Challenges of metagenomics and single-cell genomics approaches for exploring cyanobacterial diversity

Transdisciplinary approaches for the study of cyanobacteria and cyanotoxins

Cyanobacteria, ancient aerobic and photoautotrophic prokaryotes, thrive in diverse ecosystems due to their extensive morphological and physiological adaptations. They play crucial roles in aquatic ecosystems as primary producers and resource providers but also pose significant ecological and health risks through blooms that produce harmful toxins, called cyanotoxins. The taxonomic affiliation of cyanobacteria has evolved from morphology-based methods to genomic analysis, which offers detailed structural and physiological insights that are essential for accurate taxonomic affiliation and monitoring. However, challenges posed by uncultured species have been extrapolated to the detection and quantification of cyanotoxins. Current advances in molecular biology and informatics improve the precision of monitoring and allow the analysis of groups of genes related to toxin production, providing crucial information for environmental biosafety and public health. Unfortunately, public genomic databases heavily underrepresent cyanobacteria, which limits the understanding of their diversity and metabolic capabilities. Despite the increasing availability of cyanobacterial genome sequences, research is still largely focused on a few model strains, narrowing the scope of genetic and metabolic studies. The challenges posed by cyanobacterial blooms and cyanotoxins necessitate improved molecular, cultivation, and polyphasic techniques for comprehensive classification and quantification, highlighting the need for advanced genomic approaches to better understand and manage cyanobacteria and toxins. This review explores the application of transdisciplinary approaches for the study of cyanobacteria and cyanotoxins focused on diversity analysis, population quantification, and cyanotoxin monitoring, emphasizing their genomic resources and their potential in the genomic mining of toxin-related genes.

DRAGoM: Classification and Quantification of Noncoding RNA in Metagenomic Data

Noncoding RNAs (ncRNAs) play important regulatory and functional roles in microorganisms, such as regulation of gene expression, signaling, protein synthesis, and RNA processing. Hence, their classification and quantification are central tasks toward the understanding of the function of the microbial community. However, the majority of the current metagenomic sequencing technologies generate short reads, which may contain only a partial secondary structure that complicates ncRNA homology detection. Meanwhile, de novo assembly of the metagenomic sequencing data remains challenging for complex communities. To tackle these challenges, we developed a novel algorithm called DRAGoM (Detection of RNA using Assembly Graph from Metagenomic data). DRAGoM first constructs a hybrid graph by merging an assembly string graph and an assembly de Bruijn graph. Then, it classifies paths in the hybrid graph and their constituent readsinto differentncRNA families based on both sequence and structural homology. Our benchmark experiments show that DRAGoMcan improve the performance and robustness over traditional approaches on the classification and quantification of a wide class of ncRNA families.

Single-cell identification by microfluidic-based in situ extracting and online mass spectrometric analysis of phospholipids expression

This work describes a microfluidic system for in situ extraction of a single-cell and its phosphatidylcholine analysis through mass spectrometry. This approach uncovered cellular heterogeneity among seemingly identical cells and provided a new platform for identification and classification of cells.

In Situ Scatheless Cell Detachment Reveals Correlation between Adhesion Strength and Viability at Single-Cell Resolution

Single-cell biology provides insights into some of the most fundamental processes in biology and promotes the understanding of life's mysteries. As the technologies to study single-cells expand, they will require sophisticated analytical tools to make sense of various behaviors and components of single-cells as well as their relations in the adherent tissue culture. In this paper, we revealed cell heterogeneity and uncovered the connections between cell adhesion strength and cell viability at single-cell resolution by extracting single adherent cells of interest from a standard tissue culture by using a microfluidic chip-based live single-cell extractor (LSCE). We believe that this method will provide a valuable new tool for single-cell biology.

A Metagenomic Approach to Cyanobacterial Genomics

Cyanobacteria, or oxyphotobacteria, are primary producers that establish ecological interactions with a wide variety of organisms. Although their associations with eukaryotes have received most attention, interactions with bacterial and archaeal symbionts have also been occurring for billions of years. Due to these associations, obtaining axenic cultures of cyanobacteria is usually difficult, and most isolation efforts result in unicyanobacterial cultures containing a number of associated microbes, hence composing a microbial consortium. With rising numbers of cyanobacterial blooms due to climate change, demand for genomic evaluations of these microorganisms is increasing. However, standard genomic techniques call for the sequencing of axenic cultures, an approach that not only adds months or even years for culture purification, but also appears to be impossible for some cyanobacteria, which is reflected in the relatively low number of publicly available genomic sequences of this phylum. Under the framework of metagenomics, on the other hand, cumbersome techniques for achieving axenic growth can be circumvented and individual genomes can be successfully obtained from microbial consortia. This review focuses on approaches for the genomic and metagenomic assessment of non-axenic cyanobacterial cultures that bypass requirements for axenity. These methods enable researchers to achieve faster and less costly genomic characterizations of cyanobacterial strains and raise additional information about their associated microorganisms. While non-axenic cultures may have been previously frowned upon in cyanobacteriology, latest advancements in metagenomics have provided new possibilities for in vitro studies of oxyphotobacteria, renewing the value of microbial consortia as a reliable and functional resource for the rapid assessment of bloom-forming cyanobacteria.