HIGH-ELEVATION SITES (ELEVATION > 3000 M).
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CREDIT: ©SCIENCE CHINA PRESS

The growth, development, and functioning of plants in various environments depend on multiple elements. However, our understanding of how the element concentrations in leaves that are associated with plant functioning and adaptation affect biomass in tree communities along elevation has been limited. A study led by Prof. Eryuan Liang (Institute of Tibetan Plateau Research, Chinese Academy of Sciences), and Dr. Nita Dyola (Institute of Tibetan Plateau Research, Chinese Academy of Sciences and Université du Québec à Chicoutimi), together with the co-authors, demonstrated the linkages of ten leaf element (carbon, nitrogen, phosphorus, potassium, calcium, magnesium, zinc, iron, copper and manganese) contents in 1,859 trees from 116 species in shaping biomass accumulation from tropical forests (80 m asl) to alpine treeline (4200 m asl) in the Kangchenjunga Landscape, located in the eastern Nepal Himalayas, which is one of the most diverse regions in the world.

The study, published in the Science China Earth Sciences, explored the mechanisms regulating forest biomass by assessing the relative change in the mass-ratio effect (i.e., indicating dominant trait affecting biomass) and complementarity effect (i.e., indicating partitioning of resources) based on multiple leaf elements. The study highlighted that elevation plays a crucial role in regulating trait diversity among plant species and their biomass accumulation in the Himalayas (see the figure below).

The study revealed that a combination of elements and elevation better explained the variation in biomass, accounting for 52.2% of the variance, compared to the individual elemental diversity, which accounted for 0.05% to 21% of the variance in biomass. The findings highlighted the significance of resource partitioning at low elevations and competition in the middle elevations, both of which were positively associated with forest biomass. Although high variation in leaf nutrients improves species’ adaptability to changing environments, it also poses challenges by reducing biomass accumulation in stressful sites at higher elevations.

This study provides a roadmap to comprehend and predict the effect of elevation-dependent environmental shifts, on the functional diversity of elemental traits that shape biomass accumulation across biomes. This knowledge presents a new approach to explore the range of chemical traits that modulate biomass and ecosystem functioning, which is crucial for conserving and managing biodiversity in mountain ecosystems.

See the article:

Dyola N, Liang E, Peñuelas J, Camarero JJ, Sigdel SR, Aryal S, Lin W, Liu X, Liu Y, Xu X, Rossi S. 2024. Linking leaf elemental traits to biomass across forest biomes in the Himalayas. Science China Earth Sciences, 67(5): 1518-1528. https://doi.org/10.1007/s11430-023-1271-4

JOURNAL

Science China Earth Sciences

Harnessing plant viruses for the delivery of genome editing reagents in diverse plant species

BEIJING ZHONGKE JOURNAL PUBLISING CO. LTD.

Exploiting viral vectors to deliver genome editing reagents in plants — IMAGE:
DELIVERING GENOME EDITING REAGENTS IN PLANTS USING POSITIVE-STRAND RNA VIRUSES (A) OR NEGATIVE-STRAND RNA VIRUSES (B) FOR HERITABLE EDITS.
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CREDIT: BEIJING ZHONGKE JOURNAL PUBLISING CO. LTD.

Genome editing holds great promise for the molecular breeding of plants, yet its application is hindered by the shortage of simple and effective means of delivering genome editing reagents into plants. Conventional plant transformation-based methods for the delivery of genome editing reagents into plants often involve prolonged tissue culture, a labor-intensive and technically challenging process for many elite crop cultivars. This bottleneck prevents the genomes from many elite crop cultivars from being edited in a cost-effective manner. Besides, genome editing strategies based on homology-directed repair (HDR) are highly versatile, but often depend on a large amount of donor DNA delivered, which can be difficult to achieve with many conventional methods. Both RNA viruses and DNA viruses have been employed to overcome these technical challenges.

RNA viruses have been harnessed for the delivery of the core components involved in genome editing in plants. The limitation in the capacity of positive-strand RNA viruses (PSVs) is compensated by their ability to invade germline cells in planta and induce heritable edits. Accordingly, PSV-based delivery strategies have been mostly applied to introduce guide RNA molecules into plant hosts that express the matching Cas nuclease gene, which often exceeds the size limit that PSVs can accommodate. On the contrary, negative-strand RNA viruses (NSVs) can accommodate longer DNA fragments, such as one encoding the entire sequence-specific nuclease machinery, but rarely enters the germline cells. As a result, NSVs-based delivery strategies often entail a subsequent plant regeneration process if heritable edits are desired.

Precision edits achieved via HDR usually involves an artificially supplied donor DNA as the repair template, which needs to be delivered at a high copy number to be effective. Geminiviruses comprise a family of plant DNA viruses whose genomes can replicate to a very high copy number in plant cells. This feature makes them ideal vectors for the delivery of repair donors. Geminiviral replicons have been successful utilized to generate specific editing outcomes in wheat, tomatoes, and tobacco etc.

A general trade-off between cargo capacity and vector mobility exists for currently available viral vectors. PSVs are promising tools for tissue culture-free gene editing, but they rely on an existing Cas-expressing line due to the limited capacity of the viral vector. NSV-based vectors can accommodate the entire CRISPR/Cas machinery, and thus can be used for genome editing in a transgene-free context, but often rely on a subsequence tissue culture process to recover plants carrying heritable edits. Similarly, GVRs are modified into replicon vectors with no infectivity and minimal mobility to make room for extra nucleotide sequences. It is desirable to develop viral vector systems with not only the ability to perform cargo delivery into germline cells, in planta, but also sufficient capacity for the complete CRISPR/Cas components. Meanwhile, more compact sequence-specific nucleases are strong candidates to be delivered using virus-based systems. Besides, it is worth exploring new components to be fused with the delivered cargos to enhance the systemic movement of the genome editing reagents to achieve germline edits. Furthermore, broad-spectrum viral delivery systems are required for application in a broader range of crop species. Biosafety and risk assessment of the application viral vectors are also worth additional investigation to reduce unintended burden on humans and the ecosystem.

In summary, the use of viral vectors to deliver genome editing components offers potential solutions to many current technical bottlenecks involved in genome editing in plants. More efficient delivery methods capable of generating heritable edits in a simple manner may be established in the future through the exploitation of novel viral species and engineered existing viruses for improved performance.

See the article:

Exploiting viral vectors to deliver genome editing reagents in plants

https://link.springer.com/article/10.1007/s42994-024-00147-7

JOURNAL

aBIOTECH

DOI

10.1007/s42994-024-00147-7

ARTICLE TITLE

Exploiting viral vectors to deliver genome editing reagents in plants

DOI

10.1007/s11430-023-1271-4

Furry thieves are running loose in a Maine forest, UMaine research shows

UNIVERSITY OF MAINE

Small-mammal-study-news-feature — IMAGE:
A MOUSE SITS ON A MOSSY LOG IN A MAINE FOREST.
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CREDIT: PHOTO COURTESY OF BRIGIT HUMPHREYS

Scattered across the Penobscot Experimental Forest are veritable treasure troves for its denizens, each containing riches beyond comprehension. These caches do not contain gold or jewels — they’re filled with eastern white pine seeds and were placed by a team of researchers at the University of Maine for one purpose: to catch furry thieves red-handed.

Brigit Humphreys, a UMaine graduate student studying ecology and environmental science, has been working in the forest, which sits about 10 miles north of Bangor, for the past two years in an effort to determine which animal personalities are predisposed to pilfering.

As part of a National Science Foundation-funded research project, Humphreys has been studying the behavior of small mammals in the wild. Her research adds to a growing body of knowledge showing that the unique personalities of individual small mammals play a critical role in forest regeneration by impacting seed dispersal. It also complements a larger project that has been eight years in the making and is nearing completion.

“The point of the project was to figure out how small mammal personality and animal personality in general influence different ecological processes,” Humphreys said. “We’re focused on small mammals because they’re a great study system. They’re abundant, we get a really good sample size and we can actually conduct experiments on them in the forest. Seed dispersal is a super important aspect to Maine’s economy, recreation and aesthetics. A lot of research focuses at the species or community level, but many of the individual aspects have been ignored in science. The idea is to bring more attention to the individual and how variation and personality at the individual level is actually really important for ecosystems, tree growth and forest regeneration.”

Humphreys has worked under the direction of professor Alessio Mortelliti of the Department of Wildlife, Fisheries, and Conservation Biology. From June-October 2022, Humphreys and a team of researchers set traps for small mammals, including squirrels, chipmunks, mice, voles and shrews. They worked in a six-grid system, slowly moving about 150 traps from one grid to another. Upon catching the animals, the team collected data about their personality traits and tagged each of them.

Once a grid was cleared of traps, Humphreys and her team planted artificial seed caches across the area, equipping each with a circular antenna buried around the cache. The caches contained eastern white pine seeds, which are an economically important species in Maine and a consistently preferred seed species among the small mammals involved in the study. Game cameras were also set up to observe pilferers in the act.

“The idea is when an individual that we have tagged crosses over the antenna, the antenna picks up on their unique tag, so we know what the personality of that individual was,” Humphreys said.

Her findings indicate that small mammal personality determines the effectiveness of pilferage in mice and voles, with some individuals being more successful at stealing seeds than others. The most accomplished thieves: deer mice.

“We found that more exploratory deer mice were more likely to find caches to pilfer, which makes a lot of sense because they’re likely moving around more and they don’t consider predation risk as much, so they’re able to find these caches and steal them. Those were our main personality results,” Humphreys said. “We found that individuals with a lower body condition, so skinnier animals, were more likely to pilfer because they were desperately hungry. We also found a sex effect. Female voles were more likely to pilfer, which aligns with past research on the same species of voles.”

Humphreys and her team observed many other curious and hungry species over the course of the study as well.

“We had over 10 different species come and pilfer the caches,” Humphreys said. “Some of them were unexpected, like raccoons came and took some of the seeds, which was interesting. The other common pilferers were American red squirrels, eastern chipmunks, Sorex shrews and jumping mice. For the jumping mice there were only a few individuals that we caught, but the ones that were present in our areas were very effective. They got like 10 caches in a night.”

Humphreys’ findings were recently published in the Journal of Animal Ecology as part of the special feature: “Intraspecific Variation in Ecology and Evolution.” She’s currently working on the last piece of the overall project, which focuses on comparing behavioral diversity in areas with varying styles of forest management.

“The take-home message of all the research we are doing is that individuals are important,” Humphreys said. “There’s a big push in the science community to conserve biodiversity, but beyond biodiversity, we have to be conserving behavioral diversity within a species if we truly want to have fully functional ecosystems.”

JOURNAL

Journal of Animal Ecology

DOI

10.1111/1365-2656.14059

ARTICLE TITLE

Pilfering personalities: Effects of small mammal personality on cache pilferage

ARTICLE PUBLICATION DATE

18-Mar-2024

Pickleball courts in a legal pickle #ASA186

When advising on the noise associated with pickleball, loudness is just one of many concerns, and solutions require infrastructure or limitations on play.

Reports and Proceedings

ACOUSTICAL SOCIETY OF AMERICA

OTTAWA, Ontario, May 17, 2024 – Pickleball Legal Consultant is a job title that likely did not exist a decade ago, but as pickleball courts infiltrate neighborhoods to satiate an appetite for a sport whose namesake is a snack, communities take issue with the resulting influx of noise. Now homeowners’ associations and city councils face litigation by those whose lives are disrupted by pickleball’s din.

Charles Leahy, an attorney, retired mechanical engineer, and former HOA board member became interested in this issue after his HOA dismissed the recommendations of noise consultants and failed to install noise absorbing barriers. Litigation over noise nuisance ensued and threatens closure of the courts.

Leahy sought to understand how acoustic engineers assess the noise, how they fashion their recommendations, and what best practices engineers can employ to persuade the community that the noise is real and needs to be mitigated. He will present his work Friday, May 17, at 8:35 a.m. EDT in a session dedicated to pickleball as part of a joint meeting of the Acoustical Society of America and the Canadian Acoustical Association, running May 13-17 at the Shaw Centre located in downtown Ottawa, Ontario, Canada.

“Compared to tennis, pickleball is a much smaller court, easier to learn, and especially accessible to seniors,” said Leahy. “Each tennis court can become up to four pickleball courts. Tennis involves a soft and compressible ball and a racket with strings. Pickleball is a hard plastic ball and a hard paddle. Tennis produces a ‘thunk’ sound versus pickleball ’pop,’ which is louder, sharper, more piercing, and more frequent. Thus, more annoying.”

Communities looking to invest in – and those facing lawsuits because of – the courts often seek out engineering consultants to advise them. Leahy examined over 70 pickleball consultant noise reports and compared their recommendations with the American National Standard Institute. He found many reports considered only the decibels associated with the noise, but other factors are important too.

“It’s not just the loudness, it’s the impulsive sharpness and randomness of the ‘pops,’” said Leahy. “It’s the persistence and repetition of the random noises over many hours a day, usually seven days a week.”

His best recommendation is to build courts far from homes, at least 600-800 feet away to allow the sound to naturally dissipate. Less desirable (or more difficult or costly) solutions include enclosing the courts within a building or wall barriers or using less noisy paddles and balls.

“Pickleball has a highly impulsive noise, with each court generating about 900 pop noises per hour,” said Leahy. “It’s incompatible with residential living. Cities can also locate pickleball in industrial and commercial neighborhoods rather than close to homes.

“The benefits of pickleball to the players are undeniable, and the demand for more pickleball courts is real and genuine. However, there needs to be more research, more planning and prevention, and more effort to avoid ending up in front of the judge and jury.”

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----------------------- MORE MEETING INFORMATION -----------------------

Main meeting website: https://acousticalsociety.org/ottawa/
Technical program: https://eppro02.ativ.me/src/EventPilot/php/express/web/planner.php?id=ASASPRING24

ASA PRESS ROOM

In the coming weeks, ASA's Press Room will be updated with newsworthy stories and the press conference schedule at https://acoustics.org/asa-press-room/.

LAY LANGUAGE PAPERS

ASA will also share dozens of lay language papers about topics covered at the conference. Lay language papers are summaries (300-500 words) of presentations written by scientists for a general audience. They will be accompanied by photos, audio, and video. Learn more at https://acoustics.org/lay-language-papers/.

PRESS REGISTRATION

ASA will grant free registration to credentialed and professional freelance journalists. If you are a reporter and would like to attend the hybrid / in-person meeting or virtual press conferences, contact AIP Media Services at media@aip.org. For urgent requests, AIP staff can also help with setting up interviews and obtaining images, sound clips, or background information.

ABOUT THE ACOUSTICAL SOCIETY OF AMERICA

The Acoustical Society of America is the premier international scientific society in acoustics devoted to the science and technology of sound. Its 7,000 members worldwide represent a broad spectrum of the study of acoustics. ASA publications include The Journal of the Acoustical Society of America (the world's leading journal on acoustics), JASA Express Letters, Proceedings of Meetings on Acoustics, Acoustics Today magazine, books, and standards on acoustics. The society also holds two major scientific meetings each year. See https://acousticalsociety.org/.

ABOUT THE CANADIAN ACOUSTICAL ASSOCIATION/ASSOCIATION CANADIENNE D’ACOUSTIQUE

•            fosters communication among people working in all areas of acoustics in Canada
•            promotes the growth and practical application of knowledge in acoustics
•            encourages education, research, protection of the environment, and employment in acoustics
•            is an umbrella organization through which general issues in education, employment and research can be addressed at a national and multidisciplinary level

The CAA is a member society of the International Institute of Noise Control Engineering (I-INCE) and the International Commission for Acoustics (ICA) and is an affiliate society of the International Institute of Acoustics and Vibration (IIAV). Visit https://caa-aca.ca/.

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From fungi to fashion: mushroom eco-leather is moving towards the mainstream

Mycelium leather – a bio-fabricated material made from the roots of fungi – has growing potential to scale up

CAMBRIDGE UNIVERSITY PRESS

As fashion designers look for alternatives to leather, growing mycelium – or fungi-based – ‘leather’ substitutes using a new paste media has opened up the possibility of growing this bio-fabricated material faster, and of cultivating it more easily.

Researchers investigating how to grow and cultivate mycelium leather more effectively tested their hypotheses by growing and harvesting mycelium leather mats using a new paste of their own design as a substrate. Their findings are published in the Cambridge University Press journal Research Directions: Biotechnology Design.

Mycelium materials offer a low-cost and environmentally sustainable alternative to some petroleum-based materials and a more sustainable and ethical alternative to animal-derived leather. They can be grown on a wide variety of agricultural and industrial organic waste or side streams.

With greater uptake and scaling of production, these products have the potential to become more economically viable than established traditional materials. They can also be optimised to meet consumer demands.

The researchers examined mushroom compatibility for the purposes of leather mat development by using two fungal species: Ganoderma lucidum (reishi), a medicinal mushroom widely used within bio-design; and Pleurotus djamor (pink oyster), a gourmet mushroom that has the tendency to quickly colonise the substrate and enter the fruiting stage – meaning it produces mushroom fruit bodies fast.

By carefully formulating a new paste substrate for the mushrooms to grow in, the researchers sought to enhance nutrient availability from the mushrooms; enable their scalability; and streamline their cultivation processes.

Different species of mushrooms have their own preferences for substrates, meaning that an important part of growing mushrooms – and mycelium leather – involves matching one’s mushrooms with the best available substrate. Common substrates include straw, coffee grounds, and manure.

Mycelium leather is produced by growing the fungus as a biological tissue or mat on top of a liquid or solid substrate, or as fungal biomass in submerged liquid fermentation. Solid-state fermentation offers superior growth conditions; however, liquid-state surface fermentation allows mycelium mats to be harvested more easily, although growth rates are slower due to lower oxygen levels. Lastly, liquid-state fermentation gives improved yields, yet the product must be further manipulated to produce a mycelium mat.

As a response to these challenges, the researchers developed a new method for cultivation based on a paste consistency substrate that offers the benefits of high nutrient content as well as small nutrient particle size, aiding the uptake of nutrients.

The researchers found that by using this particular paste, they were able to grow thicker mycelial mats over a shorter period of time in comparison to growth on nutrient-enriched agar or liquid culture. Moreover, further benefits of this growth method became apparent during the harvesting stage, as the mats had grown strong enough that it was possible to peel them without needing to cut the sheet.

Lead author of the study Assia Crawford, of the University of Colorado in the United States, said:

“As our world searches for sustainable alternatives to traditional materials, there has been growing interest in using living organisms to produce biodegradable material substitutes with low environmental impact – such as mycelium leather, which is an eco-friendly leather alternative.

“The extensive treatment needed to transform hide into traditional leather comes with high environmental costs, Moreover, petrochemical alternatives like faux leather, which have become increasingly popular in response to the challenges of animal leather production and associated ethical concerns, also have significant environmental impacts associated with the extraction of fossil fuels, long degradation spans, and potential off-gassing risks. Developing better alternatives is crucial in today’s environmentally fragile world.

“Bio-design methods like the ones explored in our study contribute to developing high-quality, scalable, biodegradable material alternatives. These in turn have the potential to address the environmental challenges of high textile consumption. Indeed, the flexible nature of pure mycelial mats is a compelling potential substitute for non-woven materials such as animal-derived leather and petroleum-based faux leather alternatives. As researchers, we have a responsibility to continue developing better materials in response to the climate crisis, which is what the study aims to do.”

JOURNAL

Research Directions Biotechnology Design

DOI

10.1017/btd.2024.6

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

From fungi to fashion: mushroom eco-leather is moving towards the mainstream