Extremophile organisms are known that can metabolize at temperatures down to - 25 °C (psychrophiles) and up to 122 °C (hyperthermophiles). Understanding viability under extreme conditions is relevant ...for human health, biotechnological applications, and our search for life elsewhere in the universe. Information about the stability and dynamics of proteins under environmental extremes is an important factor in this regard. Here we compare the dynamics of small Fe-S proteins - rubredoxins - from psychrophilic and hyperthermophilic microorganisms, using three different nuclear techniques as well as molecular dynamics calculations to quantify motion at the Fe site. The theory of 'corresponding states' posits that homologous proteins from different extremophiles have comparable flexibilities at the optimum growth temperatures of their respective organisms. Although 'corresponding states' would predict greater flexibility for rubredoxins that operate at low temperatures, we find that from 4 to 300 K, the dynamics of the Fe sites in these homologous proteins are essentially equivalent.
H2 is a CO2 free energy carrier that can be produced biologically through dark fermentation using specific bacteria. In general, biological production of H2 needs a carbon source and is more ...efficient at higher temperatures. Mature petroleum reservoirs have the required high temperatures for H2 production, and they contain a significant amount of organic matter in form of residual hydrocarbons. In this work, we evaluated whether indigenous microorganisms isolated from hydrocarbon reservoirs are able to biorefine hydrocarbons to H2. We observed that two Thermotoga strains, Pseudothermotoga hypogea DSM-11164 and Pseudothermotoga elfii DSM-9442, are able to convert hydrocarbons to H2. DSM 9442 produced 0.47 and 1.02 mmol H2 per liter of growth medium from 20 mL/L of n-hexadecane or a crude oil, respectively. DSM 11164 only produced H2 from n-hexadecane (0.94 mmol/L). Addition of 25 mg/L Tween 80, to reduce phase separation, together with 1 g/L glucose increased H2 production from hydrocarbons up to 12-fold. Via an energy analysis we show that bioconversion of crude oil into H2 can be more efficient than conversion of crude oil to gasoline. Therefore, we suggest dark fermentation as a promising alternative to biorefine crude oil and unlock the energy trapped in hydrocarbon reservoirs after abandonment.
Display omitted
•Thermotoga strains can produce H2 through dark fermentation of hydrocarbons.•Tween80 and glucose boost conversion of hydrocarbons to H2 up to 12-fold.•Biohydrogen production rate from hydrocarbons is only a quarter of that of glucose.•Bioconversion of hydrocarbons to H2 is more efficient than to gasoline.•Biorefinement is a sustainable solution for abandonment of mature oil reservoirs.
A novel hyperthermophilic archaeon of strain HS-3
, belonging to the family Sulfolobaceae, was isolated from an acidic terrestrial hot spring in Hakone Ohwaku-dani, Japan. Based on 16S rRNA gene ...sequence analysis, the closest phylogenetic relatives of strain HS-3
were, first, Sulfolobus solfataricus (96.4 %) and, second, Sulfolobus shibatae (96.2 %), indicating that the strain belongs to the genus Sulfolobus. However, the sequence similarity to the type species of the genus Sulfolobus (Sulfolobus acidocaldarius) was remarkably low (91.8 %). In order to determine whether strain HS-3
belongs to the genus Sulfolobus, its morphological, biochemical and physiological characteristics were examined in parallel with those of S. solfataricus and S. shibatae. Although there were some differences in chemolithotrophic growth between strain HS-3
, S. solfataricus and S. shibatae, their temperature, pH and facultatively anaerobic characteristics of growth, and their utilization of various sugars were almost identical. In contrast, the utilization of various sugars by S. acidocaldarius was quite different from that of HS-3
, S. solfataricus and S. shibatae. Phylogenetic evidence based on the 16S and the 23S rRNA gene sequences also clearly distinguished the monophyletic clade composed of strain HS-3
, S. solfataricus, and S. shibatae from S. acidocaldarius. Based on these results, we propose a new genus and species, Saccharolobus caldissimus gen. nov., sp. nov., for strain HS-3
, as well as two reclassifications, Saccharolobus solfataricus comb. nov. and Saccharolobus shibatae comb. nov. The type strain of Saccharolobus caldissimus is HS-3
(=JCM 32116
and InaCC Ar80
). The type species of the genus is Saccharolobus solfataricus.
Genetic manipulation is an essential tool to investigate complex microbiological phenomena. In this chapter we describe the techniques required to transform the model hyperthermophilic, anaerobic ...archaeon Thermococcus kodakarensis. T. kodakarensis can support two modes of genetic manipulation, dependent either on homologous recombination into the genome or through retention of autonomously replicating plasmids. The robust genetic system developed in T. kodakarensis offers a variety of selectable and counterselectable markers for complex, accurate and iterative genetic manipulations offering greater flexibility to probe gene function in vivo.
is a hyperthermophilic archaeon that harbors a complete set of genes for chitin degradation to fructose 6-phosphate. However, wild-type
KOD1 does not display growth on chitin. In this study, we ...developed a
strain that can grow on chitin via genetic and adaptive engineering. First, a chitinase overproduction strain (KC01) was constructed by replacing the chitinase gene promoter with a strong promoter from the cell surface glycoprotein gene, resulting in increased degradation of swollen chitin and accumulation of
-,
'-diacetylchitobiose in the medium. To enhance
-,
'-diacetylchitobiose assimilation in KC01, genes encoding diacetylchitobiose deacetylase, exo-β-d-glucosaminidase, and glucosamine-6-phosphate deaminase were also overexpressed to obtain strain KC04. To strengthen the glycolytic flux of KC04, the gene encoding Tgr (transcriptional repressor of glycolytic genes) was disrupted to obtain strain KC04Δt. In both KC04 and KC04Δt strains, degradation of swollen chitin was further enhanced. In the culture broth of these strains, the accumulation of glucosamine was observed. KC04Δt was repeatedly inoculated in a swollen-chitin-containing medium for 13 cultures. This adaptive engineering strategy resulted in the isolation of a strain (KC04ΔtM1) that showed almost complete degradation of 0.4% (wt/vol) swollen chitin after 90 h. The strain produced high levels of acetate and ammonium in the culture medium, and, moreover, molecular hydrogen was generated. This strongly suggests that strain KC04ΔtM1 has acquired the ability to convert chitin to fructose 6-phosphate via deacetylation and deamination and further convert fructose 6-phosphate to acetate via glycolysis coupled to hydrogen generation.
Chitin is a linear homopolymer of β-1,4-linked
-acetylglucosamine and is the second most abundant biomass next to cellulose. Compared to the wealth of research focused on the microbial degradation and conversion of cellulose, studies addressing microbial chitin utilization are still limited. In this study, using the hyperthermophilic archaeon
as a host, we have constructed a strain that displays chitin-dependent hydrogen generation. The apparent hydrogen yield per unit of sugar consumed was slightly higher with swollen chitin than with starch. As gene manipulation in
is relatively simple, the strain constructed in this study can also be used as a parent strain for the development and expansion of chitin-dependent biorefinery, in addition to its capacity to produce hydrogen.
Hydrogenotrophic methanogens are an intriguing group of microorganisms from the domain Archaea. Methanogens exhibit extraordinary ecological, biochemical, and physiological characteristics and ...possess a huge biotechnological potential. Yet, the only possibility to assess the methane (CH4) production potential of hydrogenotrophic methanogens is to apply gas chromatographic quantification of CH4. In order to be able to effectively screen pure cultures of hydrogenotrophic methanogens regarding their CH4 production potential we developed a novel method for indirect quantification of the volumetric CH4 production rate by measuring the volumetric water production rate. This method was established in serum bottles for cultivation of methanogens in closed batch cultivation mode. Water production was estimated by determining the difference in mass increase in a quasi-isobaric setting. This novel CH4 quantification method is an accurate and precise analytical technique, which can be used to rapidly screen pure cultures of methanogens regarding their volumetric CH4 evolution rate. It is a cost effective alternative determining CH4 production of methanogens over CH4 quantification by using gas chromatography, especially if applied as a high throughput quantification method. Eventually, the method can be universally applied for quantification of CH4 production from psychrophilic, thermophilic and hyperthermophilic hydrogenotrophic methanogens.
Sewage sludge treatment and disposal remains a challenging problem. Composting of sewage sludges is gaining increasing attention due to its cost-effectiveness, operation convenience, advantages in ...lifecycle management, and low greenhouse gas emissions. Disadvantages, such as long reaction time, significant land area occupation requirement, potential risks of residual heavy metals, and emerging contaminants, have restricted wider application. Here we review applications of hyperthermophiles in composting , focusing on the unique improvements provided by hyperthermophiles in composing temperatures, product safety, nitrogen preservation and humification. Inoculation of hyperthermophiles allows temperature of composting to reach over 80°C. Specific metabolic strategies are critical in hyperthermophiles-inoculated composting. High-temperature resistance in the metabolism of hyperthermophiles and their roles in temperature rising during composting is often overlooked. This review discusses both aspects, allowing for a deeper understanding of the functions and influences of hyperthermophiles in sludge composting. Additionally, this review highlights the policy challenges associated with the hyperthermophiles-inoculated sludge composing technique and provides potential directions for future research in this field.
Rapid treatment processing for agricultural waste is of the utmost importance with the boom in China's agriculture sector. Ultra-high temperature aerobic fermentation pre-treatment process assisted ...composting (HTC) is superior to traditional composting (CCT) with enhanced compost maturity and accelerated organic matter degradation. This research aimed to optimize and investigate the change in the chemical composition of ultra-high aerobic fermentation pre-treatment (UHT-AF) during agricultural waste composting and compare the effects of HTC and CCT on physio-chemical and biological parameters for compost quality assessment. Taguchi analysis based on physio-chemical parameters of pretreated-product provided experiment R5 (75 °C, 15 h, 40 g/kg) as optimal conditions. Comparative results revealed that HTC is superior to CCT with a shortened maturity period of 24 days. HTC showed a very rapid increase in high temperature (96.02 °C on the 3rd day) and a long-lasted thermophile stage (day 1–20 ≥ 60 °C). The C/N ratio reduced from 21.33 to 15.57, moisture content 60.5–35.5%, pH from 7.80 to 8.17, and compost showed GI ≥ 95%. The FTIR analysis of optimal pretreated-product confirmed that the UHF-AF technique could promote lignocellulose degradation and lignin degradation in subsequent composting, and SEM images provided clear morphological evidence of lignocellulose degradation. The study suggested UHT-AF pretreated (HTC) as a promising agricultural waste composting technique for rapid degradation of organic matter and enhanced quality compost production.
Display omitted
•Novel thermal pretreatment process for agricultural waste composting.•UHT-AF pretreatment composting is superior (HTC) to traditional composting (CCT).•Ultra-high temperature and a long-lasted thermophile stage during subsequent composting.•Total nitrogen retained in HTC and CCT compost was 91% and 80%, respectively.
High hydrostatic pressure (HHP) is a common factor in the deep sea and provides an ignorable parameter of consideration in all studies related to deep life. High-temperature environments in the deep ...sea, mainly including hydrothermal vents and deep sediments in the subseafloor, support enormous amounts of biomass, productivity, and diversity of life. Many microbes living there are usually (hyper)thermophilic piezophiles, which cope with the dual stresses of high temperature and HHP at the same time and playing significant roles in geochemical elemental cycling. Knowledge of the upper temperature limit of life under deep-sea HHP conditions can help us to estimate the boundary of the biosphere and explore its habitability on Earth and in extraterrestrial areas, but uncertainties remain. Here, we have summarized the current known knowledge of physiological correlations between high temperature and HHP, as well as the effects of HHP on cells at high temperature. These effects mainly comprise two aspects: biological integrity and metabolic feasibility. The former has been investigated in many studies on various microorganisms, from which we can draw a general conclusion that HHP helps cells maintain biological integrity under high temperature. For the latter, existing studies have provided clues suggesting that both high temperature and HHP challenge metabolic feasibility, but it is still difficult to draw conclusions on the additive effects on metabolism due to the lack of systematic analysis. Here, we also propose a series of questions for further investigation and called for more attention on metabolic responses to high temperature and HHP; this could provide a direct bridge between geochemistry and ecology, help us to understand the microbial functions in the deep biosphere and allow us to estimate the boundaries of life and habitats.
•We summarized the current knowledge of physiological correlations between high temperature and high hydrostatic pressure (HHP);•The effects of HHP on cells at high temperature mainly comprise two aspects: biological integrity and metabolic feasibility;•HHP generally helps cells maintaining biological integrity under high temperature;•Both high temperature and HHP challenge metabolic feasibility, but the additive effects need further systematic analysis;•We also proposed a series of questions for further investigation.
PDF
