Traditional plant-based products provide nutritional benefits and support cultural heritage; however, their sale in urban informal markets raises potential food safety considerations. We characterized the microbiota of five traditional dried plant products (baobab, masau, nyii, dinawa, and lude) obtained from three informal markets in South Africa (n = 51 samples) using 16S rRNA gene sequencing and quantitative real-time PCR; bacterial isolates (n = 87) were further evaluated using selected phenotypic assays. Bacterial abundance and composition varied across products and vendors. Baobab exhibited the highest microbial richness (1460 ASVs) but relatively low bacterial loads (106 16S rRNA gene copies g-1), whereas dried leafy greens showed the lowest richness (470 ASVs) but the highest bacterial abundance (109 copies g-1). Across products, higher bacterial diversity correlated with genera such as Bifidobacterium and Prevotella, while higher bacterial abundance correlated with genera such as Salmonella, Vibrio, and Acinetobacter. Notably, health implications of detected taxa cannot be inferred from genus-level identification based on 16S rRNA gene sequencing. Phenotypic traits observed among selected isolates included growth in the presence of several antibiotics (particularly sulfadiazine and ampicillin), protease activity, and inhibition of indicator strains under laboratory conditions. Overall, traditional dried plant foods harbor diverse microbial communities shaped by plant characteristics and vendor-related practices, highlighting the importance of improved handling and drying practices.

In a large field trial on sandy loam, Lama et al. (2022)1- albeit involuntary - tested the effect of drought on the performance of 300 genotypes during two contrasting years: 2017 (cool and wet) and 2018 (hot and dry). Remarkably, some genotypes achieved yields under drought conditions (2018) comparable to established high-yielding varieties. The reason for this remains unclear.One possible explanation is that this positive effect is linked to modifications of rhizosphere wettability. Sandy soils are known to be susceptible to water repellency upon drying, and several crops, such as maize, barley, and wheat, can modify soil wettability through root exudation2. However, it is still uncertain whether rhizosphere water repellency in sandy soils is an advantage, as it can delay rewetting and thereby reduce biological activity and potentially limit root water uptake.In this study, we investigated the effect of rhizosphere-induced wettability modifications on water dynamics in naturally water-repellent sandy soil. Using time-series neutron radiography, we quantified rewetting dynamics following a dry-down experiment. While the bulk soil exhibited reduced rewetting, preferential rewetting was observed in the rhizosphere of maize. This finding may help to explain why certain plants benefit from reduced precipitation in sandy soils. Firstly, rewetting occurs preferentially in the rhizosphere, where it can directly support microbial activity and root water uptake. Secondly, localized rewetting may reduce nutrient leaching and promote nutrient retention and turnover through localized enzyme activity. References1. Lama, S., Vallenback, P., Hall, S. A., Kuzmenkova, M. & Kuktaite, R. Prolonged heat and drought versus cool climate on the Swedish spring wheat breeding lines: Impact on the gluten protein quality and grain microstructure. Food Energy Secur. 11, e376 (2022).2. Naveed, M. et al. Surface tension, rheology and hydrophobicity of rhizodeposits and seed mucilage influence soil water retention and hysteresis. Plant Soil 437, 65–81 (2019).

The decline in plant biodiversity is evident at global scale, but little is known about the loss of microbial diversity associated with diverse plant phyla and their influencing factors. This study investigates the microbial diversity associated with mosses and co-occurring vascular plants in the Alpine ecosystem, focusing on 52 plant "twins" growing on contrasting soil types (carbonate and silicate). Despite co-occurring in the same soil, mosses harbored significantly higher microbial richness and diversity than vascular plants. Across all samples, mosses supporting a total of 3,435 bacterial ASVs and 1,174 fungal ASVs. In contrast, vascular plants hosted a total of 1,760 bacterial ASVs and 911 fungal ASVs. Plant phyla strongly influenced microbial community composition, with vascular plants exhibiting a selective microbial assembly strategy, while mosses showed greater environmental influence. Soil type significantly influenced microbial composition in both plant types, with carbonate soils supporting greater bacterial richness, particularly in mosses. Linear discriminant analysis effect size (LEfSe) analysis highlighted consistent enrichments of Proteobacteria, i.e., Sphingomonadales, Rhizobiales, Burkholderiales and, Pseudomonadales, in vascular plants across soil types, whereas mosses displayed distinct microbial enrichment patterns between carbonate and silicate soils, suggesting a higher environmental connectedness. Our findings demonstrated that plant phyla are a major determinant of the phyllosphere microbiota, and that mosses represent a currently untapped source of microbial biodiversity. This study highlights the importance of considering both host traits and environmental factors for protecting microbial biodiversity and implementing them in global strategies for restoring biodiversity.

Aureobasidium pullulans is a globally distributed fungus commonly found in plant-associated and anthropogenic environments. Known for its antagonistic activity against plant pathogens, it is widely used as a biocontrol agent in sustainable agriculture. Despite its prevalence in edible plant tissues and frequent environmental exposure, its broader role within microbiomes and potential relevance for human health remain underexplored. In this perspective article, we highlight the global distribution of A. pullulans based on publicly available sequencing data and examine its ecological function from a microbiome-based viewpoint. Our synthesis supports the view of A. pullulans as a safe, plant-beneficial symbiont with high value for sustainable crop protection and potential relevance for the One Health framework. Future microbiome research should further explore its functional roles within plant and human-associated microbiomes to better harness its benefits while ensuring biosafety across ecosystems.

ABSTRACT Microorganisms are fundamental to life on Earth, influencing biogeochemical processes, soil fertility, and the health of humans, animals and plants. Human activities have left a remarkable footprint on the environment, including global microbiomes. Enhancing awareness and improving education about microbiome functions can contribute to a sustainable economy and resilient systems. However, public understanding of microbiome science is hindered by misinformation and limited accessible educational resources. To address this, we developed the massive open online course (MOOC) ‘Microbiome & Health’, available on iMooX.at and YouTube. The course, structured into six units, covers microbiome concepts, methodologies, human and plant microbiomes, antibiotic resistance, and environmental impacts, aligning with the One Health concept and the Sustainable Development Goals of the United Nations. Initial results show that the MOOC provides the means to increase microbiology literacy, with 73.2% external participation and above‐average completion rates. Integration as a mandatory component in university courses has improved student performance, halting declining grades and pass rates. This highlights the MOOC's potential to enhance public and academic understanding of microbiome science, fostering informed decisions for sustainable health and environmental stewardship as well as paving the way for new microbiome‐based solutions in biotechnology.

Komagataella phaffii has become a key player in biotechnology used for the production of heterologous proteins with numerous GRAS notices and QPS status released in the past years. While most of these descriptions and scientific studies focus on strain engineering, products and cultivation processes, this paper provides fundamental data about the general viability of K. phaffii after post-production biomass treatments and co-incubations with non-sterile soil and water samples. A comparison of different K. phaffii strains uncovered a high thermal sensitivity for all tested strains, which was further enhanced under alkaline conditions. A rapid reduction in the viable cell number started at approx. 52 °C and terminated in a full loss of 109 viable cells per milliliter within seconds at 70 °C. Survival rates of untreated non-GMO and GMO K. phaffii strains in water- and soil-slurry-microcosms demonstrated that the number of viable K. phaffii cells decreased rapidly and comparably to a Saccharomyces cerevisiae reference. No mating events were detected under these environmental conditions. These findings supported assumptions that K. phaffii is highly specialized and not a ubiquitous microorganism as described for other yeasts. Finally, intrigued by the low survival outside optimal laboratory conditions, K. phaffii biomass was evaluated in mesophilic anaerobic digestion processes for energy production. Enhanced methane yields and a concomitant loss of viable K. phaffii cells were demonstrated.

Abstract In the last two decades, new discoveries from microbiome research have changed our understanding of human health. It became evident that daily habits and lifestyle choices shape the human microbiome and ultimately determine health or disease. Therefore, we developed ‘Tiny Biome Tales’ (https://microbiome.gamelabgraz.at/), a science pedagogy video game designed like a scientific review based exclusively on peer‐reviewed articles, to teach about the influence of lifestyle choices on the human microbiome during pregnancy, early and adult life, and related health consequences. Despite the scientific character, it can be played by a broad audience. Here, we also present a scientific assessment and showed that playing the game significantly contributed to knowledge gain. The innovative style of the ‘gamified review’ represents an ideal platform to disseminate future findings from microbiome research by updating existing and adding new scenes to the game.

Microorganisms colonizing plant roots co-exist in complex, spatially structured multispecies biofilm communities. However, little is known about microbial interactions and the underlying spatial organization within biofilm communities established on plant roots. Here, a well-established four-species biofilm model (Stenotrophomonas rhizophila, Paenibacillus amylolyticus, Microbacterium oxydans, and Xanthomonas retroflexus, termed as SPMX) was applied to Arabidopsis roots to study the impact of multispecies biofilm on plant growth and the community spatial dynamics on the roots. SPMX co-culture notably promoted root development and plant biomass. Co-cultured SPMX increased root colonization and formed multispecies biofilms, structurally different from those formed by monocultures. By combining 16S rRNA gene amplicon sequencing and fluorescence in situ hybridization with confocal laser scanning microscopy, we found that the composition and spatial organization of the four-species biofilm significantly changed over time. Monoculture P. amylolyticus colonized plant roots poorly, but its population and root colonization were highly enhanced when residing in the four-species biofilm. Exclusion of P. amylolyticus from the community reduced overall biofilm production and root colonization of the three species, resulting in the loss of the plant growth-promoting effects. Combined with spatial analysis, this led to identification of P. amylolyticus as a keystone species. Our findings highlight that weak root colonizers may benefit from mutualistic interactions in complex communities and hereby become important keystone species impacting community spatial organization and function. This work expands the knowledge on spatial organization uncovering interspecific interactions in multispecies biofilm communities on plant roots, beneficial for harnessing microbial mutualism promoting plant growth.

In recent years, there has been a significant shift towards industrialization in food production, resulting in the implementation of higher hygiene standards globally. Our study focused on examining the impact of hygiene standards on tempeh, a popular Rhizopus-based fermented soybean product native to Indonesia, and now famous around the world. We observed that tempeh produced with standardized hygiene measures exhibited a microbiome with comparable bacterial abundances but a markedly different community structure and function than traditionally produced tempeh. In detail, we found a decreased bacterial abundance of lactobacilli and enterobacteria, bacterial diversity, different indicator taxa, and significantly changed community structure in industrial tempeh. A similar picture was found for functional analysis: the quantity of bacterial genes was similar but qualitative changes were found for genes associated with human health. The resistome of tempeh varied based on its microbiome composition. The higher number of antimicrobial resistance genes in tempeh produced without standardized hygiene measures mainly belong to multidrug efflux pumps known to occur in plant-based food. Our findings were confirmed by functional insights into genomes and metagenome-assembled genomes from the dominant bacteria, e.g. Leuconostoc, Limosilactobacillus, Lactobacillus, Enterococcus, Paenibacillus, Azotobacter and Enterobacter. They harboured an impressive spectrum of genes important for human health, e.g. for production of vitamin B1, B7, B12, and K, iron and zinc transport systems and short chain fatty acid production. In conclusion, industrially produced tempeh harbours a less diverse microbiome than the traditional one. Although this ensures production at large scales as well as biosafety, in the long-term it can lead to potential effects for human gut health.

Exposure to air pollution affects health of all organisms on earth but the impact on the plant microbiome is less understood. Here, we link the Air Quality Index with the dust and apple epiphytic and endophytic microbiome across the city of Graz (Austria). The microbiome of the apple episphere, peel endosphere and pulp endosphere, and surrounding dust was analyzed. Our results show that the fungal communities were more influenced by air quality than bacterial communities. Bacterial communities, instead, were more specific for the individual sample types, especially noticeable in the pulp endosphere. The microbiome of each sample type was comprised of distinct microbial communities. Overall, the bacterial communities were highly dominated by Proteobacteria followed by Bacteroidota and Actinobacteriota, and the fungal communities were dominated by Ascomycota followed by Basidiomycota. With lower air quality, the relative abundance of the fungal orders Hypocreales and Pleosporales decreased in the apple episphere and the peel endosphere, respectively. Interestingly, an unexpectedly high level of similarity was observed between the bacterial communities of dust and peel endosphere, while the epiphytic bacterial community was significantly different compared to the other samples. We suggested that dust served as a potential microbial colonization route for the fruit microbiome as most bacteria (55%) colonizing the peel endosphere originated from dust. In conclusion, air quality affects the microbiome of edible plants, which can cause health consequences in humans. Therefore, this knowledge should be considered in urban and horticultural farming strategies.

AbstractDespite that climate change is currently one of the most pervasive challenges, its effects on the plant-associated microbiome is still poorly studied. The aim of this study was to evaluate the impact of the independent and combinatory effect of climate warming and drought on the microbiome assembly of oak from seed to seedling. In a multifactorial experimental set up, acorns were subjected to different temperatures (15 °C, 20 °C, and 25 °C) and soil moisture levels (drought (15%) and control (60%)) from germination until the seedling stage, after which the bacterial and fungal communities associated to the rhizosphere and phyllosphere were characterized by amplicon sequencing and qPCR. The results showed a stronger effect of temperature on fungal than on bacterial diversity and the effect was more pronounced in the phyllosphere. Under drought condition, temperature had a significantly negative effect on phyllosphere fungal diversity. In the rhizosphere, temperature had a significant effect on the fungal community composition which was primarily caused by species turnover. Regardless of temperature, Actinobacteriota was significantly enriched in drought, a group of bacteria known to increase plant drought tolerance. This study provides new insights into the effect of climate change on the plant microbiome in natural ecosystems.

Nitrogen (N) is a crucial nutrient for the growth and activity of rhizosphere microorganisms, particularly during drought conditions. Plant root-secreted mucilage contains N that could potentially nourish rhizosphere microbial communities. However, there remains a significant gap in understanding mucilage N content, its source, and its utilization by microorganisms under drought stress. In this study, we investigated the impact of four maize varieties (DH02 and DH04 from Kenya, and Kentos and Keops from Germany) on the secretion rates of mucilage from aerial roots and explored the origin of mucilage N supporting microbial life in the rhizosphere. We found that DH02 exhibited a 96

Tempeh, a soybean product from Indonesia, is created through fermentation by Rhizopus spp. and associated bacteria. Here, we aim to get an overview of the variability of the tempeh microbiota across Indonesia and disentangle influencing factors. We found high variability in bacterial abundance (103 - 109 copies g-1), richness (nASV = 40 - 175 ASVs), and diversity (H' = 0.9 - 3.5) in tempeh. The primary factor affecting this variation was the region, where the tempeh was produced. Interestingly, tempeh samples obtained from geographically close areas tended to share similar bacterial profiles, suggesting a "terroir" of tempeh. Additionally, tempeh wrapped in banana leaves had a higher abundance of enterobacteria in comparison to tempeh wrapped in plastic but also tended to have a higher total bacterial and lactobacilli abundance. Despite all variability, the tempeh core microbiome consists Lactobacillales and Enterobacteriales. This study demonstrates a high variability of bacterial diversity in traditional tempeh from local producers highlighting a strong regional influence across Indonesia.

The holobiont Holobiont theory is more than 80 years old, while the importance of microbial communities for plant holobionts was already identified by Lorenz Hiltner more than a century ago. Both concepts are strongly supported by results from the new field of microbiome research. Here, we present ecological and genetic features of the plant holobiont that underpin principles of a shared governance between hosts and microbes and summarize the relevance of plant holobionts in the context of global change. Moreover, we uncover knowledge gaps that arise when integrating plant holobionts in the broader perspective of the holobiome as well as one and planetary health concepts. Action is needed to consider interacting holobionts at the holobiome scale, for prediction and control of microbiome function to improve human and environmental health outcomes.

Abstract Introduction The consequences of overfertilization on agricultural and native ecosystems are well‐documented, but the impact of reduced fertilization on plant–microbe interactions is less understood. Here, we analysed the impact of different nitrogen (N) fertilization regimes over two subsequent growing seasons on the seed microbiome of winter oilseed rape (Brassica napus L.). Materials and Methods Seed microbial diversity, composition, and abundance were analysed by a combined approach of amplicon sequencing, quantitative real‐time PCR, and microscopy. A germination assay was conducted to quantify bacteria and nifH genes in roots. Results Two consecutive years of either low or high N fertilization resulted in a significant shift in seed microbiota; nine discriminating bacterial orders and 32 bacterial features were identified. Among them, potentially N‐fixing bacteria (Rhizobiales and Rhizobium) were identified as biomarkers for low N fertilization. Moreover, quantitative measurements revealed that 16S ribosomal RNA (rRNA) and bacterial nifH gene counts were significantly higher under lower N availability. Relative to total 16S rRNA genes, seeds and roots contained 0.002% and 0.3% nifH genes on average, respectively. The alternation of N levels between the first and the second growing season (high to low, or low to high) had, however, no impact on seed microbiota, suggesting that a low N availability for at least two generations is required to enrich N‐fixing taxa in seeds. Conclusion Our study revealed a flexible, environmentally influenced seed microbiome assembly and suggests innovative microbiome management via biological nitrogen fixation to optimize fertilization regimes in future agriculture.

Diversity of the gut microbiota is crucial for human health. However, whether fruit and vegetable associated bacteria contribute to overall gut bacterial diversity is still unknown. We reconstructed metagenome-assembled genomes from 156 fruit and vegetable metagenomes to investigate the prevalence of associated bacteria in 2,426 publicly available gut metagenomes. The microbiomes of fresh fruits and vegetables and the human gut are represented by members in common such as Enterobacterales, Burkholderiales, and Lactobacillales. Exposure to bacteria via fruit and vegetable consumption potentially has a beneficial impact on the functional diversity of gut microbiota particularly due to the presence of putative health-promoting genes for the production of vitamin and short-chain fatty acids. In the human gut, they were consistently present, although at a low abundance, approx. 2.2%. Host age, vegetable consumption frequency, and the diversity of plants consumed were drivers favoring a higher proportion. Overall, these results provide one of the primary links between the human microbiome and the environmental microbiome. This study revealed evidence that fruit and vegetable-derived microbes could be found in the human gut and contribute to gut microbiome diversity.

Plant diversification and co-evolution shaped the plant microbiome and vice versa. This resulted in a specific composition of the plant microbiome and a strong connection with the host in terms of functional interplay. Symbionts are part of the microbiota, and important for the plant's germination and growth, nutrition, as well as stress protection. However, human activities in the Anthropocene are linked to a significant shift of diversity, evenness and specificity of the plant microbiota. In addition, and very importantly, many plant symbionts are missing or no longer functional. It will require targeted microbiome management to support and reintroduce them. In future agriculture, we should aim at replacing harmful chemicals in the field, as well as post-harvest, by using precision microbiome engineering. This is because the plant microbiome is connected across systems and crucial for human and planetary health. This commentary aims to inspire holistic studies for the development of solutions for sustainable agriculture in framework of the One Health and the Planetary Health concepts.

Despite evidence that the microbiome extends host genetic and phenotypic traits, information on how the microbiome is transmitted and maintained across generations remains fragmented. For seed-bearing plants, seeds harbor a distinct microbiome and play a unique role by linking one generation to the next. Studies on microbial inheritance, a process we suggest including both vertical transmission and the subsequent migration of seed microorganisms to the new plant, thus become essential for our understanding of host evolutionary potential and host-microbiome coevolution. We propose dividing the inheritance process into three stages: (i) plant to seed, (ii) seed dormancy, and (iii) seed to seedling. We discuss the factors affecting the assembly of the microbiome during the three stages, highlight future research directions, and emphasize the implications of microbial inheritance for fundamental science and society.

Abstract Background A detailed understanding of antimicrobial resistance trends among all human-related environments is key to combat global health threats. In food science, however, the resistome is still little considered. Here, we studied the apple microbiome and resistome from different cultivars (Royal Gala and Braeburn) and sources (freshly harvested in South Africa and exported apples in Austrian supermarkets) by metagenomic approaches, genome reconstruction and isolate sequencing. Results All fruits harbor an indigenous, versatile resistome composed of 132 antimicrobial resistance genes (ARGs) encoding for 19 different antibiotic classes. ARGs are partially of clinical relevance and plasmid-encoded; however, their abundance within the metagenomes is very low (≤ 0.03%). Post-harvest, after intercontinental transport, the apple microbiome and resistome was significantly changed independently of the cultivar. In comparison to fresh apples, the post-harvest microbiome is characterized by higher abundance of Enterobacteriales, and a more diversified pool of ARGs, especially associated with multidrug resistance, as well as quinolone, rifampicin, fosfomycin and aminoglycoside resistance. The association of ARGs with metagenome-assembled genomes (MAGs) suggests resistance interconnectivity within the microbiome. Bacterial isolates of the phyla Gammaproteobacteria, Alphaproteobacteria and Actinobacteria served as representatives actively possessing multidrug resistance and ARGs were confirmed by genome sequencing. Conclusion Our results revealed intrinsic and potentially acquired antimicrobial resistance in apples and strengthen the argument that all plant microbiomes harbor diverse resistance features. Although the apple resistome appears comparatively inconspicuous, we identified storage and transport as potential risk parameters to distribute AMR globally and highlight the need for surveillance of resistance emergence along complex food chains.

Seed microbiota influence germination and plant health and have the potential to improve crop performance, but the factors that determine their structure and functions are still not fully understood. Here, we analysed the impact of plant-related and external factors on seed endophyte communities of 10 different oilseed rape (Brassica napus L.) cultivars from 26 field sites across Europe. All seed lots harboured a high abundance and diversity of endophytes, which were dominated by six genera: Ralstonia, Serratia, Enterobacter, Pseudomonas, Pantoea, and Sphingomonas. The cultivar was the main factor explaining the variations in bacterial diversity, abundance and composition. In addition, the latter was significantly influenced by diverse biotic and abiotic factors, for example host germination rates and disease resistance against Plasmodiophora brassicae. A set of bacterial biomarkers was identified to discriminate between characteristics of the seeds, for example Sphingomonas for improved germination and Brevundimonas for disease resistance. Application of a Bayesian community approach suggested vertical transmission of seed endophytes, where the paternal parent plays a major role and might even determine the germination performance of the offspring. This study contributes to the understanding of seed microbiome assembly and underlines the potential of the microbiome to be implemented in crop breeding and biocontrol programmes.