Botryosphaeriaceae gene machinery: Correlation between diversity and virulence

The Botryosphaeriaceae family comprises numerous fungal pathogens capable of causing economically meaningful diseases in a wide range of crops. Many of its members can live as endophytes and turn into aggressive pathogens following the onset of environmental stress events. Their ability to cause disease may rely on the production of a broad set of effectors, such as cell wall-degrading enzymes, secondary metabolites, and peptidases. Here, we conducted comparative analyses of 41 genomes representing six Botryosphaeriaceae genera to provide insights into the genetic features linked to pathogenicity and virulence. We show that these Botryosphaeriaceae genomes possess a large diversity of carbohydrate-active enzymes (CAZymes; 128 families) and peptidases (45 families). Botryosphaeria, Neofusicoccum, and Lasiodiplodia presented the highest number of genes encoding CAZymes involved in the degradation of the plant cell wall components. The genus Botryosphaeria also exhibited the highest abundance of secreted CAZymes and peptidases. Generally, the secondary metabolites gene cluster profile was consistent in the Botryosphaeriaceae family, except for Diplodia and Neoscytalidium. At the strain level, Neofusicoccum parvum NpBt67 stood out among all the Botryosphaeriaceae genomes, presenting a higher number of secretome constituents. In contrast, the Diplodia strains showed the lowest richness of the pathogenicity- and virulence-related genes, which may correlate with their low virulence reported in previous studies. Overall, these results contribute to a better understanding of the mechanisms underlying pathogenicity and virulence in remarkable Botryosphaeriaceae species. Our results also support that Botryosphaeriaceae species could be used as an interesting biotechnological tool for lignocellulose fractionation and bioeconomy.     

Secretome analysis of thermophilic mould Myceliophthora thermophila cultivated on rice straw and hydrolysis of lignocellulosic biomass for bioethanol production

Abstract

Myceliophthora thermophila encodes for large number of carbohydrate-active enzymes (CAZymes) involved in lignocellulosic biomass degradation. The mould was grown on rice straw in solid state fermentation at pH 5.0 and 45?°C that produced high levels of cellulolytic and xylanolytic enzymes i.e. 2218.12, 515.23, 478.23, 13.34?U/g DMR for xylanase, CMCase, FPase and β-glucosidase, respectively. The secretome analysis of M. thermophila BJAMDU5 by mass spectroscopy, described 124 different proteins with majority of CAZymes consisting of glycosyl hydrolases (GH), lytic polysaccharide mono-oxygenases (LPMO), carbohydrate esterases (CE) and polysaccharide lyases (PL). Furthermore, the enzyme cocktail of the mould was evaluated for hydrolysis of steam treated rice straw that produced 184.59?mg/g substrate reducing sugars after 24?h, which was used for production of bioethanol by using fast fermenting yeast Saccharomyces cerevisiae resulting in high production of bioethanol.     

Carbon utilization and growth-inhibition of citrus-colonizing Phyllosticta species

The genus Phyllosticta includes both endophytic and phytopathogenic species that occur on a broad range of plant hosts, including Citrus. Some pathogenic species cause severe disease, such as Phyllosticta citricarpa, the causal agent of Citrus Black Spot (CBS). In contrast, other species, such as Phyllosticta capitalensis, have an endophytic lifestyle in numerous plant hosts. Carbon utilization capabilities are hypothesized to influence both host range and lifestyle, and are in part determined by the set of Carbohydrate Active Enzyme (CAZyme) encoding genes of a species. In this study, carbon utilization capabilities of five Phyllosticta species were determined, as well as the CAZyme repertoire (CAZome) encoded in their genomes. Little variation was found among species in terms of carbon utilization capabilities and CAZome. However, one of the tested carbon sources, sugar beet pulp (SBP), inhibited growth of the plant pathogens, also when combined with another carbon source, while endophytic species remained unaffected.     

Culturable and metagenomic approaches of wheat bran and wheat straw phyllosphere’s highlight new lignocellulolytic microorganisms

The phyllosphere, defined as the aerial parts of plants, is one of the most prevalent microbial habitats on earth. The microorganisms present on the phyllosphere can have several interactions with the plant. The phyllosphere represents then a unique niche where microorganisms have evolved through time in that stressful environment and may have acquired the ability to degrade lignocellulosic plant cell walls in order to survive to oligotrophic conditions. The dynamic lignocellulolytic potential of two phyllospheric microbial consortia (wheat straw and wheat bran) has been studied. The microbial diversity rapidly changed between the native phyllospheres and the final degrading microbial consortia after 48 h of culture. Indeed, the initial microbial consortia was dominated by the Ralstonia (35·8%) and Micrococcus (75·2%) genera for the wheat bran and wheat straw whereas they were dominated by Candidatus phytoplasma (59%) and Acinetobacter (31·8%) in the final degrading microbial consortia respectively. Culturable experiments leading to the isolation of several new lignocellulolytic isolates (belonging to Moraxella and Atlantibacter genera) and metagenomic reconstruction of the microbial consortia highlighted the existence of an unpredicted microbial diversity involved in lignocellulose fractionation but also the existence of new pathways in known genera (presence of CE2 for Acinetobacter, several AAs for Pseudomonas and several GHs for Bacillus in different metagenomes-assembled genomes). The phyllosphere from agricultural co-products represents then a new niche as a lignocellulolytic degrading ecosystem.     

In depth analysis of rumen microbial and carbohydrate-active enzymes profile in Indian crossbred cattle

Rumen houses a plethora of symbiotic microorganisms empowering the host to hydrolyze plant lignocellulose. In this study, NGS based metagenomic approach coupled with bioinformatic analysis was employed to gain an insight into the deconstruction of lignocellulose by carbohydrate-active enzymes (CAZymes) in Indian crossbred Holstein-Friesian cattle. Cattle rumen metagenomic DNA was sequenced using Illumina-MiSeq and 1.9 gigabases of data generated with an average read length of 871 bp. Analysis of the assembled sequences by Pfam-based Carbohydrate-active enzyme Analysis Toolkit identified 17,164 putative protein-encoding CAZymes belonging to different families of glycoside hydrolases (7574), glycosyltransferases (5185), carbohydrate-binding modules (2418), carbohydrate esterases (1516), auxiliary activities (434) and polysaccharide lyases (37). Phylogenetic analysis of putative CAZymes revealed that a significant proportion of CAZymes were contributed by bacteria belonging to the phylum Bacteroidetes (40%), Firmicutes (30%) and Proteobacteria (10%). The comparative analysis of HF cross rumen metagenome with other herbivore metagenomes indicated that Indian crossbred cattle rumen is endowed with a battery of CAZymes that may play a central role in lignocellulose deconstruction. The extensive catalog of enzymes reported in our study that hydrolyzes plant lignocellulose biomass, can be further explored for the better feed utilization in ruminants and also for different industrial applications.     

Hybrid Genome Assembly for Predicting Functional Potential of a Novel Streptomyces Strain as Plant Biomass Valorisation Agent

Environmental bioremediation relies heavily on the realized potential of efficient bioremediation agents or microbial strains of interest. Identifying suitable microbial agents for plant biomass waste valorization requires (i) high-quality genome assemblies to predict the full metabolic and functional potential, (ii) accurate mapping of lignocellulose metabolizing enzymes. However, fragmented nature of the sequenced genomes often limits the prediction ability due to breaks occurring in coding sequences. To address these challenges and as part of our ongoing agri-culturomics efforts, we have performed a hybrid genome assembly using Illumina and Nanopore reads with modified assembly protocol, for a novel Streptomyces strain isolated from the rhizosphere niche of green leafy vegetables grown in a commercial urban farm. High-quality genome was assembled with the size of 8.6 Mb in just two contigs with N50 of 8,542,030 and coverage of 383X. This facilitated identification and complete arrangement of approximately 248 CAZymes and 38 biosynthetic gene clusters in the genome. Multiple gene clusters consisting of cellulases and hemicellulases associated with substrate recognition domain were identified in the genome. Genes for lignin, chitin, and even some aromatic compounds degradation were found in the Streptomyces sp. genome which makes it a promising candidate for lignocellulosic waste valorization. Supplementary InformationThe online version contains supplementary material available at 10.1007/s12088-021-00935-5.     

Gut-microbiota-targeted diets modulate human immune status

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