The structure and diversity of microbial communities in Paederus fuscipes (Coleoptera: Staphylinidae): from ecological paradigm to pathobiome

BACKGROUND

Paederus fuscipes is medically the most famous rove beetle, which causes dermatitis or conjunctivitis in humans, as well as gastrointestinal toxicosis in livestock, via releasing toxic hemolymph containing pederin. Pedrin biosynthesis genes have been identified in uncultured Pseudomonas-like endosymbionts that are speculated to be acquired through a horizontal transfer. However, the composition of the P. fuscipes microbial community, especially of the gut and genital microbiome, remains unclear. This study was aimed to characterize the structure and diversity of P. fuscipes-associated bacterial communities in terms of gender, organ, and location using the Illumina HiSeq platform in the southern littorals of Caspian Sea.

RESULTS

The OTUs identified from P. fuscipes specimens were collapsed into 40 phyla, 112 classes, 249 orders, 365 families, 576 genera, and 106 species. The most abundant families were Pseudomonadaceae, Spiroplasmataceae, Weeksellaceae, Enterococcaceae, and Rhizobiaceae, respectively. Thirty top genera made up > 94% of the P. fuscipes microbiome, with predominating Pseudomonas, followed by the Spiroplasma, Apibacter, Enterococcus, Dysgonomonas, Sebaldella, Ruminococcus, and Wolbachia. Interesting dissimilarities were also discovered within and between the beetle microbiomes in terms of genders and organs. Analyses showed that Spiroplasma / Apibacter as well as Pseudomonas / Pseudomonas were the most abundant in the genitals / intestines of male and female beetles, respectively. Bacterial richness did not display any significant difference in the three provinces but was higher in male beetles than in females and more in the genitals than intestines.

CONCLUSIONS

The present study identified Pseudomonas-like endobacterium as a common symbiont of P. fuscipes beetles; this bacterium begins its journey from gut and genitalia of females to reach the male rove beetles. Additionally, male and female rove beetles were characterized by distinctive microbiota in different organs, likely reflecting different functions and/or adaptation processes. Evidence of the extension of P. fuscipes microbiome from the environmental paradigm to the pathobiome was also presented herein. A comprehensive survey of P. fuscipes microbiome components may eventually lead to ecological insights into the production and utilization of defensive compound of pederin and also the management of linear dermatitis with the use of available antibiotics against bacterial pathogens released by the beetles. Video Abstract.

RMI-DBG algorithm: A more agile iterative de Bruijn graph algorithm in short read genome assembly

The de Bruijn Graph algorithm (DBG) as one of the cornerstones algorithms in short read assembly has extended with the rapid advancement of the Next Generation Sequencing (NGS) technologies and low-cost production of millions of high-quality short reads. Erroneous reads, non-uniform coverage, and genomic repeats are three major problems that influence the performance of short read assemblers. To encounter these problems, the iterative DBG algorithm applies multiple [Formula: see text]-mers instead of a single [Formula: see text]-mer, by iterating the DBG graph over a range of [Formula: see text]-mer sizes from the minimum to the maximum. However, the iteration paradigm of iterative DBG deals with complex graphs from the beginning of the algorithm and therefore, causes more potential errors and computational time for resolving various unreal branches. In this research, we propose the Reverse Modified Iterative DBG graph (named RMI-DBG) for short read assembly. RMI-DBG utilizes the DBG algorithm and String graph to achieve the advantages of both algorithms. We present that RMI-DBG performs faster with comparable results in comparison to iterative DBG. Additionally, the quality of the proposed algorithm in terms of continuity and accuracy is evaluated with some commonly-used assemblers via several real datasets of the GAGE-B benchmark.

Whole genome sequence of Pantoea agglomerans ANP8, a salinity and drought stress-resistant bacterium isolated from alfalfa (Medicago sativa L.) root nodules

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Strain ANP8 was isolated from root nodules of alfalfa grown on saline soil.

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ANP8 has multiple PGP traits and is resistant to salinity and drought stress.

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Complete genome sequence of Pantoea agglomerans ANP8 was presented.

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The growth rate of ANP8 was considerable compared to the growth rate of E. coli.

Environmental abiotic stress conditions, especially drought and salinity, are currently the major factors that reduce crop yields worldwide. It has been reported that plant–associated beneficial bacteria, especially strains resistant to abiotic stresses that could maintain their efficiency under environmental challenging conditions, can contribute to alleviate abiotic stresses of host plants. In this study, we presented the assembly of the whole genome of Pantoea agglomerans ANP8, a plant growth-promoting bacterium resistant to salinity and drought stresses. The draft genome assembly contained 4,713,172 bp with 4586 predicted genes. A primary draft genome with a total of 5,115,548 bp and 1916 contigs was obtained (longest contig length being 485,272 bp and smallest contig being 112 bp). Following assembly upgrades, 68 scaffolds and 70 contigs with lengths ≥ 500 bp and an N50 = 209,657 bp were obtained. Number of 5554 and 5472 open reading frames longer than 50 codons were observed in the direct strand and in the reverse strand, respectively. Due to the multiple plant growth-promoting characteristics of this bacterium, genes involved in various indole-3-acetic acid production pathways, e.g., indole-3-pyruvic acid and indole-3-acetamide pathways, were found in the bacterium's genome. In addition, multiple copies of the gcd gene, most important enzymes involvement in the solubilization of phosphates, glucose dehydrogenase, were also observed in this genome. The study provides new genomic information to help understanding the way of action of a stress-tolerant plant growth–promoting bacterium.

Practical evaluation of 11 de novo assemblers in metagenome assembly

Next Generation Sequencing (NGS) technologies are revolutionizing the field of biology and metagenomic-based research. Since the volume of metagenomic data is typically very large, De novo metagenomic assembly can be effectively used to reduce the total amount of data and enhance quality of downstream analysis, such as annotation and binning. Although, there are many freely available assemblers, but selecting one suitable for a specific goal can be highly challenging. In this study, the performance of 11 well-known assemblers was evaluated in the assembly of three different metagenomes. The results obtained show that metaSPAdes is the best assembler and Megahit is a good choice for conservative assembly strategy. In addition, this research provides useful information regarding the pros and cons of each assembler and the effect of read length on assembly, thereby helping scholars to select the optimal assembler based on their objectives.