Characterizing the microbiomes of Antarctic sponges: a functional metagenomic approach

AbstractXylanases are widely used enzymes in the food, textile, and paper industries. Most efficient xylanases have been identified from lignocellulose-degrading microbiota, such as the microbiota of the cow rumen and the termite hindgut. Xylanase genes from efficient pulp and paper wastewater treatment (PPWT) microbiota have been previously recovered by metagenomics, assigning most of the xylanase genes to the GH10 family. In this study, a total of 40 GH10 family xylanase genes derived from a certain PPWT microbiota were cloned and expressed in Escherichia coli BL21 (DE3). Among these xylanase genes, 14 showed xylanase activity on beechwood substrate. Two of these, PW-xyl9 and PW-xyl37, showed high activities, and were purified to evaluate their xylanase properties. Values of optimal pH and temperature for PW-xyl9 were pH 7 and 60 ℃, respectively, while those for PW-xyl37 were pH 7 and 55 ℃, respectively; their specific xylanase activities under optimal conditions were 470.1 U/mg protein and 113.7 U/mg protein, respectively. Furthermore, the Km values of PW-xyl9 and PW-xyl37 were determined as 8.02 and 18.8 g/L, respectively. The characterization of these two xylanases paves the way for potential application in future pulp and paper production and other industries, indicating that PPWT microbiota has been an undiscovered reservoir of efficient lignocellulase genes. This study demonstrates that a metagenomic approach has the potential to screen efficient xylanases of uncultured microorganisms from lignocellulose-degrading microbiota. In a similar way, other efficient lignocellulase genes might be identified from PPWT treatment microbiota in the future.

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Evolutionarily recent dual obligatory symbiosis among adelgids indicates a transition between fungus- and insect-associated lifestyles

The ISME Journal ◽

10.1038/s41396-021-01056-z ◽

2021 ◽

Author(s):

Gitta Szabó ◽

Frederik Schulz ◽

Alejandro Manzano-Marín ◽

Elena Rebecca Toenshoff ◽

Matthias Horn

Keyword(s):

Defense Mechanisms ◽

Amino Acid Production ◽

Evolutionary Transition ◽

Evolutionary Time ◽

Evolutionary Trajectories ◽

Host Infection ◽

Phylogenomic Analyses ◽

Time Specific ◽

High Level ◽

Metagenomic Approach

AbstractAdelgids (Insecta: Hemiptera: Adelgidae) form a small group of insects but harbor a surprisingly diverse set of bacteriocyte-associated endosymbionts, which suggest multiple replacement and acquisition of symbionts over evolutionary time. Specific pairs of symbionts have been associated with adelgid lineages specialized on different secondary host conifers. Using a metagenomic approach, we investigated the symbiosis of the Adelges laricis/Adelgestardus species complex containing betaproteobacterial (“Candidatus Vallotia tarda”) and gammaproteobacterial (“Candidatus Profftia tarda”) symbionts. Genomic characteristics and metabolic pathway reconstructions revealed that Vallotia and Profftia are evolutionary young endosymbionts, which complement each other’s role in essential amino acid production. Phylogenomic analyses and a high level of genomic synteny indicate an origin of the betaproteobacterial symbiont from endosymbionts of Rhizopus fungi. This evolutionary transition was accompanied with substantial loss of functions related to transcription regulation, secondary metabolite production, bacterial defense mechanisms, host infection, and manipulation. The transition from fungus to insect endosymbionts extends our current framework about evolutionary trajectories of host-associated microbes.

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Granulicatella Adiacens as an Unusual Cause of Microbial Keratitis: A Metagenomic Approach

Ocular Immunology and Inflammation ◽

10.1080/09273948.2021.1933066 ◽

2021 ◽

pp. 1-2

Author(s):

Davide Borroni

Keyword(s):

Microbial Keratitis ◽

Granulicatella Adiacens ◽

Metagenomic Approach

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Silicon isotopes in Antarctic sponges: an interlaboratory comparison

Antarctic Science ◽

10.1017/s0954102010000593 ◽

2010 ◽

Vol 23 (1) ◽

pp. 34-42 ◽

Cited By ~ 30

Author(s):

Katharine R. Hendry ◽

Melanie J. Leng ◽

Laura F. Robinson ◽

Hilary J. Sloane ◽

Jerzy Blusztjan ◽

...

Keyword(s):

Southern Ocean ◽

Matrix Effects ◽

Global Climate ◽

Intermediate Water ◽

Silicon Isotopes ◽

Important Player ◽

Si Isotopes ◽

Si Isotope ◽

Additional Reference ◽

Antarctic Sponges

AbstractCycling of deepwater silicon (Si) within the Southern Ocean, and its transport into other ocean basins, may be an important player in the uptake of atmospheric carbon, and global climate. Recent work has shown that the Si isotope (denoted by δ29Si or δ30Si) composition of deep sea sponges reflects the availability of dissolved Si during growth, and is a potential proxy for past deep and intermediate water silicic acid concentrations. As with any geochemical tool, it is essential to ensure analytical precision and accuracy, and consistency between methodologies and laboratories. Analytical bias may exist between laboratories, and sponge material may have matrix effects leading to offsets between samples and standards. Here, we report an interlaboratory evaluation of Si isotopes in Antarctic and sub-Antarctic sponges. We review independent methods for measuring Si isotopes in sponge spicules. Our results show that separate subsamples of non-homogenized sponges measured by three methods yield isotopic values within analytical error for over 80% of specimens. The relationship between δ29Si and δ30Si in sponges is consistent with kinetic fractionation during biomineralization. Sponge Si isotope analyses show potential as palaeoceaongraphic archives, and we suggest Southern Ocean sponge material would form a useful additional reference standard for future spicule analyses.

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