Leucobacter soli sp. nov., from soil amended with humic acid

A Gram-positive, non-spore-forming actinobacterium (IMT-300T) was isolated from soil amended with humic acid in Malvern, AL, USA. This soil has been used for 50+years for the cultivation of earthworms for use as fish bait. Based on 16S rRNA gene sequence similarity studies, strain IMT-300T was shown to belong to the genus Leucobacter and was closely related to the type strain of ‘Leucobacter margaritiformis’ L1T (97.8%). Similarity to all other type strains of Leucobacter species was lower than 97.2 %. The average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH) values between the IMT-300T genome assembly and those of the closest relative Leucobacter type strain were 81.4 and 23.3 % ( Leucobacter chironomi ), respectively. The peptidoglycan of strain IMT-300T contained l-2,4-diaminobutyric acid as the diagnostic diamino acid. In addition, glycine, d- and l-alanine and d-glutamic acid were found. The peptidoglycan type represents a variant of B2δ (B11). The major quinones were menaquinones MK-10 and MK-11. The polar lipid profile consisted of the major lipids diphosphatidylglycerol, phosphatidylglycerol and moderate to minor amounts of two unidentified phospholipids, two unidentified glycolipids and an unidentified aminophospholipid. The polyamine pattern contained major amounts of spermidine and spermine. Strain IMT-300T contained the major fatty acids C15 : 0 anteiso, C16 : 0 iso and C17 : 0 anteiso, like other members of the genus Leucobacter . The results of ANI and dDDH analyses and physiological and biochemical tests allowed a genotypic and phenotypic differentiation of strain IMT-300T from the most closely related Leucobacter species. Strain IMT-300T represents a novel Leucobacter species, for which we propose the name Leucobacter soli sp. nov., with the type strain IMT-300T (CIP 111803T=DSM 110505T=CCM 9020T=LMG 31600T).

Extending the Cultivation Period of Undaria pinnatifida by Using Regional Strains with Phenotypic Differentiation along the Sanriku Coast in Northern Japan

The Sanriku district is one of the largest Undaria pinnatifida (Wakame) cultivation areas in Japan. However, the production has steadily declined in recent years due to the high retirement rate among fishers. Extending the cultivation period is a potential way to improve productivity by decentralizing the workforce through the production process. We aimed to investigate the phenotypic differentiation between regional strains of U. pinnatifida collected from Matsushima Bay (MAT) and Hirota Bay (HRT) in the Sanriku district through a cultivation trial to verify the application for the purpose of extending the cultivation period. The growth of MAT was better than that of HRT when the cultivation started earlier (i.e., 9 and 19 October 2014); in contrast, HRT outperformed MAT when the cultivation started later (6 November and 12 December 2014). The yield of MAT reached over the standard amount in the Sanriku district in February. On the other hand, the yield of HRT reached over this value in April. Furthermore, the photosynthetic performance and nutrient uptake rates differed between MAT and HRT, indicating that the differences may result in maturation characteristics. According to these results, the combined use of MAT and HRT would be a valuable strategy by which to extend the cultivation period.

Split it up and see: using proxies to highlight divergent inter-populational performances in aquaculture standardised conditions

Background Considering wild inter-populational phenotypic differentiation can facilitate domestication and subsequent production of new species. However, comparing all populations across a species range to identify those exhibiting suitable key traits for aquaculture (KTA; i.e. important for domestication and subsequent production) expressions is not feasible. Therefore, proxies highlighting inter-populational divergences in KTA are needed. The use of such proxies would allow to identify, prior to bioassays, the wild population pairs which are likely to present differentiations in KTA expressions in aquaculture conditions. Here, we assessed the relevance of three alternative proxies: (i) genetic distance, (ii) habitat divergence, and (iii) geographic/hydrologic distances. We performed this evaluation on seven allopatric populations of Perca fluviatilis for which divergences in KTA had already been shown. Results We showed differences in the correlation degree between the alternative proxy-based and KTA-based distance matrices, with the genetic proxy being correlated to the highest number of KTA. However, no proxy was correlated to all inter-populational divergences in KTA. Conclusion For future domestication trials, we suggest using a multi-proxy assessment along with a prioritisation strategy to identify population pairs which are of interest for further evaluation in bioassays.

Re-Evaluation of the Taxonomy of Talaromyces minioluteus

Talaromyces minioluteus belongs to the section Trachyspermi, has a worldwide distribution and has been found on various substrates, especially on various (stored) food commodities and indoor environments. This species is phenotypically and phylogenetically closely related to T. chongqingensis and T. minnesotensis. The phylogenetic and morphological analyses of 37 strains previously identified as T. chongqingensis, T. minnesotensis and T. minioluteus revealed that this clade incudes eight species: the accepted species T. chongqingensis, T. minnesotensis and T. minioluteus, the newly proposed species T. calidominioluteus, T. africanus and T. germanicus, and the new combinations T. gaditanus (basionym Penicillium gaditanum) and T. samsonii (basionym Penicillium samsonii). In this study, we give insight of the phylogenetic relationships and provide detailed descriptions of the species belonging to this clade. Macromorphological features, especially colony growth rates, texture and conidial colors on agar media, are important characters for phenotypic differentiation between species.

Bacterial growth in multicellular aggregates leads to the emergence of complex lifecycles

In response to environmental stresses such as starvation, many bacteria facultatively aggregate into multicellular structures that can attain new metabolic functions and behaviors. Despite the ubiquity and relevance of this form of collective behavior, we lack an understanding of how the spatiotemporal dynamics of aggregate development emerge from cellular physiology. Here, we show that the coupling between growth and spatial gradient formation leads to the emergence of a complex lifecycle, akin to those known for multicellular bacteria. Under otherwise carbon-limited growth conditions, the marine bacterium Vibrio splendidus 12B01 forms multicellular groups to collectively harvest carbon from the brown-algal polysaccharide alginate. This is achieved during growth on dissolved alginate polymer through formation of spherical, clonal clusters of cells that grow up to 40 μm in radius. Clusters develop striking spatial patterning as they grow due to phenotypic differentiation of sub-populations into a 'shell' of static cells surrounding a motile 'core'. Combining in situ measurements of cell physiology with transcriptomics, we show that shell cells express adhesive type IV pili, while motile core cells express carbon storage granules. The emergence of shell and core phenotypes is cued by opposing gradients of carbon and nitrogen that form within cell clusters due to local metabolic activity. Eventually, the shell ruptures, releasing the carbon-storing core, and we show that carbon-storing cells more readily propagate on alginate than non-carbon storing cells. We propose that phenotypic differentiation promotes the resilience of 12B01 groups by enabling clonal groups to grow larger and propagate more effectively. Phenotypic differentiation may be a widespread, but overlooked, strategy among bacteria to enhance resilience in the context of resource limitation.

Low genome-wide divergence between two lizard populations with high adaptive phenotypic differentiation

Usually, adaptive phenotypic differentiation is paralleled by genetic divergence between locally adapted populations. However, adaptation can also happen in a scenario of non-significant genetic divergence due to intense gene flow and/or recent differentiation. While this phenomenon is rarely published, findings on incipient ecologically-driven divergence or isolation by adaptation are relatively common, which could confound our understanding about the frequency at which they actually occur in nature. Here, we explore genome-wide traces of divergence between two populations of the lacertid lizard Psammodromus algirus separated by a 600 m elevational gradient. These populations seem to be differentially adapted to their environments despite showing low levels of genetic differentiation (according to previously studies of mtDNA and microsatellite data). We performed a search for outliers (i.e. loci subject to selection) trying to identify specific loci with FST statistics significantly higher than those expected on the basis of overall, genome-wide estimates of genetic divergence. We find that local phenotypic adaptation (in terms of a wide diversity of characters) was not accompanied by genome-wide differentiation, even when we maximized the chances of unveiling such differentiation at particular loci with FST-based outlier detection tests. Instead, our analyses confirmed the lack of differentiation on the basis of more than 70,000 SNPs, which is concordant with a scenario of local adaptation without any degree of isolation by environment. Our results add evidence to previous studies in which local adaptation does not lead to any kind of isolation (or early stages of ecological speciation), but maintains phenotypic divergence despite the lack of a differentiated genomic background.

Supergenes on Steroids

At the birth of supergenes, the genomic landscape is dramatically re-organized leading to pronounced differences in phenotypes and increased intrasexual diversity. Two of the best-studied supergenes in vertebrates are arguably the inversion polymorphisms on chromosomes 2 and 11 in the white-throated sparrow (Zonotrichia albicollis) and the ruff (Calidris pugnax), respectively. In both species, regions of suppressed recombination determine plumage coloration and social behavioral phenotypes. Despite the apparent lack of gene overlap between these two supergenes, in both cases the alternative phenotypes seem to be driven largely by alterations in steroid hormone pathways. Here, we explore the interplay between genomic architecture and steroid-related genes. Due to the highly pleiotropic effects of such genes and their universal involvement in social behavior and genomic architecture, forces favouring their linkage are likely to have substantial effects on the evolution of behavioral phenotypes, individual fitness, and life history strategies. We propose that the differentiation of steroid-related genes, inside both supergenes, lies at the core of phenotypic differentiation in both of these interesting species.