Genomic and Transcriptomic Evidence for Carbohydrate Consumption among Microorganisms in a Cold Seep Brine Pool

The detailed lifestyle of microorganisms in deep-sea brine environments remains largely unexplored. Using a carefully calibrated genome binning approach, we reconstructed partial to nearly-complete genomes of 51 microorganisms in biofilms from the Thuwal cold seep brine pool of the Red Sea. The recovered metagenome-assembled genomes (MAGs) belong to six different phyla: Actinobacteria, Proteobacteria, Candidatus Cloacimonetes, Candidatus Marinimicrobia, Bathyarchaeota and Thaumarchaeota. By comparison with close relatives of these microorganisms, we identified a number of unique genes associated with organic carbon metabolism and energy generation. These genes included various glycoside hydrolases, nitrate and sulfate reductases, putative bacterial microcompartment biosynthetic clusters (BMC), and F420H2 dehydrogenases. Phylogenetic analysis suggested that the acquisition of these genes probably occurred through horizontal gene transfer (HGT). Metatranscriptomics illustrated that glycoside hydrolases are among the most highly expressed genes. Our results suggest that the microbial inhabitants are well adapted to this brine environment, and anaerobic carbohydrate consumption mediated by glycoside hydrolases and electron transport systems (ETSs) is a dominant process performed by microorganisms from various phyla within this ecosystem

Small and mighty: adaptation of superphylum Patescibacteria to groundwater environment drives their genome simplicity.

BackgroundThe newly defined superphylum Patescibacteria such as Parcubacteria (OD1) and Microgenomates (OP11) has been found to be prevalent in groundwater, sediment, lake, and other aquifer environments. Recently increasing attention has been paid to this diverse superphylum including > 20 candidate phyla (a large part of the candidate phylum radiation, CPR) because it refreshed our view of the tree of life. However, adaptive traits contributing to its prevalence are still not well known.ResultsHere, we investigated the genomic features and metabolic pathways of Patescibacteria in groundwater through genome-resolved metagenomics analysis of > 600 Gbp sequence data. We observed that, while the members of Patescibacteria have reduced genomes (~ 1 Mbp) exclusively, functions essential to growth and reproduction such as genetic information processing were retained. Surprisingly, they have sharply reduced redundant and nonessential functions, including specific metabolic activities and stress response systems. The Patescibacteria have ultra-small cells and simplified membrane structures, including flagellar assembly, transporters, and two-component systems. Despite the lack of CRISPR viral defense, the bacteria may evade predation through deletion of common membrane phage receptors and other alternative strategies, which may explain the low representation of prophage proteins in their genomes and lack of CRISPR. By establishing the linkages between bacterial features and the groundwater environmental conditions, our results provide important insights into the functions and evolution of this CPR group.ConclusionsWe found that Patescibacteria has streamlined many functions while acquiring advantages such as avoiding phage invasion, to adapt to the groundwater environment. The unique features of small genome size, ultra-small cell size, and lacking CRISPR of this large lineage are bringing new understandings on life of Bacteria. Our results provide important insights into the mechanisms for adaptation of the superphylum in the groundwater environments, and demonstrate a case where less is more, and small is mighty

The Light Chain Domain and Especially the C-Terminus of Receptor-Binding Domain of the Botulinum Neurotoxin (BoNT) Are the Hotspots for Amino Acid Variability and Toxin Type Diversity

Botulinum neurotoxins (BoNT) are the most potent toxins in the world. They are produced by a few dozens of strains within several clostridial species. The toxin that they produce can cause botulism, a flaccid paralysis in humans and other animals. With seven established serologically different types and over 40 subtypes, BoNTs are among the most diverse known toxins. The toxin, its structure, its function and its physiological effects on the neural cell and animal hosts along with its diversity have been the subjects of numerous studies. However, many gaps remain in our knowledge about the BoNT toxin and the species that produce them. One of these gaps involves the distribution and extent of variability along the full length of the gene and the protein as well as its domains and subdomains. In this study, we performed an extensive analysis of all of the available 143 unique BoNT-encoding genes and their products, and we investigated their diversity and evolution. Our results indicate that while the nucleotide variability is almost uniformly distributed along the entire length of the gene, the amino acid variability is not. We found that most of the differences were concentrated along the protein’s light chain (LC) domain and especially, the C-terminus of the receptor-binding domain (HCC). These two regions of the protein are thus identified as the main source of the toxin type differentiation, and consequently, this toxin’s versatility to bind different receptors and their isoforms and act upon different substrates, thus infecting different hosts

Pseudovibrio hongkongensis sp nov., isolated from a marine flatworm

A Gram-negative, motile, rod-shaped bacterial strain, designated UST20140214-015B(T), was isolated from a marine flatworm (Polyclad). The bacterium was found to be Gram-negative, oxidase and catalase positive, long-rod shaped, and motile by means of several peritrichous or subpolar flagella. Strain UST20140214-015B(T) grew optimally at 28 A degrees C, at pH 7.0 and in the presence of 3 % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain UST20140214-015B(T) belongs to the genus Pseudovibrio, with highest sequence similarity to Pseudovibrio japonicus WSF2(T) (96.9 %), followed by P. ascidiaceicola F423(T) (96.7 %), P. denitrificans DN34(T) (96.6 %), P. axinellae Ad2(T) (96.3 %). All the other species shared < 95.5 % sequence similarity. The principal fatty acids were identified as summed feature 8 (C-18:1 omega 7c/omega 6c, as defined by the MIDI system; 70.8 %), C-16:0 (9.1 %), summed feature 3 (C-16:1 omega 6c/C-16:1 omega 7c; 5.7 %). The G+C content of the chromosomal DNA was determined to be 53.3 mol%. The combined genotypic and phenotypic data show that strain UST20140214-015B(T) represents a novel species within the genus Pseudovibrio, for which the name Pseudovibrio hongkongensis sp. nov. is proposed, with the type strain UST20140214-015B(T) (=KCTC 42383(T) = MCCC 1K00451(T))

Internalization of myriocin involved in energy and affected expression of genes and proteins in the endocytosis pathway in Fusarium oxysporum f. sp. niveum

AbstractMyriocin, isolated from Bacillus amyloliquefaciens LZN01, can inhibit the growth of Fusarium oxysporum f. sp. niveum (Fon) by inducing membrane damage and targeting intracellular molecules. In the present study, the mechanism of myriocin entry into Fon cells was investigated. Fluorescence images demonstrated that internalization of myriocin was decreased by low temperature, NaN3 and Brefeldin A. The mechanism of myriocin entry into Fon cells was revealed by analyses of transcriptome and proteome. A total of 422 common differentially expressed genes (DEGs) were identified. Most of DEGs were assigned to transport and catabolism, folding, sorting and degradation, and enrichment analysis of some DEGs was closely related to transmembrane transport and vesicle transport. The combined analysis between the transcriptome and proteome showed that the expression levels of some related genes and proteins, mainly those related to oxidative phosphorylation, ABC transporters, micro chromosome maintenance protein, adaptor proteins etc., were affected. The DEGs were further verified by reverse transcription quantitative polymerase chain reaction (RT-qPCR). In conclusion, myriocin’s entry into Fon cells depended partially on energy and involved endocytosis, and the expression of certain genes and proteins was affected

De novo transcriptome assembly and positive selection analysis of an individual deep-sea fish

http://www.godac.jamstec.go.jp/darwin/cruise/kairei/kr15-17/

The intestinal microbiome of an Indo-Pacific humpback dolphin (Sousa chinensis) stranded near the Pearl River Estuary, China

The mammalian intestinal microbiome is critical for host health and disease resistance. However, the cetacean intestinal microbiota remains relatively unexplored. By using high-throughput 16S rRNA gene sequencing, we analyzed intestinal bacterial samples from an Indo-pacific humpback dolphin (Sousa chinensis) stranded near the Pearl River Estuary in China. The samples included 3 anatomical regions (foregut, midgut, and rectum) and 2 anatomical locations (content and mucus). Our analyses revealed that the dolphin intestinal bacteria contained 139 operational taxonomic units (OTUs), dominated at the phyla level byFirmicutes(47.05% in the content; 94.77% in the mucus), followed byBacteroidetes(23.63% in the content; 1.58% in the mucus) andGammaproteobacteria(14.82% in the content; 2.05% in the mucus). The intestinal bacteria had a small core community (15 OTUs, accounting for 99.74% of the reads), some of which could be potentially pathogenic to both human and dolphins. As an alternative to sampling the dolphin intestinal bacteria, fecal sampling could be used. Additionally, function potentials such as, xenobiotics biodegradation, beta-lactam resistance, and human disease-related pathways, were detected in the dolphin intestinal bacteria. These findings provide the first baseline knowledge of the intestinal microbiome of the Indo-Pacific humpback dolphin, which may offer new insights into cetacean conservation by using microbial surveillance