Image_1_The Effect of Hydrostatic Pressure on Enrichments of Hydrocarbon Degrading Microbes From the Gulf of Mexico Following the Deepwater Horizon Oil Spill.PDF

<p>The Deepwater Horizon oil spill was one of the largest and deepest oil spills recorded. The wellhead was located at approximately 1500 m below the sea where low temperature and high pressure are key environmental characteristics. Using cells collected 4 months following the Deepwater Horizon oil spill at the Gulf of Mexico, we set up Macondo crude oil enrichments at wellhead temperature and different pressures to determine the effect of increasing depth/pressure to the in situ microbial community and their ability to degrade oil. We observed oil degradation under all pressure conditions tested [0.1, 15, and 30 megapascals (MPa)], although oil degradation profiles, cell numbers, and hydrocarbon degradation gene abundances indicated greatest activity at atmospheric pressure. Under all incubations the growth of psychrophilic bacteria was promoted. Bacteria closely related to Oleispira antarctica RB-8 dominated the communities at all pressures. At 30 MPa we observed a shift toward Photobacterium, a genus that includes piezophiles. Alphaproteobacterial members of the Sulfitobacter, previously associated with oil-degradation, were also highly abundant at 0.1 MPa. Our results suggest that pressure acts synergistically with low temperature to slow microbial growth and thus oil degradation in deep-sea environments.</p

MOESM6 of Water-splitting-based, sustainable and efficient H2 production in green algae as achieved by substrate limitation of the Calvin–Benson–Bassham cycle

Additional file 6: Figure S4. H2 production yields (a, c) and O2 concentrations in the headspaces of the serum bottles (b, d) at 15, 30 and 50 µg chl (a + b)/ml culture in the absence (a, b) and the presence (c, d) of an iron-salt-based O2 absorbent. Apart from changing the chl concentrations, the experimental conditions are identical to Fig. 4. The cultures were flushed with N2 for 10 min every 24 h after determining the gas concentrations in the headspaces of the sealed bottles. Mean values (± SEM) are each based on 5 to 6 biological replicates

MOESM1 of Water-splitting-based, sustainable and efficient H2 production in green algae as achieved by substrate limitation of the Calvin–Benson–Bassham cycle

Additional file 1: Figure S1. General scheme of the H2 production experiment induced by dark anaerobic incubation. Notes: (1) HS media was used in most experiments, except for Fig. 1, where TAP, TP, HSA, HS and TAP-S media were compared. (2) Before the start of dark anaerobic incubation, O2 absorbent was placed in the headspaces of the cultures (Figs. 4, 5, 6, Additional file 6: Fig. S4, Additional file 7: Fig. S5). (3) Chemicals were added after 3 h of illumination (Fig. 2) or at the beginning of illumination (Fig. 3). (4) Sampling of the cultures at various time intervals (Figs. 5, 6, Additional file 2: Fig. S2, Additional file 4: Fig. S3, Additional file 6: Fig. S4, Additional file 7: Fig. S5). (5) The cultures were regenerated following the 96-h H2 production using HS medium and CO2 bubbling; afterwards, a second round of H2 production was carried out (Fig. 7)

MOESM7 of Water-splitting-based, sustainable and efficient H2 production in green algae as achieved by substrate limitation of the Calvin–Benson–Bassham cycle

Additional file 7: Figure S5. Continuous H2 production (a) and O2 accumulation (b) at 50 µg chl (a + b)/ml culture in the absence and the presence of an iron-salt-based O2 absorbent. Apart from omitting the daily N2 flushing, the experimental conditions are identical to Fig. 4. Mean values (± SEM) are each based on 5–6 biological replicates

MOESM5 of Water-splitting-based, sustainable and efficient H2 production in green algae as achieved by substrate limitation of the Calvin–Benson–Bassham cycle

Additional file 5: Table S2. The effects of the separate and combined additions of glucose (Glc, 2 mM), glucose oxidase (GO, 0.2 mg/ml) and ascorbate (Asc, 1 mM) on the net H2 and O2 productions of Chlamydomonas cultures subjected to dark anaerobic incubation of 4 h in HS medium followed by continuous illumination of 320 µmol photons/m2/s, as determined in the headspaces of sealed cultures using gas chromatography. Mean values (± SEM in parentheses) are each based on 4 to 8 biological replicates

MOESM2 of Water-splitting-based, sustainable and efficient H2 production in green algae as achieved by substrate limitation of the Calvin–Benson–Bassham cycle

Additional file 2: Figure S2. Starch content of Chlamydomonas cultures subjected to dark anaerobic incubation followed by continuous illumination at 320 µmol photons/m2/s in acetate-free HS medium. Time 0 is the time point when the cultures were transferred to the light

MOESM3 of Water-splitting-based, sustainable and efficient H2 production in green algae as achieved by substrate limitation of the Calvin–Benson–Bassham cycle

Additional file 3: Table S1. The percentage of CO2 in the headspaces of sealed cultures of Chlamydomonas cultures subjected to dark anaerobic incubation of 4 h in HS medium followed by continuous illumination of 320 µmol photons/m2/s, as determined using gas chromatography. Mean values (± SEM in parentheses) are each based on 4–6 biological replicates. bld: below detection limit of 0.01%

MOESM4 of Water-splitting-based, sustainable and efficient H2 production in green algae as achieved by substrate limitation of the Calvin–Benson–Bassham cycle

Additional file 4: Figure S3. Fast chl a fluorescence (OJIP) transients of Chlamydomonas cultures subjected to dark anaerobic incubation followed by continuous illumination at 320 µmol photons/m2/s in acetate-free HS medium. Time 0 is the time point when the cultures were transferred to the light. For the fluorescence measurements, the cultures were measured immediately after taking them from the serum bottles, without any dark adaptation

Effect of Operational Parameters in the Continuous Anaerobic Fermentation of Cheese Whey on Titers, Yields, Productivities, and Microbial Community Structures

Volatile fatty acids (VFAs) were produced using cheese whey as feedstock. A mixed culture packed bed bioreactor was set up to digest anaerobically, under an acidogenic condition, a water solution of a cheese whey powder. Batch tests pointed out that the whole VFAs production process occurred via two sequential phases: (a) conversion of lactose into lactic acid and (b) conversion of lactic acid into a mixture of VFAs. Furthermore, the same tests showed that the ceramic material Vukopor S10 can be used as an effective support for cell immobilization in anaerobic fermentation processes. The effect of the hydraulic retention time (HRT) and organic loading rate (OLR) were then studied in a benchtop bioreactor operated continuously. By a HRT of 6 days, ORL of 4.2 g/L/d, and pH 5.8–6, 16 g·L^–1 of total VFAs were produced, with a yield higher than 75% (Cmol_VFAs·Cmol_lactose^–1). Characterization with Illumina-based sequencing suggested that high VFAs productivities were obtained when microbial community structures developed in the biofilm reactor were highly enriched in few genera