Single Organic Substrate Research Articles

Cyanobacterial production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) from carbon dioxide or a single organic substrate: improved polymer elongation with an extremely high 3-hydroxyvalerate mole proportion

The bioplastic poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) changes material properties upon altering mole ratio (mol%) of the two monomers: 3-hydroxybutyrate (HB) and 3-hydroxyvalerate (HV). Biotechnology for producing PHBV with a wide range of HV mol% using low amount of organic substrate is required. Here, 20 evolutionarily divergent cyanobacteria were examined for PHBV production. Under photoautotrophy with carbon dioxide (CO2) supply, one strain produced PHBV. But under heterotrophy using a medium containing only one type of organic substrate, 4, 15, and 13 strains were found to accumulate PHBV when supplied with acetate (C2H3O2), propionate (C3H5O2), and valerate (C5H9O2), respectively. Hence, these cyanobacterial PHBV productions required only CO2 or a single type of organic substrate. The obtained PHBV showed a broad range of HV mole ratios from 4 to 96 mol%. The cells producing PHBV with high HV mole ratios (31–96 mol%) exhibited low cellular acetyl-CoA levels. The PHBV with a 96.2 mol% HV and 3.8 mol% HB from Nostoc microscopicum elongated at 98 ± 15% (length/length), a 19.6-fold higher elongation than that of commercial poly-3-hydroxybutyrate containing 100 mol% HB. The results demonstrated the economical utility of cyanobacterial conversion of CO2 and a single organic substrate to synthesize PHBV with improved elongation quality.

The Effect of C/N Ratio and Type of Microbes Sludge to Biogas Production: Combination of Tapioca Industrial Wastewater and Tofu Industrial Wastewater

Biogas will be produced from a single organic substrate and controlled the ratio of carbon nitrogen by added inorganic nitrogen substances. The study has been tried to combine substrates from industrial tapioca industrial wastewater with tofu industrial wastewater. The experiments were carried out in batch anaerobic digesters with a C/N ratio range of 20 - 30 and variation of microbial sludge from cow rumen, anaerobic sludge of tofu wastewater treatment plant (WWTP) and anaerobic sludge of tapioca WWTP. The ratio of C/N in the range of 20-30 didn’t significant effect on the volume of biogas production. The microbial from cow rumen gives the best biogas production performance. Biogas yield is 2,199 liter per kg COD.

Diversidad cultural y estilos cognitivos

Speech and thought have a single organic substrate: the cerebral hemispheres, which are responsible for processing the information received through the senses and give it meaning based on the culture and the language we use to put it into words. But this information is not processed in the same way in all cultures and with different languages. What impact can have an educational model that aims to be universal in children with different cognitive models? Is that an education Westernized and Universalist is suitable for all type of culture and of language?

Two-stage (photoautotrophy and heterotrophy) cultivation enables efficient production of bioplastic poly-3-hydroxybutyrate in auto-sedimenting cyanobacterium

Sustainable production of bioplastics by heterotrophic microbes has been restricted by the limited resources of organic substrates and the energy required for biomass harvest. Here, the easy-to-harvest cyanobacterium (Chlorogloea fritschii TISTR 8527), from which the biomass instantaneously settled to the bottom of liquid culture, was utilized to produce poly-3-hydroxybutyrate (PHB) using a two-stage cultivation strategy. The cells were first pre-grown under normal photoautotrophy to increase their biomass and then recultivated under a heterotrophic condition with a single organic substrate to produce the product. Through optimization of this two-stage cultivation, the mass conversion efficiency of acetate substrate to PHB was obtained at 51 ± 7% (w/w), the comparable level to the theoretical biochemical conversion efficiency of acetate to PHB. This two-stage cultivation that efficiently converted the substrate to the product, concurrent with a reduced culture biomass, may be applicable for the production of other biopolymers by cyanobacteria.

Titania produced from Ti-salt flocculated sludge: photocatalytic activity under solar light.

In this study, titania photocatalyst was produced from the wastewater sludge of Ti-salt flocculation. The high photocatalytic activity of titania reported was evaluated based on a single organic substrate. However, the photocatalytic activity is a substrate-specific; one photocatalyst showed different photocatalytic degradation rates for different substrates. Thus, to investigate the substrate-specific photocatalytic activity of titania, various substrates of humic acid (HA), dichloroacetic acid (DCA), rhodamine B (RhB), metsulfuron methyl (M&M) and phenol were used under simulated solar light irradiation. Results showed titania had a high activity rate for RhB, moderate activity for HA and DCA and low activity for M&M and phenol indicating substrate-specific activities. When compared with Degussa-P25, titania showed higher activity for M&M, while the opposite was observed for HA and phenol. The specific-substrate behaviour of titania could depend on specific physicochemical and electronic interactions between titania, substrates, and their intermediates compounds formed.

Effect of dual substrate environment on the formation of intracellular storage biopolymers

We investigated the effect of a starch/acetate mixture on the formation of intracellular storage biopolymers compared with system behaviour where these compounds served as a single organic substrate. Three laboratory-scale sequencing batch reactors (SBRs) were operated at steady state with a sludge age of 8 days, one fed with acetate, another with starch and the third with a starch/acetate mixture. The SBR operation involved six cycles per day and continuous feeding during each cycle. Both acetate and starch generated storage biopolymers under continuous feeding. A poly-hydroxybutyrate (PHB) or glycogen pool was formed depending on the selected single substrate. In addition, around 18% of the acetate fed within each cycle was converted to PHB, while the remaining 82% was directly utilized for microbial growth. A higher glycogen formation of 44% was observed for starch. Substrate storage as PHB and glycogen continued with the feeding of the acetate/starch mixture. This observation, supported by microbiological analyses, indicated that the acclimated biomass in the corresponding SBR system sustained microbial fractions capable of performing metabolic functions associated with the formation of the two storage biopolymers. PHB accumulation was reduced as acetate could be more readily used for direct microbial growth in the presence of starch.

Links between bacterial production, amino-acid utilization and community composition in productive lakes

Influence of distribution and abundance of bacterial taxa on ecosystem function are poorly understood for natural microbial communities. We related 16S rRNA-based terminal restriction fragment length polymorphism to bacterial production and arginine uptake kinetics to test if functional features of bacterioplankton in four lakes could be predicted from community composition. Maximum arginine uptake rate (arginine V(max)) ranged from 10% to 100% of bacterial production. Owing to high growth efficiencies on arginine (63-77%), the bacterial community could potentially saturate its carbon demand using this single organic substrate, for example, during sudden surges of free amino acids. However, due to low in situ concentrations of arginine in these lakes (<0.9 microg l(-1)), actual uptake rates at ambient concentrations rarely exceeded 10% of V(max). Bacterial production and arginine V(max) could be predicted from a subset of bacterial ribotypes, tentatively affiliated with several bacterial divisions (Cyanobacteria, Actinobacteria, Bacteroidetes and Proteobacteria). Multivariate statistical analysis indicates that there were both highly important and less important ribotypes for the prediction of bacterial production and arginine V(max). These populations were either negatively or positively related to the respective functional feature, indicating contrasting ecological roles. Our study provides a statistically robust demonstration that, apart from environmental conditions, patterns in bacterial community composition can also be used to predict lake ecosystem function.

Diversity of bacteria and Archaea in sulphate-reducing enrichment cultures inoculated from serial dilution of Zostera noltii rhizosphere samples.

We have analysed the diversity of culturable sulphate-reducing bacteria (SRB) in Zostera noltii colonized sediments from Bassin d'Arcachon (France). Four organic substrates have been tested as well as the combination of H2 and CO2 to select for lithotrophic SRB. All energy sources were supplied in parallel cultures that were amended with yeast extract plus NH4+ and prepared without a source of combined nitrogen, the latter to select for diazotrophic SRB. The 10 different enrichment media were inoculated from serial dilution of rhizosphere samples. The highest dilution cultures yielding positive growth (i.e. 10-7) were studied by molecular techniques (16S rDNA clone libraries, RISA and ARDRA). Lactate as a single organic substrate in combination with a source of combined nitrogen resulted in selection of members of the Desulfovibrionaceae. Surprisingly, when lactate was added without a source of combined nitrogen, Desulfobacteriaceae were selected. A strong influence of the presence or absence of combined nitrogen was also observed for the substrates sucrose and fructose. Whereas the liquid culture growing on sucrose and NH4+ systematically yielded 16S rDNA clones related to an environmental unidentified green sulphur bacterium (OPS185), on plates we were able to isolate a SRB related to Desulfovibrio dechloracetivorans, which likely represents a non-described species. Under diazotrophic conditions, sucrose selected for SRB clones related to the cluster formed by Desulfovibrio zosterae, Desulfovibrio salexigens and Desulfovibrio bastinii. The corresponding isolate obtained on plates showed only low sequence similarity with this closest neighbour (93.8%), and we suggest that it also represents a non-described species. Surprisingly, a 16S rDNA sequence corresponding to an archaeon, i.e. a non-extremophile Crenoarchaeota, was retrieved from several of the SRB enrichment cultures even after subsequent transfers.

Comparison of approaches for simulating reactive solute transport involving organic degradation reactions by multiple terminal electron acceptors

Reactive solute transport models are useful tools for analyzing complex geochemical behavior resulting from biodegradation of organic compounds by multiple terminal electron acceptors (TEAPs). The usual approach of simulating the reactions of multiple TEAPs by an irreversible Monod rate law was compared with simulations that assumed a partial local equilibrium or kinetically controlled reactions subject to the requirement that the Gibbs free energy of reaction (Δ G) was either less than zero or less than a threshold value. Simulations were performed using a single organic substrate and O 2, FeOOH, SO 4 −2 and CO 2 as the terminal electron acceptors. It was assumed that the organic substrate was slowly and completely fermented to CO 2 and H 2 and the H 2 was oxidized by the TEAPs. Simulations using the Monod approach showed that this irreversible rate law forced the reduction of both FeOOH and CO 2 to proceed even when Δ G was positive. This resulted in an over prediction in amount of FeOOH reduced to Fe(II) in parts of the domain and it resulted in large errors in pH. Simulations using mass action kinetics agreed with equilibrium simulations for the case of large rate constants. The extent of reductive dissolution of FeOOH was strongly dependent on the thermodynamic stability of the FeOOH phase. Transport simulations performed assuming that the reactions of the TEAPs stopped when Δ G exceeded a threshold value showed that only simulated H 2 concentrations were affected if the threshold value was the same for each TEAP. Simulated H 2 concentrations were controlled by the fastest reaction of the TEAP, but it was common for reactions to occur concomitantly rather than sequentially.

Production of unusual bacterial polyesters by Pseudomonas oleovorans through cometabolism

Pseudomonas oleovorans is an adaptable, aerobic bacterium that can produce a wide range of storage polyesters (poly-β-hydroxyalkanoates, PHAs). With few exceptions, the PHAs obtained when this bacterium is grown with single organic substrates capable of polymer production are generally copolymers. With two different polymer-producing substrates the copolymers formed contain units derived from each substrate often in direct proportion to the amounts in the medium. With such substrates or with non-producing substrates, or with non-growth substrates, the ability of P. oleovorans to utilize different types of individual organic compounds can be classified into three different categories, as follows: group A — the organic compound can support both growth and polymer production; or group B — the organic compound can support growth but not polymer production; or group C — the organic compounds cannot support growth. For organic compounds in groups B and C, new and unusual copolymers containing units derived from these substrates can often be obtained if that compound is cofed with a good polymer-producing substrate for P. oleovorans, such as either octanoic acid or nonanoic acid. The PHAs obtained by this type of cometabolism from a variety of such substrates are described.

Production of unusual bacterial polyesters byPseudomonas oleovoransthrough cometabolism

Abstract Pseudomonas oleovorans is an adaptable, aerobic bacterium that can produce a wide range of storage polyesters (poly-β-hydroxyalkanoates, PHAs). With few exceptions, the PHAs obtained when this bacterium is grown with single organic substrates capable of polymer production are generally copolymers. With two different polymer-producing substrates the copolymers formed contain units derived from each substrate often in direct proportion to the amounts in the medium. With such substrates or with non-producing substrates, or with non-growth substrates, the ability of P. oleovorans to utilize different types of individual organic compounds can be classified into three different categories, as follows: group A — the organic compound can support both growth and polymer production; or group B — the organic compound can support growth but not polymer production; or group C — the organic compounds cannot support growth. For organic compounds in groups B and C, new and unusual copolymers containing units derived from these substrates can often be obtained if that compound is cofed with a good polymer-producing substrate for P. oleovorans , such as either octanoic acid or nonanoic acid. The PHAs obtained by this type of cometabolism from a variety of such substrates are described.

Dual-frequency chemical oscillators with acetylphenols as substrates

New dual-frequency chemical oscillators are reported. The system is of Belousov-Zhabotinskii type with a single organic substrate (o-acetylphenol, m-acetylphenol, or p-acetylphenol) and metal catalyst (Ce 4+ , Fe(phen) 3 2+ , or Ru(bpy) 3 2+ ) in a batch reactor. The system first shows a high-frequency oscillation and then bifurcates into a stable, nonoscillating state. After a break of a few to a few tens of minutes, it bifurcates again to an oscillatory regime with lower frequency

Dynamic Changes in Populations of the Activated Sludge Community: Effects of Dissolved Oxygen Variations

A simple dynamic mathematical model was developed to describe a microbial system composed of two populations: filamentous and floc-forming bacteria. Growth rates of both microorganisms depend on the concentration of a single organic substrate and on the dissolved oxygen (DO) concentration. Biokinetic parameters were estimated from the experimental data reported in the literature. Using these parameters population changes were examined under variable DO concentrations. The comparison of the numerical simulations and experimental data indicated a possibility of controlling population composition within a desired range through periodic changes in DO concentration. The existence of a single common trajectory on phase plane guarantees the stability of the designed cycle.

Hydrogenase and ribulose diphosphate carboxylase during autotrophic, heterotrophic, and mixotrophic growth of scotochromogenic mycobacteria.

Two key autotrophic enzyme systems, hydrogenase and ribulose diphosphate carboxylase, were examined in Mycobacterium gordonae and two other chemolithotrophic, scotochromogenic mycobacteria under different cultural conditions. In all three organisms both enzymes were inducible and were produced in significant levels only in the presence of the specific substrate, hydrogen or carbon dioxide. M. gordonae exhibited increased growth rates and yields, indicating mixotrophic growth, in the presence of a number of single organic substrates, including acetate, pyruvate, glucose, fructose, and glycerol. In contrast to other aerobic hydrogen autotrophs, the presence of either acetate or pyruvate did not repress ribulose diphosphate carboxylase, and mixotrophic growth was rapid with these substrates. In the absence of carbon dioxide, growth in glycerol medium under an atmosphere of hydrogen and oxygen was severely inhibited, even with cells preadapted to heterotrophic growth on glycerol. Cyclic adenosine monophosphate was not effective in inducing hydrogenase or carboxylase in heterotrophic, mixotrophic, or hydrogen-inhibited cultures.

Thiobacillus perometabolis nov. sp., a non-autotrophic thiobacillus.

A new chemolithotrophic bacterium unable to grow autotrophically is described. Its growth occurs with yeast extract or casein hydrolysate and is greatly enhaced by the addition of thiosulfate or a variety of individual organic compounds. Growth also occurs in a mineral salts medium to which both thiosulfate and an appropriate single organic substrate are added but not with either supplement alone. Elemental sulfur, thiosulfate and tetrathionate are oxidized to sulfate. The taxonomic position of the organism is briefly discussed and the name Thiobacillus perometabolis is proposed.