The car tank lid bacteriome: a reservoir of bacteria with potential in bioremediation of fuel

Bioremediation of petroleum refinery wastewater by fungal stains isolated from the fishing harbour of Bizerte (Mediterranean Sea)

The study was conducted in order to explore the potential of fungi isolated from surface and bottom seawater collected from the fishing harbour of Bizerte on the bioremediation of industrial effluent (IE) contaminated by petroleum hydrocarbon. Among the 128 fungal isolates, 11 were isolated from surface seawater and 7 from bottom seawater, representing 18 taxa in total. The gas chromatography mass spectrometry (GC-MS) was used for the determination of hydrocarbon compounds in IE. An initial screening of fungal growth using six concentrations ranged between 20 and 70% (v/v) IE has allowed the identification of the optimal concentration for fungal growth as well as selection of species able to tolerate high amounts of hydrocarbon. Colorimetric test employing 2,6-dichlorophenol indophenol and gravimetric method was applied for the assessment of fungal growth using 20% EI. By checking the phylogenetic affiliation of the high-performing stains as identified using ITSr DNA sequence, a dominance of Ascomycetes was detected. Indeed, Aspergillus terreus and Penicillium expansum may degrade 82.07 and 81.76% of residual total petroleum hydrocarbon (TPH), respectively. Both species were collected from surface seawater. While, Aspergillus niger, Colletotrichum sp and Fusarium annulatum displayed comparable degradation rates 40.43%, 41.3%, and 42.03%, respectively. The lowest rate of degradation 33.62% was detected in Emericellopsis phycophila. All those species were isolated from bottom seawater, excepting A. niger isolated from surface water. This work highlighted the importance of exploring the potential of fungi isolated from the natural environment on the bioremediation of industrial effluent. Our results promoted the investigation of the potential of the high-performing isolates A. terreus and P. expansum on the bioremediation of IE at pilot-scale and then in situ.

Plant neopolyploidy and genetic background differentiate the microbiome of duckweed across a variety of natural freshwater sources

Whole-genome duplication has long been appreciated for its role in driving phenotypic novelty in plants, often altering the way organisms interface with the abiotic environment. Only recently, however, have we begun to investigate how polyploidy influences interactions of plants with other species, despite the biotic niche being predicted as one of the main determinants of polyploid establishment. Nevertheless, we lack information about how polyploidy affects the diversity and composition of the microbial taxa that colonize plants, and whether this is genotype-dependent and repeatable across natural environments. This information is a first step towards understanding whether the microbiome contributes to polyploid establishment. We, thus, tested the immediate effect of polyploidy on the diversity and composition of the bacterial microbiome of the aquatic plant Spirodela polyrhiza using four pairs of diploids and synthetic autotetraploids. Under controlled conditions, axenic plants were inoculated with pond waters collected from 10 field sites across a broad environmental gradient. Autotetraploids hosted 4%-11% greater bacterial taxonomic and phylogenetic diversity than their diploid progenitors. Polyploidy, along with its interactions with the inoculum source and genetic lineage, collectively explained 7% of the total variation in microbiome composition. Furthermore, polyploidy broadened the core microbiome, with autotetraploids having 15 unique bacterial taxa in addition to the 55 they shared with diploids. Our results show that whole-genome duplication directly leads to novelty in the plant microbiome and importantly that the effect is dependent on the genetic ancestry of the polyploid and generalizable over many environmental contexts.

A comprehensive study on diesel oil bioremediation under microcosm conditions using a combined microbiological, enzymatic, mass spectrometry, and metabarcoding approach

This study aims at the application of a marine fungal consortium (Aspergillus sclerotiorum CRM 348 and Cryptococcus laurentii CRM 707) for the bioremediation of diesel oil-contaminated soil under microcosm conditions. The impact of biostimulation (BS) and/or bioaugmentation (BA) treatments on diesel-oil biodegradation, soil quality, and the structure of the microbial community were studied. The use of the fungal consortium together with nutrients (BA/BS) resulted in a TPH (Total Petroleum Hydrocarbon) degradation 42% higher than that obtained by natural attenuation (NA) within 120 days. For the same period, a 72 to 92% removal of short-chain alkanes (C12 to C19) was obtained by BA/BS, while only 3 to 65% removal was achieved by NA. BA/BS also showed high degradation efficiency of long-chain alkanes (C20 to C24) at 120 days, reaching 90 and 92% of degradation of icosane and heneicosane, respectively. In contrast, an increase in the levels of cyclosiloxanes (characterized as bacterial bioemulsifiers and biosurfactants) was observed in the soil treated by the consortium. Conversely, the NA presented a maximum of 37% of degradation of these alkane fractions. The 5-ringed PAH benzo(a)pyrene, was removed significantly better with the BA/BS treatment than with the NA (48 vs. 38 % of biodegradation, respectively). Metabarcoding analysis revealed that BA/BS caused a decrease in the soil microbial diversity with a concomitant increase in the abundance of specific microbial groups, including hydrocarbon-degrading (bacteria and fungi) and also an enhancement in soil microbial activity. Our results highlight the great potential of this consortium for soil treatment after diesel spills, as well as the relevance of the massive sequencing, enzymatic, microbiological and GC-HRMS analyses for a better understanding of diesel bioremediation.

The Microbiome of Things: Appliances, Machines, and Devices Hosting Artificial Niche-Adapted Microbial Communities

As it is the case with natural substrates, artificial surfaces of man-made devices are home to a myriad of microbial species. Artificial products are not necessarily characterized by human-associated microbiomes; instead, they can present original microbial populations shaped by specific environmental-often extreme-selection pressures. This review provides a detailed insight into the microbial ecology of a range of artificial devices, machines, and appliances, which we argue are specific microbial niches that do not necessarily fit in the "build environment" microbiome definition. Instead, we propose here the Microbiome of Things (MoT) concept analogous to the Internet of Things (IoT) because we believe it may be useful to shed light on human-made, but not necessarily human-related, unexplored microbial niches.