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Effect of photoperiod and temperature on bioproduct production from juvenile sporophytes of Macrocystis pyrifera
No full textThe giant kelp (Macrocystis pyrifera (Linnaeus) C. Agardh 1820) is a habitatforming
brown seaweed in temperate systems with an unexplored potential as a
source of seaweed bioproducts. This study used M. pyrifera sporophytes sourced
in Tasmania, Australia, to investigate the effect of photoperiod and temperature
on growth rates and the nutritional characteristics of the resulting juvenile
biomass. Four cultivation treatments combined growth temperatures of 12 °C,
15 °C, 18 °C with light:dark (L:D) of 12:12 and 16:8 (L:D) photoperiods, (12 °C –
(12:12); 12 °C – (16:8); 15 °C – (12:12); 18 °C – (12:12) to investigate their effect on
the number and size of sporophytes, biomass accumulation and nutritional
composition. After 60 days of cultivation the 12 °C – (12:12) treatment had the
greatest number of juvenile sporophytes, and the greatest biomass of 14 ± 1.3 g
dry weight (DW). The lowest biomass of 1 g DW, was obtained from the 18 °C –
(12:12) treatment. The protein content across all treatments ranged from 16-
22.48% DW, with the 12 °C (12:12) treatment having largest range, then the 12°C
(16:18) treatment was next with 18.48-22.48% DW, and the 15°C (12:12)
treatment had the lowest protein range with 16.48-18% DW. These results are
in the range of protein content previously reported for brown seaweeds of 5-
20%. Total polysaccharide content ranged from 9.6-16.2% DW with the highest
content of 16.2% DW obtained for the 15 °C – (12:12) treatment, and the lowest
total polysaccharide content of 9.6%DWobtained for the 12 °C (16:18) treatment.
After 66 days of cultivation, the highest yield of sulphated polysaccharides of
0.4% DW was obtained for the 12 °C (12:12) treatment. Total fatty acids were
analysed, with the highest polyunsaturated fatty acid content of 60.4% detected
in the 12 °C (12:12) treatment. This study demonstrates that temperature and
photoperiod are factors impacting juvenile sporophyte growth, biomass
accumulation and biochemical composition. The study showed the least
stressed sporophytes produced the most potentially beneficial nutritional or
bioactive profile
Plant community composition and traits modulate the impacts of drought intensity on soil microbial community composition and function
No full textTerrestrial ecosystems are increasingly threatened by extreme drought events. Soil microbial communities are central to terrestrial ecosystem function via their role in regulating biogeochemical cycling. Consequently, the impact of increasingly intense drought events on soil microbial communities will have knock-on effects for how ecosystems cope with climate change. In an outdoor grassland mesocosm experiment, we determined how increasing drought intensity affects bacterial and fungal community composition, and functioning, during and after drought. We also tested whether plant community resource acquisition strategy (fast-versus slow-strategy plant communities), plant community composition, and plant functional traits mediate soil microbial responses to increasing drought intensity. We found that increasing drought intensity markedly shifted bacterial and fungal community composition, and these effects persisted until the end of the experiment (two months after re-wetting). Bacterial and fungal communities that experienced severe droughts did not return to baseline composition, while those that experienced a mild drought did. Microbial community functioning (potential extracellular enzyme activity) was reduced at peak drought and shortly after re-wetting. While drought intensity effects on bacterial or fungal communities were insensitive to plant community resource acquisition strategy, functional group abundance (aboveground biomass of grass or forb plant species) composition (grass:forb ratio) and leaf traits (leaf dry matter content and leaf nitrogen concentration) explained significant variation in bacterial and fungal community composition during and after drought. Notably, plant community leaf dry matter content and soil nitrogen were the key factors mediating the effect of increasing drought intensity on microbial indicator taxa (ASVs). We conclude that increasing drought intensity affects grassland soil microbial communities during and after drought, and this impact is influenced by plant community composition and functional traits
Kefir4All, a citizen science initiative to raise awareness of the roles that microbes play in food fermentation
Full text linkpeer-reviewedMicroorganisms are ubiquitous in nature and are central to human, animal, environmental, and planetary health. They play a particularly important role in the food chain and the production of high-quality, safe, and health-promoting foods, especially fermented foods. This important role is not always apparent to members of the public. Here, we describe Kefir4All, a citizen science project designed to provide the general public with an opportunity to expand their awareness, knowledge, and practical skills relating to microbiology, introduced through the medium of producing fermented food, i.e., milk kefir or water kefir. During the course of Kefir4All, 123 citizen scientists, from second-level school and non-school settings, participated in a study to track changes in the microbial composition of kefirs, by performing and recording details of milk kefir or water kefir fermentations they performed in their homes or schools over the 21-week project. At the start of the study, the citizen scientists were provided with milk or water kefir grains to initiate the fermentations. Both types of kefir grain are semi-solid, gelatinous-like substances, composed of exopolysaccharides and proteins, containing a symbiotic community of bacteria and yeast. The experimental component of the project was complemented by a number of education and outreach events, including career talks and a site visit to our research center (Kefir Day). At the end of the study, a report was provided to each citizen scientist, in which individualized results of their fermenting activities were detailed. A number of approaches were taken to obtain feedback and other insights from the citizen scientists. Evaluations took place before and after the Kefir4All project to gauge the citizen scientist’s self-reported awareness, knowledge, and interest in microbiology and fermented foods. Further insights into the level of citizen science participation were gained through assessing the number of samples returned for analysis and the level of participation of the citizen scientists throughout the project. Notably, the survey results revealed a self-reported, increased interest in, and general knowledge of, science among the Kefir4All citizen scientists after undertaking the project and a willingness to take part in further citizen science projects. Ultimately, Kefir4All represents an example of the successful integration of citizen science into existing education and research systems
Promiscuous, persistent and problematic: insights into current enterococcal genomics to guide therapeutic strategy
Full text linkAbstract
Vancomycin-resistant enterococci (VRE) are major opportunistic pathogens and the causative agents of serious diseases, such as urinary tract infections and endocarditis. VRE strains mainly include species of Enterococcus faecium and E. faecalis which can colonise the gastrointestinal tract (GIT) of patients and, following growth and persistence in the gut, can transfer to blood resulting in systemic dissemination in the body. Advancements in genomics have revealed that hospital-associated VRE strains are characterised by increased numbers of mobile genetic elements, higher numbers of antibiotic resistance genes and often lack active CRISPR-Cas systems. Additionally, comparative genomics have increased our understanding of dissemination routes among patients and healthcare workers. Since the efficiency of currently available antibiotics is rapidly declining, new measures to control infection and dissemination of these persistent pathogens are urgently needed. These approaches include combinatory administration of antibiotics, strengthening colonisation resistance of the gut microbiota to reduce VRE proliferation through commensals or probiotic bacteria, or switching to non-antibiotic bacterial killers, such as bacteriophages or bacteriocins. In this review, we discuss the current knowledge of the genomics of VRE isolates and state-of-the-art therapeutic advances against VRE infections
The detailed analysis of the microbiome and resistome of artisanal blue-veined cheeses provides evidence on sources and patterns of succession linked with quality and safety traits
Full text linkAbstract
Background
Artisanal cheeses usually contain a highly diverse microbial community which can significantly impact their quality and safety. Here, we describe a detailed longitudinal study assessing the impact of ripening in three natural caves on the microbiome and resistome succession across three different producers of Cabrales blue-veined cheese.
Results
Both the producer and cave in which cheeses were ripened significantly influenced the cheese microbiome. Lactococcus and the former Lactobacillus genus, among other taxa, showed high abundance in cheeses at initial stages of ripening, either coming from the raw material, starter culture used, and/or the environment of processing plants. Along cheese ripening in caves, these taxa were displaced by other bacteria, such as Tetragenococcus, Corynebacterium, Brevibacterium, Yaniella, and Staphylococcus, predominantly originating from cave environments (mainly food contact surfaces), as demonstrated by source-tracking analysis, strain analysis at read level, and the characterization of 613 metagenome-assembled genomes. The high abundance of Tetragenococcus koreensis and Tetragenococcus halophilus detected in cheese has not been found previously in cheese metagenomes. Furthermore, Tetragenococcus showed a high level of horizontal gene transfer with other members of the cheese microbiome, mainly with Lactococcus and Staphylococcus, involving genes related to carbohydrate metabolism functions. The resistome analysis revealed that raw milk and the associated processing environments are a rich reservoir of antimicrobial resistance determinants, mainly associated with resistance to aminoglycosides, tetracyclines, and β-lactam antibiotics and harbored by aerobic gram-negative bacteria of high relevance from a safety point of view, such as Escherichia coli, Salmonella enterica, Acinetobacter, and Klebsiella pneumoniae, and that the displacement of most raw milk-associated taxa by cave-associated taxa during ripening gave rise to a significant decrease in the load of ARGs and, therefore, to a safer end product.
Conclusion
Overall, the cave environments represented an important source of non-starter microorganisms which may play a relevant role in the quality and safety of the end products. Among them, we have identified novel taxa and taxa not previously regarded as being dominant components of the cheese microbiome (Tetragenococcus spp.), providing very valuable information for the authentication of this protected designation of origin artisanal cheese.
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Species-specific predation determines the feeding impacts of six soil protist species on bacterial and eukaryotic prey
Full text linkPeer-reviewedPredatory protists play a central role in nutrient cycling and are involved in other ecosystem functions by predating the microbiome. While most soil predatory protist species arguably are bacterivorous, some protist species can prey on eukaryotes. However, studies about soil protist feeding mainly focused on bacteria as prey and rarely tested both bacteria and eukaryotes as potential prey. In this study, we aimed to decipher soil predator–prey interactions of three amoebozoan and three heterolobosean soil protists and potential bacterial (Escherichia coli; 0.5–1.5 µm), fungal (Saccharomyces cerevisiae; 5–7 µm) and protist (Plasmodiophora brassicae; 3–5 µm) prey, either as individual prey or in all their combinations. We related protist performance (relative abundance) and prey consumption (qPCR) to the protist phylogenetic group and volume. We showed that for the six soil protist predators, the most suitable prey was E. coli, but some species also grew on P. brassicae or S. cerevisiae. While protist relative abundances and growth rates depended on prey type in a protist species-specific manner, phylogenetic groups and volume affected prey consumption. Yet we conclude that protist feeding patterns are mainly species-specific and that some known bacterivores might be more generalist than expected, even preying on eukaryotic plant pathogens such as P. brassicae.Horizon 202
Preconditions for Including the Effects of Urease and Nitrification Inhibitors in Emission Inventories
Full text linkPeer-reviewedUrease and nitrification inhibitors can reduce ammonia and greenhouse gas emissions from fertilizers and manure but their effectiveness depends on the conditions under which they are used. Consequently, it is essential for the credibility of emission reductions reported in regulatory emission inventories that their effectiveness is assessed under real-world conditions and not just in the laboratory. Here, we specify the criteria we consider necessary before the effects of inhibitors are included in regulatory emission inventories.Ministerio de Ciencia, Innovación y Universidade
Mushroom dry bubble disease: novel pathogens, and mycoviruses as potential biocontrol agents
No full textDry bubble disease, caused by Lecanicillium fungicola, seriously affects the production of button mushroom (Agaricus bisporus) at a global level. Due to the increasing limitations of chemical pest management, there is high demand for novel, biological means of disease control. Fungal viruses (mycoviruses)have been shown to cause reduced virulence (hypovirulence)in plant pathogenic fungi, as well as Mycogone perniciosa, causal agent of wet bubble disease. The objective of the project ‘Leca-VIR’ is the search for viruses in fungi associated with dry bubble disease and their
evaluation as potential agents to reduce the virulence of L. fungicola. Fifty seven fungal strains originating from dry bubble-affected mushroom crops were identified based on their ITS
(internal transcribed spacer) sequences and tested for the presence of virus-associated double-stranded (ds) RNA elements by cellulose column chromatography, which were subsequently identified by rRNA-depletion RNAsequencing analysis. The fungal cultures were treated with different antiviral agents to eliminate any detected viruses, then the growth and sporulation of the virus-cured derivatives - confirmed by one-step RT-PCR using primers targeting the viral RdRp (RNA-dependent RNA polymerase) sequences - were examined in comparison with the parent cultures.
Most of the examined fungi were confirmed as L. fungicola. However, additional strains belonging to the family Cordycipitaceae, including Simplicillium aogashimaense and Akanthomyces spp., were also identified, and whose association with dry bubble disease has not yet been reported. Viruses were detected in seven L. fungicola and three Akanthomyces strains and were identified as representatives of the viral families, Chrysoviridae (7), Polymycoviridae (3) and Partitiviridae (1). All were successfully eliminated from the fungal cultures. Virus curing was found not no affect fungal growth however, virus-free derivatives of a L. fungicola strain originally infected with a partitivirus and a polymycovirus, produced up to 32-fold higher amounts of conidia compared to the parent culture. The disappearance of the polymycovirus during sub-culturing did not result in altered phenotype therefore, the partitivirus is proposed to play a role in the substantial reduction of
conidium production. As abundant sporulation is essential for the infectivity of pathogenic fungi, these findings suggest that this partitivirus may reduce the virulence of L. fungicola, and therefore be of interest in future studies targeting the biological control of dry bubble disease. Lorant Hatvani has received funding from the Research Leaders 2025 programme co-funded by Teagasc and the
Eu-ropean Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agree-ment number 754380
Investigation of near infrared and Raman fibre optic process sensors for protein determination in milk protein concentrate
No full textThis study investigated the potential of two fibre optic process sensors based on near infrared (NIR) or Raman spectroscopic technology for protein measurement in milk protein concentrate (MPC). Partial least squares (PLS) models were developed using NIR, Raman, and fusion of NIR and Raman spectra data. Calibration models developed were optimized by selecting different spectral pre-treatment methods and spectral regions. Overall, the three optimal models (NIR, Raman, fused NIR and Raman) yielded R2p values >0.9 and RMSEP values in the range of 0.168–0.185 %. The optimised fusion model outperformed all Raman models and had a similar protein prediction accuracy (R2p = 0.911 and RMSEP = 0.178 %) compared to the optimised NIR model (R2p = 0.917 and RMSEP =0.168 %). Results of the study demonstrated that both NIR and Raman process probes can be used as process analytical technology (PAT) tools for inline protein measurements of MPC post membrane filtration
Electrostatic spray drying: A new alternative for drying of complex coacervates
No full textComplex coacervation can be used for controlled delivery of bioactive compounds (i.e., flaxseed oil and quercetin). This study investigated the co-encapsulation of flaxseed oil and quercetin by complex coacervation using soluble pea protein (SPP) and gum arabic (GA) as shell materials, followed by innovative electrostatic spray drying (ES). The dried system was analyzed through encapsulation efficiency (EE) and yield (EY), morphological and physicochemical properties, and stability for 60 days. Small droplet size emulsions were produced by GA (in the first step of complex coacervation) due to its greater emulsifying activity than SPP. Oil EY and EE, moisture, and water activity in dried compositions ranged from 75.7 to 75.6, 76.0–73.4 %, 3.4–4.1 %, and 0.1–0.2, respectively. Spherical microcapsules were created with small and aggregated particle size but stable for 60 days. An amount of 8 % of quercetin remained in the dried coacervates after 60 days, with low hydroperoxide production. In summary, when GA is used as the emulsifier and SPP as the second biopolymer in the coacervation process, suitable coacervates for food applications are obtained, with ES being a novel alternative to obtain coacervates in powder, with improved stability for encapsulated compounds. As a result, this study helps provide a new delivery system option and sheds light on how the characteristics of biopolymers and the drying process affect coacervate formation