Gene expression of bacterial collagenolytic proteases in root caries

Objective: It is unknown whether bacteria play a role in the collagen matrix degradation that occurs during caries progression. Our aim was to characterize the expression level of genes involved in bacterial collagenolytic proteases in root biofilms with and without caries. Method: we collected samples from active cavitated root caries lesions (RC, n = 30) and from sound root surfaces (SRS, n = 10). Total microbial RNA was isolated and cDNA sequenced on the Illumina Hi-Seq2500. Reads were mapped to 162 oral bacterial reference genomes. Genes encoding putative bacterial collagenolytic proteases were identified. Normalization and differential expression analysis was performed on all metatranscriptomes (FDR8) but none in SRS were Pseudoramibacter alactolyticus [HMPREF0721_RS02020; HMPREF0721_RS04640], Scardovia inopinata [SCIP_RS02440] and Olsenella uli DSM7084 [OLSU_RS02990]. Conclusion: Our findings suggest that the U32 proteases may be related to carious dentine. The contribution of a small number of species to dentine degradation should be further investigated. These proteases may have potential in future biotechnological and medical applications, serving as targets for the development of therapeutic agents

Influence of management practice on the microbiota of a critically endangered species: A longitudinal study of kākāpō chick faeces and associated nest litter

Background: The critically endangered kākāpō is a flightless, nocturnal parrot endemic to Aotearoa New Zealand. Recent efforts to describe the gastrointestinal microbial community of this threatened herbivore revealed a low-diversity microbiota that is often dominated by Escherichia-Shigella bacteria. Given the importance of associated microbial communities to animal health, and increasing appreciation of their potential relevance to threatened species conservation, we sought to better understand the development of this unusual gut microbiota profile. To this end, we conducted a longitudinal analysis of faecal material collected from kākāpō chicks during the 2019 breeding season, in addition to associated nest litter material. Results: Using an experimental approach rarely seen in studies of threatened species microbiota, we evaluated the impact of a regular conservation practice on the developing kākāpō microbiota, namely the removal of faecal material from nests. Artificially removing chick faeces from nests had negligible impact on bacterial community diversity for either chicks or nests (p > 0.05). However, the gut microbiota did change significantly over time as chick age increased (p < 0.01), with an increasing relative abundance of Escherichia-Shigella coli over the study period and similar observations for the associated nest litter microbiota (p < 0.01). Supplementary feeding substantially altered gut bacterial diversity of kākāpō chicks (p < 0.01), characterised by a significant increase in Lactobacillus bacteria. Conclusions: Overall, chick age and hand rearing conditions had the most marked impact on faecal bacterial communities. Similarly, the surrounding nest litter microbiota changed significantly over time since a kākāpō chick was first placed in the nest, though we found no evidence that removal of faecal material influenced the bacterial communities of either litter or faecal samples. Taken together, these observations will inform ongoing conservation and management of this most enigmatic of bird species

Endolithic microbial diversity in sandstone and granite from the McMurdo Dry Valleys, Antarctica

Cryptic microbial communities develop within rocky substrates in Antarctica’s McMurdo Dry Valleys as a stress avoidance strategy. They may be cryptoendolithic within pore spaces of weathered rocks, or develop in cracks and fissures as chasmoendolithic communities and are characterised by coloured bands of colonisation. Here we used a precision drill to recover fractions from black, white, green and red layers within colonised granite and sandstone. We combined backscattered scanning electron microscopy and high-throughput sequencing to identify major taxa in each band. We confirmed the presence of algal and fungal lichen symbionts, cyanobacteria and free-living algae, plus a diverse heterotrophic bacterial and archaeal component. A clear delineation at the community level was observed. The relatively biodiverse and heterogenous lichen communities occurred in weathered sandstone cliffs, whilst in granite and sandstone boulders, cyanobacterial communities were dominant. Differences between coloured bands of colonisation within each community were less clear. The study demonstrates that endolithic microbial communities can be recovered using a drill technology similar to that planned for the search for endolithic biosignatures on Mars.Research was supported financially by Dr de los Ríos (CTM2012-38222-C02-02 from the MINECO and PRX15/00478 Salvador Madariaga from the MEC, Spain).Peer Reviewe

Microbial biomarker transition in high-altitude sinter mounds from El Tatio(Chile) through different stages of hydrothermal activity

10.3389/fmicb.2018.03350Frontiers in Microbiology10JAN335