Display omitted
•Mining activity of realgar ore resulted in co-contamination of As and Sb.•Mining activity also influenced microbial structure and metabolic potentials.•As and Sb co-contamination ...enriched some As- and Sb-resistant bacteria.•The contamination affected As-related genes, and others about C, N, and S cycling.
Microorganisms can mediate arsenic (As) and antimony (Sb) transformation and thus change the As and Sb toxicity and mobility. The influence of As and Sb on the innate microbiome has been extensively characterized. However, how microbial metabolic potentials are influenced by the As and Sb co-contamination is still ambiguous. In this study, we selected two contrasting sites located in the Shimen realgar mine, the largest realgar mine in Asia, to explore the adaptability and response of the soil microbiome to As and Sb co-contamination and the impact of co-contamination on microbial metabolic potentials. It is observed that the geochemical parameters, including the As and Sb fractions, were the driving forces that reshaped the community composition and metabolic potentials. Bacteria associated with Bradyrhizobium, Nocardioides, Sphingomonas, Burkholderia, and Streptomyces were predicted to be tolerant to high concentrations of As and Sb. Co-occurrence network analysis revealed that the genes related to C fixation, nitrate/nitrite reduction, N fixation, and sulfate reduction were positively correlated with the As and Sb fractions, suggesting that As and Sb biogeochemical cycling may interact with and benefit from C, N, and S cycling. The results suggest that As and Sb co-contamination not only influences As-related genes, but also influences other genes correlated with microbial C, N, and S cycling.
Algae are a component of bait sources for animal aquaculture, and they produce abundant valuable compounds for the chemical industry and human health. With today's fast growing demand for algae ...biofuels and the profitable market for cosmetics and pharmaceuticals made from algal natural products, the genetic engineering of marine algae has been attracting increasing attention as a crucial systemic technology to address the challenge of the biomass feedstock supply for sustainable industrial applications and to modify the metabolic pathway for the more efficient production of high-value products. Nevertheless, to date, only a few marine algae species can be genetically manipulated. In this article, an updated account of the research progress in marine algal genomics is presented along with methods for transformation. In addition, vector construction and gene selection strategies are reviewed. Meanwhile, a review on the progress of bioreactor technologies for marine algae culture is also revisited.
Constraining photosynthetic energy conversion efficiency in nature is challenging. In principle, two yield measurements must be made simultaneously: photochemistry, fluorescence and/or thermal ...dissipation. We constructed two different, extremely sensitive and precise active fluorometers: one measures the quantum yield of photochemistry from changes in variable fluorescence, the other measures fluorescence lifetimes in the picosecond time domain. By deploying the pair of instruments on eight transoceanic cruises over six years, we obtained over 200 000 measurements of fluorescence yields and lifetimes from surface waters in five ocean basins. Our results revealed that the average quantum yield of photochemistry was approximately 0.35 while the average quantum yield of fluorescence was approximately 0.07. Thus, closure on the energy budget suggests that, on average, approximately 58% of the photons absorbed by phytoplankton in the world oceans are dissipated as heat. This extraordinary inefficiency is associated with the paucity of nutrients in the upper ocean, especially dissolved inorganic nitrogen and iron. Our results strongly suggest that, in nature, most of the time, most of the phytoplankton community operates at approximately half of its maximal photosynthetic energy conversion efficiency because nutrients limit the synthesis or function of essential components in the photosynthetic apparatus.
This article is part of the themed issue ‘Enhancing photosynthesis in crop plants: targets for improvement’.
Phycobilisomes (PBSs) are the largest light-harvesting antenna in red algae, and feature high efficiency and rate of energy transfer even in a dim environment. To understand the influence of light on ...the energy transfer in PBSs, two red algae Griffithsia pacifica and Porphyridium purpureum living in different light environment were selected for this research. The energy transfer dynamics in PBSs of the two red algae were studied in time-resolved fluorescence spectroscopy in sub-picosecond resolution. The energy transfer pathways and the related transfer rates were uncovered by deconvolution of the fluorescence decay curve. Four time-components, i.e., 8 ps, 94 ps, 970 ps, and 2288 ps were recognized in the energy transfer in PBSs of G. pacifica, and 10 ps, 74 ps, 817 ps and 1292 ps in P. purpureum. In addition, comparison in energy transfer dynamics between the two red algae revealed that the energy transfer was clearly affected by lighting environment. The findings help us to understand the energy transfer mechanisms of red algae for adaptation to a natural low light environment.
The extensive application of perfluoroalkyl and polyfluoroalkyl substances (PFASs) causes their frequent detection in various environments. In this work, two typical PFASs, perfluorooctanoic acid ...(PFOA) and perfluorooctanesulfonic acid (PFOS), are selected to investigate their effects on soil microorganisms. Microbial community structure and microbe–microbe relationships were investigated by high-throughput sequencing and co-occurrence network analysis. Under 90 days of exposure, the alpha-diversity of soil microbial communities was increased with the PFOS treatment, followed by the PFOA treatment. The exposure of PFASs substantially changed the compositions of soil microbial communities, leading to the enrichment of more PFASs-tolerant bacteria, such as Proteobacteria,
Burkholderiales
, and
Rhodocyclales
. Comparative co-occurrence networks were constructed to investigate the microbe–microbe interactions under different PFASs treatments. The majority of nodes in the PFOA and PFOS networks were associated with the genus
Azospirillum
and
Hydrogenophaga
, respectively. The LEfSe analysis further identified a set of biomarkers in the soil microbial communities, such as
Azospirillum
,
Methyloversatilis
,
Hydrogenophaga
,
Pseudoxanthomonas
, and
Fusibacter
. The relative abundances of these biomarkers were also changed by different PFASs treatments. Functional gene prediction suggested that the microbial metabolism processes, such as nucleotide transport and metabolism, cell motility, carbohydrate transport and metabolism, energy production and conversion, and secondary metabolites biosynthesis transport and catabolism, might be inhibited under PFAS exposure, which may further affect soil ecological services.
Soil contamination due to mining activities is a great concern in China. Although the effects of mining pollution resulting in changes of soil characteristics and the microbiome have been documented, ...studies on the responses of plant root-associated microbial assemblages remain scarce. In this work, we collected bulk soil, rhizosphere soil, and root endosphere samples of
Cyperus rotundus
L (
Cyp
) plants from two Pb/Zn mines, of which, one was abandoned (SL) and the other was active (GD), to investigate the bacterial community responses across different site contamination levels and
Cyp
plant compartments. For comparison, one unpolluted site (SD) was included. Results revealed that soils from the SL and GD sites were seriously contaminated by metal(loid)s, including Pb, Zn, As, and Sb. Bacterial richness and diversity depended on the sampling site and plant compartment. All sample types from the SL site had the lowest bacterial diversities and their bacterial communities also exhibited distinct patterns compared to GD and SD samples. As for the specific sampling site, bacterial communities from the root endosphere exhibited different patterns from those in bulk and rhizosphere soil. Compared to the GD and SD sites, the root endosphere and the rhizosphere soil from the SL site shared core microbes, including
Halomonas
,
Pelagibacterium
, and
Chelativorans
, suggesting that they play key roles in
Cyp
plant survival in such harsh environments.
The use of citric acid (CA) chelator to facilitate metal bioavailability is a promising approach for the phytoextraction of heavy metal contaminants. However, the role of the CA chelator associated ...with arbuscular mycorrhizal fungi (AMF) inoculation on phytoextraction of vanadium (V) has not been studied. Therefore, in this study, a greenhouse pot experiment was conducted to evaluate the combined effect of CA chelator and AMF inoculation on growth performance and V phytoextraction of plants in V-contaminated soil. The experiment was performed via CA (at 0, 5, and 10 mM kg
-1
soil levels) application alone or in combination with AMF inoculation by
Medicago sativa
Linn. (
M. sativa
). Plant biomass, root mycorrhizal colonization, P and V accumulation, antioxidant enzyme activity in plants, and soil chemical speciation of V were evaluated. Results depicted (1) a marked decline in plant biomass and root mycorrhizal colonization in 5- and 10-mM CA treatments which were accompanied by a significant increased V accumulation in plant tissues. The effects could be attributed to the enhanced acid-soluble V fraction transferring from the reducible fraction. (2) The presence of CA significantly enhanced P acquisition while the P/V concentration ratio in plant shoots and roots decreased, owing to the increased V translocation from soil to plant. (3) In both CA-treated soil, AMF-plant symbiosis significantly improved dry weight (31.4–73.3%) and P content (37.3–122.5%) in shoots and roots of
M. sativa
. The combined treatments also showed markedly contribution in reduction of malondialdehyde (MDA) content (12.8–16.2%) and higher antioxidants (SOD, POD, and CAT) activities in the leaves. This suggests their combination could promote growth performance and stimulate antioxidant response to alleviate V stress induced by CA chelator. (4) Taken together, 10 mM kg
-1
CA application and AMF inoculation combination exhibited a higher amount of extracted V both in plant shoots and roots. Thus, citric acid–AMF–plant symbiosis provides a novel remediation strategy for in situ V phytoextraction by
M. sativa
in V-contaminated soil.
Seaweed genetic engineering is a transgenic expression system with unique features compared with those of heterotrophic prokaryotes and higher plants. This study discusses several newly sequenced ...seaweed nuclear genomes and the necessity that research on vector design should consider endogenous promoters, codon optimization, and gene copy number. Seaweed viruses and artificial transposons can be applied as transformation methods after acquiring a comprehensive understanding of the mechanism of viral infections in seaweeds and transposon patterns in seaweed genomes. After cultivating transgenic algal cells and tissues in a photobioreactor, a biosafety assessment of genetically modified (GM) seaweeds must be conducted before open-sea application. We propose a set of programs for the evaluation of gene flow from GM seaweeds to local/geographical environments. The effective implementation of such programs requires fundamentally systematic and interdisciplinary studies on algal physiology and genetics, marine hydrology, reproductive biology, and ecology.
Purpose
Glomalin-related soil protein (GRSP), secreted by arbuscular mycorrhizal fungi (AMF), contributes to heavy metal sequestration in polluted soils and sediments. The objective of this study was ...to investigate metal sequestration by GRSP associated with the plants
Miscanthus sinensis
,
Cyperus rotundus
, and
Pteris vittata
.
Materials and methods
A total of 45 rhizosphere soil and plant root samples were collected from three plants at two Pb/Zn mining polluted and non-polluted sites in China. Soil samples were analyzed for total and bioavailable heavy metal (Cr, Cu, Cd, Pb, Zn, As, Sb, and Ni) concentration, chemical properties (SOC, TN, TP, TS, Olsen-P, and available K), and GRSP concentration. The contribution of GRSP-bound metals and its sequestration potential were calculated to assess the metal sequestration ability of GRSP.
Results and discussion
Mycorrhizal root colonization of
P. vittata
was significantly higher than that of
M. sinensis
and
C. rotundus
at three sites.
P. vittata
also exhibited significantly more GRSP accumulation than the other two plants in soil. The significant negative correlation between GRSP and the combined indicators of eight bioavailable (
r
= − 0.60,
p
< 0.001) or total (
r
= − 0.39,
p
< 0.01) metals’ concentration was found. Averaged across the polluted sites, in
P. vittata
soil, GRSP showed a higher contribution to sequestering most heavy metals (Cu, Cd, Pb, Zn, As, Sb, and Ni), compared with that in
M. sinensis
and
C. rotundus
soil, although the sequestration potential descended in the order of
C. rotundus
>
P. vittata
>
M. sinensis
.
Conclusions
AMF-
P. vittata
symbiosis presented higher contribution to sequestering most metals by GRSP in the contaminated sites when compared with the plants
M. sinensis
and
C. rotundus
. This study sheds light on the ecological function of GRSP sequestration of metals associated with mycorrhizal plants, and its contribution to reducing metal bioavailability in polluted sites.
As the largest light-harvesting complex in cyanobacteria, phycobilisomes (PBSs) show high efficiency and a high rate of energy transfer, owing to an elegant antenna-like assembly. To understand the ...structural influence on the dynamic process of the energy transfer in PBSs, two cyanobacterium species Thermosynechococcus vulcanus NIES 2134 (T. 2134) and Synechocystis sp. PCC 6803 (S. 6803) with different rod–core-linked assemblies were chosen for this study. The dynamic process of the energy transfer in both PBSs was investigated through time-resolved fluorescence spectroscopy (TRFS) with a time resolution of sub-picosecond. Via the fluorescence decay curves deconvolution, the pathways and related rates of the excitation energy transfer (EET) were determined. Three time components, i.e., 10, 80, and 1250 ps, were identified in the EET in the PBSs of T. 2134 and three, i.e., 9, 115, and 1680 ps, in the EET in the PBSs of S. 6803. In addition, a comparison of the dynamic process of the energy transfer between the two cyanobacteria revealed how the PBS assembly affects the energy transfer in PBSs. The findings will provide insight into future time-resolved crystallography.
PDF
