Biodiversity of marine microbes is safeguarded by phenotypic heterogeneity in ecological traits

Why, contrary to theoretical predictions, do marine microbe communities harbor tremendous phenotypic heterogeneity? How can so many marine microbe species competing in the same niche coexist? We discovered a unifying explanation for both phenomena by investigating a non-cooperative game that interpolates between individual-level competitions and species-level outcomes. We identified all equilibrium strategies of the game. These strategies represent the probability distribution of competitive abilities (e.g. traits) and are characterized by maximal phenotypic heterogeneity. They are also neutral towards each other in the sense that an unlimited number of species can co-exist while competing according to the equilibrium strategies. Whereas prior theory predicts that natural selection would minimize trait variation around an optimum value, here we obtained a mathematical proof that species with maximally variable traits are those that endure. This discrepancy may reflect a disparity between predictions from models developed for larger organisms in contrast to our microbe-centric model. Rigorous mathematics proves that phenotypic heterogeneity is itself a mechanistic underpinning of microbial diversity. This discovery has fundamental ramifications for microbial ecology and may represent an adaptive reservoir sheltering biodiversity in changing environmental conditions.

Schizochytrium sp. (T18) Oil as a Fish Oil Replacement in Diets for Juvenile Rainbow Trout (Oncorhynchus mykiss): Effects on Growth Performance, Tissue Fatty Acid Content, and Lipid-Related Transcript Expression

In this study, we evaluated whether oil extracted from the marine microbe, Schizochytrium sp. (strain T18), with high levels of docosahexaenoic acid (DHA), could replace fish oil (FO) in diets for rainbow trout (Oncorhynchus mykiss). Three experimental diets were tested: (1) a control diet with fish oil (FO diet), (2) a microbial oil (MO) diet with a blend of camelina oil (CO) referred to as MO/CO diet, and (3) a MO diet (at a higher inclusion level). Rainbow trout (18.8 ± 2.9 g fish−1 initial weight ± SD) were fed for 8 weeks and evaluated for growth performance, fatty acid content and transcript expression of lipid-related genes in liver and muscle. There were no differences in growth performance measurements among treatments. In liver and muscle, eicosapentaenoic acid (EPA) was highest in trout fed the FO diet compared to the MO/CO and MO diets. Liver DHA was highest in trout fed the MO/CO diet compared to the FO and MO diets. Muscle DHA was highest in trout fed the MO and MO/CO diets compared to the FO diet. In trout fed the MO/CO diet, compared to the MO diet, fadsd6b was higher in both liver and muscle. In trout fed the FO or MO/CO diets, compared to the MO diet, cox1a was higher in both liver and muscle, cpt1b1a was higher in liver and cpt1a1a, cpt1a1b and cpt1a2a were higher in muscle. Schizochytrium sp. (T18) oil was an effective source of DHA for rainbow trout.

Research Advantages in Marine Microbial Acetylcholinesterase Inhibitors Against Alzheimer’s Disease: An Overview

Public health is significantly threatened by neurodegenerative disorders, especially Alzheimer's disease (AD). A significant cause of dementia is Alzheimer's disease (AD), accounting for up to 75 percent of all cases of dementia. Degeneration of neurons and synapses, primarily characterized by cholinergic dysfunction, are the pathophysiological processes defined for AD progression. This function makes inhibitors of acetylcholinesterase (AChEi) the main class of drugs commonly used to treat the dementia process of AD. The symptomatic progress of Alzheimer's disease (AD) remains a highly viable target since the cholinergic deficiency is a clear and early finding in AD. More and more marine compounds have been isolated from marine animals for the medicinal treatment of neurological conditions, including Alzheimer's disease (AD). Significant producers of AChEIs are fungi and bacteria. Alkaloids, terpenoids, phenylpropanoids, and steroids are the active components in fermentation products. In this review, we provide an overview of the different marine microbe-derived AChEIs and their producing strains.

Research on innovative marine environmental conservation with no environmental impact using marine bio-cement

According to a growing body of research from scientists all over the world, the Earth is heading towards a global catastrophe. Polar ice caps are melting due to rising global temperatures and there have been many consequences for our oceans. The impact of human activity on the oceans has led to growing acidity of the water, as well as rising sea levels. Pollution and physical damage from human activities such as dredging and shipping have hit marine life hard, reducing animal and plant populations and decreasing species diversity. This reduction in key marine components such as the seaweed beds has a massive impact on other species, causing ripple effects that can be felt by humans. Providing food, shelter and breeding grounds for fish, squid, crustaceans and many other organisms, a decrease in the seaweed forests directly correlates to a reduction in sea life in the area, which affects the marine environment as a whole as well threatening the local fishing industry. Scientists have been trying to tackle this damage to the seaweed beds by developing ways in which to re-seed areas of the seabed. A variety of approaches have been taken to growing new seaweed to restore these habitats, but many of these methods are expensive and labour intensive. Associate Professor Masataka Kusube, from the Department of Applied Chemistry and Biochemistry, National Institute Technology at Wakayama College in Japan, is working with a number of industrial partners, including Mitsui Chemicals Inc. to produce large scale marine microbe cultures by pilot test facility and KYC Machine Industry Co., Ltd. to generate large scale marine bio-cement production, Kusube and his team have developed an innovative material dubbed 'marine bio-cement' to support the growth of eelgrass in the waters surrounding Japan.

Co-occurrence of Fe and P stress in natural populations of the marine diazotroph <i>Trichodesmium</i>

Trichodesmium is a globally important marine microbe that provides fixed nitrogen (N) to otherwise N-limited ecosystems. In nature, nitrogen fixation is likely regulated by iron or phosphate availability, but the extent and interaction of these controls are unclear. From metaproteomics analyses using established protein biomarkers for nutrient stress, we found that iron–phosphate co-stress is the norm rather than the exception for Trichodesmium colonies in the North Atlantic Ocean. Counterintuitively, the nitrogenase enzyme was more abundant under co-stress as opposed to single nutrient stress. This is consistent with the idea that Trichodesmium has a specific physiological state during nutrient co-stress. Organic nitrogen uptake was observed and occurred simultaneously with nitrogen fixation. The quantification of the phosphate ABC transporter PstA combined with a cellular model of nutrient uptake suggested that Trichodesmium is generally confronted by the biophysical limits of membrane space and diffusion rates for iron and phosphate acquisition in the field. Colony formation may benefit nutrient acquisition from particulate and organic sources, alleviating these pressures. The results highlight that to predict the behavior of Trichodesmium, both Fe and P stress must be evaluated simultaneously.

Association of lanthipeptide genes with TnpAREP transposases in marine picocyanobacteria

ABSTRACTLanthipeptides are a family of ribosomally synthesized, post-translationally modified peptides that are widespread among bacteria, typically functioning as antibacterials. The marine picocyanobacteria Prochlorococcus and Synechococcus produce an unusual and diverse set of lanthipeptides of unknown function called prochlorosins. While well-studied model bacteria produce one or two different molecules of this type, a single picocyanobacterium can produce as many as 80; the community of picocyanobacteria in a single milliliter of seawater can collectively encode up to 10,000 prochlorosins. The molecular events that led to this expansion and diversification of the lanthipeptide repertoire in picocyanobacteria – the numerically dominant photosynthesizers in the oceans – is unknown.We present evidence for an unusual association between prochlorosin genes with a single-stranded DNA transposase belonging to the TnpAREP family. The genes co-occur and co-localize across the phylogeny of marine picocyanobacteria forming a distinct association pattern within genomes, most likely resulting from the transposase activity. Given the role of TnpAREP homologs in other bacteria, we propose - based on genomic structures - that they contribute to the creation of the prochlorosin structural diversity through a diversifying recombination mechanism.IMPORTANCEOnly a few mechanisms have been described that promote the diversification of a targeted gene region in bacteria. We present indirect evidence that the TnpAREP transposases associated with prochlorosins in picocyanobacteria could represent a novel such mechanism, and explain the extreme expansion and diversification of prochlorosins in this abundant marine microbe.

Co-occurrence of Fe and P stress in natural populations of the marine diazotroph <i>Trichodesmium</i>

Trichodesmium is a globally important marine microbe that provides fixed nitrogen to otherwise N limited ecosystems. In nature, nitrogen fixation is likely regulated by iron or phosphate availability, but the extent and interaction of these controls is unclear. From metaproteomics analyses using established protein biomarkers for iron and phosphate stress, we found that co-stress is the norm rather than the exception for field Trichodesmium colonies. Counter-intuitively, the nitrogenase enzyme was most abundant under co-stress, consistent with the idea that Trichodesmium has a specific physiological state under nutrient co-stress. Organic nitrogen uptake was observed to occur simultaneously with nitrogen fixation. Quantification of the phosphate ABC transporter PstC combined with a cellular model of nutrient uptake suggested that Trichodesmium is confronted by the biophysical limits of membrane space and diffusion rates for iron and phosphate acquisition. Colony formation may benefit nutrient acquisition from particulate and organic nutrient sources, alleviating these pressures. The results indicate that to predict the behavior of Trichodesmium, we must consider multiple nutrients simultaneously across biogeochemical contexts.

Temporal and spatial dynamics of Bacteria, Archaea and protists in equatorial coastal waters

Singapore, an equatorial island in South East Asia, is influenced by a bi-annual reversal of wind directions which defines two monsoon seasons. We characterized the dynamics of the microbial communities of Singapore coastal waters by collecting monthly samples between February 2017 and July 2018 at four sites located across two straits with different trophic status, and sequencing the V6-V8 region of the small sub-unit ribosomal RNA gene (rRNA gene) of Bacteria, Archaea, and Eukaryota. Johor Strait, which is subjected to wider environmental fluctuations from anthropogenic activities, presented a higher abundance of copiotrophic microbes, including Cellvibrionales and Rhodobacterales. The mesotrophic Singapore Strait, where the seasonal variability is caused by changes in the oceanographic conditions, harboured a higher proportion of typically marine microbe groups such as Synechococcales, Nitrosupumilales, SAR11, SAR86, Marine Group II Archaea and Radiolaria. In addition, we observed seasonal variability of the microbial communities in the Singapore Strait, which was possibly influenced by the alternating monsoon regime, while no seasonal pattern was detected in the Johor Strait.

Temporal dynamics of Bacteria, Archaea and protists in equatorial coastal waters

ABSTRACTSingapore, an equatorial island in South East Asia, is influenced by a bi-annual reversal of wind directions which defines two monsoon seasons. We characterized the dynamics of the microbial communities of Singapore coastal waters by collecting monthly samples between February 2017 and July 2018 at four sites located across two straits with different trophic status, and sequencing the V6-V8 region of the small sub-unit ribosomal RNA gene (rRNA gene) of Bacteria, Archaea, and Eukaryota. Johor Strait, which is subjected to wider environmental fluctuations from anthropogenic activities, presented a higher abundance of copiotrophic microbes, including Cellvibrionales and Rhodobacterales. The mesotrophic Singapore Strait, where the seasonal variability is caused by changes in the oceanographic conditions, harboured a higher proportion of typically marine microbe groups such as Synechococcales, Nitrosupumilales, SAR11, SAR86, Marine Group II Archaea and Radiolaria. In addition, we observed seasonal variability of the microbial communities in the Singapore Strait, which was possibly influenced by the alternating monsoon regime, while no seasonal pattern was detected in the Johor Strait.