Wide Range Of Sugars Research Articles

Biotechnological potential of psychrotolerant methylobacteria isolated from biotopes of Antarctic oases.

Ten strains of psychrotolerant methylotrophic bacteria were isolated from the samples collected in Larsemann and Bunger Hills (Antarctica). Most of the isolates are assigned to the genus Pseudomonas, representatives of the genera Janthinobacterium, Massilia, Methylotenera and Flavobacterium were also found. Majority of isolates were able to grow on a wide range of sugars, methylamines and other substrates. Optimal growth temperatures for the isolated strains varied from 6°C to 28°C. The optimal concentration of NaCl was 0.5-2.0%. The optimal pH values of the medium were 6-7. It was found that three strains synthesized indole-3-acetic acid on a medium with L-tryptophan reaching 11-12μg/ml. The values of intracellular carbohydrates in several strains exceeded 50μg/ml. Presence of calcium-dependent and lanthanum-dependent methanol dehydrogenase have been shown for some isolates. Strains xBan7, xBan20, xBan37, xBan49, xPrg27, xPrg48, xPrg51 showed the presence of free amino acids. Bioprospection of Earth cryosphere for such microorganisms has a potential in biotechnology.

Resveratrol production from several types of saccharide sources by a recombinant Scheffersomyces stipitis strain

Resveratrol is a plant-derived aromatic compound with a wide range of beneficial properties including antioxidant and anti-aging effects. The resveratrol currently available on the market is predominantly extracted from certain plants such as grape and the Japanese knotweed Polygonum cuspidatum. Due to the unstable harvest of these plants and the low resveratrol purity obtained, it is necessary to develop a stable production process of high-purity resveratrol from inexpensive feedstocks. Here, we attempted to produce resveratrol from a wide range of sugars as carbon sources by a using the genetically-engineered yeast Scheffersomyces stipitis (formerly known as Pichia stipitis), which possesses a broad sugar utilization capacity. First, we constructed the resveratrol producing strain by introducing genes coding the essential enzymes for resveratrol biosynthesis [tyrosine ammonia-lyase 1 derived from Herpetosiphon aurantiacus (HaTAL1), 4-coumarate: CoA ligase 2 derived from Arabidopsis thaliana (At4CL2), and stilbene synthase 1 derived from Vitis vinifera (VvVST1)]. Subsequently, a feedback-insensitive allele of chorismate mutase was overexpressed in the constructed strain to improve resveratrol production. The constructed strain successfully produced resveratrol from a broad range of biomass-derived sugars [glucose, fructose, xylose, N-acetyl glucosamine (GlcNAc), galactose, cellobiose, maltose, and sucrose] in shake flask cultivation. Significant resveratrol titers were detected in cellobiose and sucrose fermentation (529.8 and 668.6 mg/L after 120 h fermentation, respectively), twice above the amount obtained with glucose (237.6 mg/L). Metabolomic analysis revealed an altered profile of the metabolites involved in the glycolysis and shikimate pathways, and also of cofactors and metabolites of energy metabolisms, depending on the substrate used. The levels of resveratrol precursors such as L-tyrosine increased in cellobiose and sucrose-grown cells. The results indicate that S. stipitis is an attractive microbial platform for resveratrol production from broad types of biomass-derived sugars and the selection of suitable substrates is crucial for improving resveratrol productivity of this yeast.

Characterization and adaptation of Caldicellulosiruptor strains to higher sugar concentrations, targeting enhanced hydrogen production from lignocellulosic hydrolysates

BackgroundThe members of the genus Caldicellulosiruptor have the potential for future integration into a biorefinery system due to their capacity to generate hydrogen close to the theoretical limit of 4 mol H2/mol hexose, use a wide range of sugars and can grow on numerous lignocellulose hydrolysates. However, members of this genus are unable to survive in high sugar concentrations, limiting their ability to grow on more concentrated hydrolysates, thus impeding their industrial applicability. In this study five members of this genus, C.owensensis, C. kronotskyensis, C.bescii, C.acetigenus and C.kristjanssonii, were developed to tolerate higher sugar concentrations through an adaptive laboratory evolution (ALE) process. The developed mixed population C.owensensis CO80 was further studied and accompanied by the development of a kinetic model based on Monod kinetics to quantitatively compare it with the parental strain.ResultsMixed populations of Caldicellulosiruptor tolerant to higher glucose concentrations were obtained with C.owensensis adapted to grow up to 80 g/L glucose; other strains in particular C. kristjanssonii demonstrated a greater restriction to adaptation. The C.owensensis CO80 mixed population was further studied and demonstrated the ability to grow in glucose concentrations up to 80 g/L glucose, but with reduced volumetric hydrogen productivities (Q_{{{text{H}}_{2} }}) and incomplete sugar conversion at elevated glucose concentrations. In addition, the carbon yield decreased with elevated concentrations of glucose. The ability of the mixed population C.owensensis CO80 to grow in high glucose concentrations was further described with a kinetic growth model, which revealed that the critical sugar concentration of the cells increased fourfold when cultivated at higher concentrations. When co-cultured with the adapted C.saccharolyticus G5 mixed culture at a hydraulic retention time (HRT) of 20 h, C.owensensis constituted only 0.09–1.58% of the population in suspension.ConclusionsThe adaptation of members of the Caldicellulosiruptor genus to higher sugar concentrations established that the ability to develop improved strains via ALE is species dependent, with C.owensensis adapted to grow on 80 g/L, whereas C.kristjanssonii could only be adapted to 30 g/L glucose. Although C.owensensis CO80 was adapted to a higher sugar concentration, this mixed population demonstrated reduced Q_{{{text{H}}_{2} }} with elevated glucose concentrations. This would indicate that while ALE permits adaptation to elevated sugar concentrations, this approach does not result in improved fermentation performances at these higher sugar concentrations. Moreover, the observation that planktonic mixed culture of CO80 was outcompeted by an adapted C.saccharolyticus, when co-cultivated in continuous mode, indicates that the robustness of CO80 mixed culture should be improved for industrial application.

Hydrolysis of lignocellulose by anaerobic fungi produces free sugars and organic acids for two-stage fine chemical production with Kluyveromyces marxianus.

Development of the bioeconomy is driven by our ability to access the energy-rich carbon trapped in recalcitrant plant materials. Current strategies to release this carbon rely on expensive enzyme cocktails and physicochemical pretreatment, producing inhibitory compounds that hinder subsequent microbial bioproduction. Anaerobic fungi are an appealing solution as they hydrolyze crude, untreated biomass at ambient conditions into sugars that can be converted into value-added products by partner organisms. However, some carbon is lost to anaerobic fungal fermentation products. To improve efficiency and recapture this lost carbon, we built a two-stage bioprocessing system pairing the anaerobic fungus Piromyces indianae with the yeast Kluyveromyces marxianus, which grows on a wide range of sugars and fermentation products. In doing so we produce fine and commodity chemicals directly from untreated lignocellulose. P. indianae efficiently hydrolyzed substrates such as corn stover and poplar to generate sugars, fermentation acids, and ethanol, which K. marxianus consumed while producing 2.4g/L ethyl acetate. An engineered strain of K. marxianus was also able to produce 550 mg/L 2-phenylethanol and 150 mg/L isoamyl alcohol from P. indianae hydrolyzed lignocellulosic biomass. Despite the use of crude untreated plant material, production yields were comparable to optimized rich yeast media due to the use of all available carbon including organic acids, which formed up to 97% of free carbon in the fungal hydrolysate. This work demonstrates that anaerobic fungal pretreatment of lignocellulose can sustain the production of fine chemicals at high efficiency by partnering organisms with broad substrate versatility.

Surface Sulfate Ion on CdS Catalyst Enhances Syngas Generation from Biopolyols.

Photocatalytic biomass conversion represents an ideal way of generating syngas because of the sustainable use of biomass carbon and solar energy. However, the lack of efficient electron-proton transfer limits its efficiency. We here report an unprecedented method to simultaneously increase both the electron and proton transfer by creating surface sulfate ions on the CdS catalyst ([SO4]/CdS). Surface sulfate ion [SO4] is bifunctional, serving as the proton acceptor to promote proton transfer, and increasing the oxidation potential of the valence band to enhance electron transfer. [SO4]/CdS produces a syngas mixture from glycerol without CO2. Compared with pristine CdS, [SO4]/CdS exhibits 9-fold higher CO generation rate (0.31 mmol g-1 h-1) and 4-fold higher H2 generation (0.05 mmol g-1 h-1). A wide range of sugars, such as glucose, fructose, maltose, sucrose, xylose, lactose, insulin, and starch, were facilely converted into syngas. This study reports the pivotal effect of surface sulfate ion on electron-proton transfer in photocatalysis and provides a facile method for increasing photocatalytic efficiency.

Production of galactitol from galactose by the oleaginous yeast Rhodosporidium toruloides IFO0880

BackgroundSugar alcohols are commonly used as low-calorie sweeteners and can serve as potential building blocks for bio-based chemicals. Previous work has shown that the oleaginous yeast Rhodosporidium toruloides IFO0880 can natively produce arabitol from xylose at relatively high titers, suggesting that it may be a useful host for sugar alcohol production. In this work, we explored whether R. toruloides can produce additional sugar alcohols.ResultsRhodosporidium toruloides is able to produce galactitol from galactose. During growth in nitrogen-rich medium, R. toruloides produced 3.2 ± 0.6 g/L, and 8.4 ± 0.8 g/L galactitol from 20 to 40 g/L galactose, respectively. In addition, R. toruloides was able to produce galactitol from galactose at reduced titers during growth in nitrogen-poor medium, which also induces lipid production. These results suggest that R. toruloides can potentially be used for the co-production of lipids and galactitol from galactose. We further characterized the mechanism for galactitol production, including identifying and biochemically characterizing the critical aldose reductase. Intracellular metabolite analysis was also performed to further understand galactose metabolism.ConclusionsRhodosporidium toruloides has traditionally been used for the production of lipids and lipid-based chemicals. Our work demonstrates that R. toruloides can also produce galactitol, which can be used to produce polymers with applications in medicine and as a precursor for anti-cancer drugs. Collectively, our results further establish that R. toruloides can produce multiple value-added chemicals from a wide range of sugars.

Antibiofouling potential of quercetin compound from marine-derived actinobacterium, Streptomyces fradiae PE7and its characterization.

An attempt has been made to isolate, purify and characterize antifouling compound from Streptomyces fradiae PE7 isolated from Vellar estuarine sediment, Parangipettai, South India. The microbial identification was done at species level based on its phenotypic, cell wall and molecular characteristics. Strain PE7 produced high quantity of antifouling compounds in agar surface fermentation when compared to submerged fermentation. In fermentation optimization, wide range of sugars, amino acids, minerals, pH, temperature and NaCl concentration was found to influence the antifouling compound production from the strain PE7. Antifouling compound PE7-C was purified from the crude extract by preparative TLC, and its activity against biofouling bacteria was confirmed by bioautography. Based on the physico-chemical characteristics, the chemical structure of the antifouling compound PE7-C was identified as quercetin (C15H10O7), a flavonoid class of compound with the molecular weight 302.23g/mol. The purified quercetin was active against 18 biofouling bacteria with MIC range between 1.6 and 25μg/ml, algal spore germination and mollusc foot adherence found at 100μg/ml and 306 ± 19.6μgml(-1) respectively. The present study, for the first time, reported quercetin from marine-derived Streptomyces sp. PE7 with antifouling activity. This also leads to the repurposing of quercetin for the development of antifouling agent.

Production of dissolvable microneedles using an atomised spray process: Effect of microneedle composition on skin penetration

Dissolvable microneedles offer an attractive delivery system for transdermal drug and vaccine delivery. They are most commonly formed by filling a microneedle mold with liquid formulation using vacuum or centrifugation to overcome the constraints of surface tension and solution viscosity. Here, we demonstrate a novel microneedle fabrication method employing an atomised spray technique that minimises the effects of the liquid surface tension and viscosity when filling molds. This spray method was successfully used to fabricate dissolvable microneedles (DMN) from a wide range of sugars (trehalose, fructose and raffinose) and polymeric materials (polyvinyl alcohol, polyvinylpyrrolidone, carboxymethylcellulose, hydroxypropylmethylcellulose and sodium alginate). Fabrication by spraying produced microneedles with amorphous content using single sugar compositions. These microneedles displayed sharp tips and had complete fidelity to the master silicon template. Using a method to quantify the consistency of DMN penetration into different skin layers, we demonstrate that the material of construction significantly influenced the extent of skin penetration. We demonstrate that this spraying method can be adapted to produce novel laminate-layered as well as horizontally-layered DMN arrays. To our knowledge, this is the first report documenting the use of an atomising spray, at ambient, mild processing conditions, to create dissolvable microneedle arrays that can possess novel, laminate layering.

Exploring the Potential of C. Pasteurianum to Produce Biofuels from Waste Products

Biofuels which can be produced by microorganisms from agricultural waste products will provide a renewable and non controversial source of energy for the future. The saccharolytic Clostridium sp. can ferment a wide range of sugars to produce organic acids and solvents. They are also anaerobic and in some cases thermophilic which is advantageous for large-scale industrial processes. C.pasteurianum shows potentially high solvent and hydrogen gas production capacity. The fermentation end products of C.pasteurianum, when grown in media of high sugar content, included significant quantities of acetone, butanol and ethanol, acetate, butyrate, CO2 and H2. The aim of this research was to investigate maltose uptake and metabolism in Clostridium pasteurianum NCIB 9486, to increase understanding of its starch utilisation. The organism was grown in different substrates and assayed for induction of glucosidase activities. Results confirmed that enzyme synthesis is induced by substrates.MaltaseandpNPGasewere found largely in soluble form (89.5% and 86.6% respectively) proving that maltase is produced intracellularly and hydrolysis of maltose takes place in the cytpoplasm. Fractionationof the soluble extract ofmaltose growncells yielded two maltase enzymes, maltase I (120-150 KDa) and maltase II (60 KDa). Further characterisation of maltase II showed high substrate specificity for maltose and its analogues, and sucrose. Maltase II exhibited similar rates of hydrolysis of maltose andmaltotriose: values for Km of 0.8 and 0.7 mmol l-1;Vmax of 3.3 and 4.2 nmol min-1, respectively. There is indication of specific activity of maltase II in cleaving the -1,4 (maltose) and -1,6-(isomaltose) linkages, but not -linkages (cellobiose). PEP-dependent phosphorylation of maltose was demonstrated suggesting the presence of a PEP-dependent PTS for maltose transport. This species has potential for use in biofuel production and a better understanding of its carbohydrate metabolism will facilitate its exploitation.

Massilia brevitalea sp. nov., a novel betaproteobacterium isolated from lysimeter soil

A Gram-negative, strictly aerobic bacterium, designated strain byr23-80T, was isolated from lysimeter soil by using a high-throughput cultivation technique. Cells of strain byr23-80T were found to be short rods that multiplied by binary fission and were motile by means of a single polar flagellum. Occasionally, two to three polar or lateral flagella were observed. The optimum growth temperature was 15 degrees C and the pH optimum was 7.0-7.5. The predominant cellular fatty acids were C16 : 1omega7c (54.7 %) and C16 : 0 (21.4 %). In addition, the diagnostic fatty acids C10 : 0 3-OH and C12 : 0 2-OH were detected. Q-8 was the predominant respiratory quinone. The isolate was physiologically very versatile, using a wide range of sugars, organic acids and amino acids as single carbon and energy sources for growth. The G+C content of the genomic DNA was 65.3 mol%. Phylogenetic analyses supported the assignment of strain byr23-80T to the genus Massilia within the family Oxalobacteraceae of the class Betaproteobacteria. Within the genus, strain byr23-80T was most closely related to Massilia aurea DSM 18055T, with a 16S rRNA gene sequence similarity of 98.3 %. However, DNA-DNA hybridization revealed a pairwise similarity for the genomic DNA of only 20.1 % between strain byr23-80T and strain DSM 18055T. The novel isolate could be distinguished from the existing species Massilia timonae, Massilia dura, Massilia albidiflava, Massilia plicata, Massilia lutea and M. aurea by its significantly lower temperature optimum for growth and by the absence of gelatinase, alpha-galactosidase and beta-galactosidase activities. On the basis of these characteristics, strain byr23-80T constitutes a novel species of the genus Massilia, for which the name Massilia brevitalea sp. nov. is proposed. The type strain is byr23-80T (=DSM 18925T=ATCC BAA-1465T).

Investigation of the diversity of homoacetogenic bacteria in mesophilic and thermophilic anaerobic sludges using the formyltetrahydrofolate synthetase gene

Homoacetogenic bacteria are strict anaerobes capable of autotrophic growth on H(2)/CO(2) or CO, and of heterotrophic growth on a wide range of sugars, alcohols, methoxylated aromatic compounds and one carbon compounds, yielding acetate as their sole metabolic end-product. Batch activity tests on anaerobic granular sludge, using H(2)/CO(2) as a substrate and 2-bromoethanesulfonate (BES) as a specific methanogenic inhibitor revealed that H(2)/CO(2) conversion and concomitant acetate production commenced only after a lag period of 60-100 h. This finding suggests that the homoacetogenic population of digester sludge could be maintained by heterotrophic growth on sugars or other organic compounds, rather than by autotrophic growth on H(2)/CO(2). In the present study, two upflow anaerobic sludge bed (UASB) reactors were operated at 37 degrees C and 55 degrees C for two distinct trial periods, each characterised by the application of influents designed to enrich for homoacetogenic bacteria. Specific primers designed for the amplification of the functional gene encoding formyltetrahydrofolate synthetase (FTHFS), a key enzyme in the acetyl-CoA pathway of acetogenesis, were used as a specific probe for acetogenic bacteria. The diversity of acetogens in the granular sludge cultivated in each reactor was revealed by application of FTHFS targeted PCR. Results show that biomass acetogenic composition was dependent upon the operational temperature of the reactor and the substrate supplied as influent.

Physiological, Ecological, and Phylogenetic Characterization of Stappia , a Marine CO-Oxidizing Bacterial Genus

Bacteria play a major role in marine CO cycling, yet very little is known about the microbes involved. Thirteen CO-oxidizing Stappia isolates obtained from existing cultures, macroalgae, or surf samples representing geographically and ecologically diverse habitats were characterized using biochemical, physiological, and phylogenetic approaches. All isolates were aerobic chemoorganotrophs that oxidized CO at elevated (1,000 ppm) and ambient-to-subambient concentrations (<0.3 ppm). All contained the form I (OMP) coxL gene for aerobic CO dehydrogenase and also the form II (BMS) putative coxL gene. In addition, some strains possessed cbbL, the large subunit gene for ribulose-1,5-bisphosphate carboxylase/oxygenase, suggesting the possibility of lithotrophic or mixotrophic metabolism. All isolates used a wide range of sugars, organic acids, amino acids, and aromatics for growth and grew at salinities from 5 to 45 ppt. All but one isolate denitrified or respired nitrate. Phylogenetic analyses based on 16S rRNA gene sequences indicated that several isolates could not be distinguished from Stappia aggregata and contributed to a widely distributed species complex. Four isolates (of strains GA15, HI, MIO, and M4) were phylogenetically distinct from validly described Stappia species and closely related genera (e.g., Ahrensia, Pannonibacter, Pseudovibrio, and Roseibium). Substrate utilization profiles, enzymatic activity, and membrane lipid composition further distinguished these isolates and supported their designations as new Stappia species. The observed metabolic versatility of Stappia likely accounts for its cosmopolitan distribution and its ability to contribute to CO cycling as well as other important biogeochemical cycles.

The status and characterization of Enteroramus dimorphus: a xylose-fermenting yeast attached to the gut of beetles

Enteroramus dimorphus from the gut of the passalid beetle Odontotaenius disjunctus was described originally as a yeast-like fungus of unknown taxonomic affiliation. The fungus can be observed in situ, attached by a specialized cell to the beetle hindgut wall. In a recent study of yeast endosymbionts from a variety of beetles, we discovered that E. dimorphus is a member of the Pichia stipitis (Saccharomycetes) clade, known for xylose fermentation and assimilation. The closest relative of E. dimorphus is the PASS1 isolate, repeatedly acquired from passalid beetles in eastern North America from Pennsylvania to Louisiana. In addition to xylose fermentation and assimilation, these yeasts are characterized by the production of hat-shaped ascospores in culture, assimilation of a wide range of sugars, and synthesis of several vitamins. Enteroramus dimorphus, however, can be distinguished from close relatives by several physiological characteristics and rDNA sequences, which vary slightly from the more widespread PASS1 genotype. We present an amended description of E. dimorphus and discuss its symbiotic phase in association with O. disjunctus, including a holdfast that parallels those of unrelated symbiotic yeasts associated with nematodes.

Sugar meal composition of five north central Florida mosquito species (Diptera: Culicidae) as determined by gas chromatography.

Gas chromatography was used to analyze sugars found in individual crops fed on by wild caught adult Anopheles quadrimaculatus s.l. (Say), Coquillettidia perturbans (Walker), Culex nigripalpus Theobald, Culiseta melanura (Coquillett), and Psorophora ferox (von Humboldt) from several north central Florida locations. A wide range of sugars was found, including fructose, glucose, sucrose, maltose, turanose, melezitose, trehalose, raffinose, erlose, and traces of arabinose, rhamnose, and several unknowns. The frequency of individuals testing positive for crop sugars ranged from 9-10% in An. quadrimaculatus and Ps. ferox to 46% in Cq. perturbans. Based on the presence of melezitose or erlose in the crop, honeydew feeding was shown to be an important dietary component in An. quadrimaculatus (57%), Cs. melanura (31%), Cx. nigripalpus (15%), Cq. perturbans (10%), and Ps. ferox (7%). Gas chromatography of crude crop contents is a rapid one-step process that can address important questions such as the source and occurrence of sugar feeding in Diptera. Unique sugar feeding field observations were recorded for several mosquito species.

Biochemical composition of microalgae from the green algal classes Chlorophyceae and Prasinophyceae. 1. Amino acids, sugars and pigments

The biochemical composition of 10 species of green microalgae was determined. The species examined included 3 marine chlorphytes ( Chlorella sp. (CS-247), Chlorella sp. (CS-195) and Stichococcus sp.), and 6 marine prasinophytes ( Pyramimonas cordata, Tetraselmis chui, a temperate and a tropical strain of Micromonas pusilla, Pycnococcus provasolii, and one unidentified coccoid prasinophyte (CS-126)). Pigment composition (e.g. presence of the chlorophyll c-like pigment Mg 2,4 divinyl pheoporphyrin a 5 monomethyl ester (Mg 2,4 D); and lutein, prasinoxanthin or siphonaxanthin-like carotenoids) assisted in the taxonomy of the new strains. One freshwater chlorphyte ( Chlorella protothecoides) was included for comparison. The protein content of all species ranged from 15.2–25.6% of dry weight except for the tropical M. pusilla (5.5%), and carbohydrate ranged from 10.8–16.7% for all species except Chlorella sp. (CS-195) (5.9%). Total lipid varied from 8.5–18.4% of dry weight among the species; chlorophyll a from 0.23–1.54% of dry weight. Amino acid profiles showed only minor variations between species, with the exception of tryptophan and arginine. Two species, Chlorella protothecoides and Chlorella sp. (CS-195) had lower proportions of tryptophan (<0.5% of total amino acids) compared to the other species (1.0–1.8%)while arginine showed large variations across all species ranging from 4.7% (tropical M. pusilla) to 15.0% ( T. chui). Glucose was the dominant sugar in the polysaccharide fraction of eight of the species. Galactose was the major sugar in the unidentified prasinophyte (CS-126) accounting for 54% of sugars. A wide range of sugars was found in Chlorella sp. (CS-195) with glucose making up only 19.3%. The possible use of the species in mariculture, based on their biochemical composition, is also discussed.

ChemInform Abstract: Ethanol Production from Sugars Derived from Plant Biomass by a Novel Fungus.

The concept of transforming renewable plant biomass, and in particular organic waste, to fuels or chemicals continues to attract attention as nonrenewable fossil fuel reserves decrease1,2. Cellulose and hemicellulose, which comprise more than 70% of plant biomass and are the two most abundant organic compounds in the biosphere, occur in the wastes from agriculture and forestry as well as from vegetable and fruit processing and municipal waste treatment. Recycling of these wastes to useful products helps to prevent pollution. After enzymatic or acid hydrolysis, plant biomass yields mostly cellobiose, xylose and glucose together with mannose, galactose and arabinose. Microorganisms which can ferment such a wide range of sugars, at high concentrations, into a high concentration of ethanol have not been reported previously. Here we report on a novel fungus, Paecilomyces sp. NF1, which is capable of fermenting all of the major sugars derived from hydrolysis of plant biomass to ethanol. In xylose fermentation, the ethanol yield of this fungus remained almost unchanged when the concentration of xylose was increased from 20 to 200 g l−1. The fungus also produced good yields of ethanol from glucose, fructose, cellobiose, arabinose, galactose, mannose and ribose, as well as from the simultaneous saccharification and fermentation (SSF) of cellulose with hemicellulose, and from acid hydrolysates of plant biomass.

Ethanol production from sugars derived from plant biomass by a novel fungus

The concept of transforming renewable plant biomass, and in particular organic waste, to fuels or chemicals continues to attract attention as nonrenewable fossil fuel reserves decrease1,2. Cellulose and hemicellulose, which comprise more than 70% of plant biomass and are the two most abundant organic compounds in the biosphere, occur in the wastes from agriculture and forestry as well as from vegetable and fruit processing and municipal waste treatment. Recycling of these wastes to useful products helps to prevent pollution. After enzymatic or acid hydrolysis, plant biomass yields mostly cellobiose, xylose and glucose together with mannose, galactose and arabinose. Microorganisms which can ferment such a wide range of sugars, at high concentrations, into a high concentration of ethanol have not been reported previously. Here we report on a novel fungus, Paecilomyces sp. NF1, which is capable of fermenting all of the major sugars derived from hydrolysis of plant biomass to ethanol. In xylose fermentation, the ethanol yield of this fungus remained almost unchanged when the concentration of xylose was increased from 20 to 200 g l−1. The fungus also produced good yields of ethanol from glucose, fructose, cellobiose, arabinose, galactose, mannose and ribose, as well as from the simultaneous saccharification and fermentation (SSF) of cellulose with hemicellulose, and from acid hydrolysates of plant biomass.

Sugar transport. Properties of mutant bacteria defective in proteins of the phosphoenolpyruvate: sugar phosphotransferase system.

The bacterial phosphotransferase system (PTS) catalyzes the transfer of the phosphoryl group from phosphoenolpyruvate to its sugar substrates, PTS sugars, concomitant with the translocation of these sugars across the bacterial membrane. The phosphorylation of a given sugar requires four proteins, two general proteins, Enzyme I, and the histidine-containing phosphocarrier protein of the PTS (HPr), used for all sugars, and a pair of proteins specific for that sugar, designated an Enzyme II complex. The phosphotransferase system has been implicated in regulating the induction of synthesis of some catabolic enzyme systems required for the utilization of sugars that are not substrates of the phosphotransferase system, and this and the accompanying reports are concerned with this phenomenon in Salmonell typhimurium and Escherichia coli. Mutants defective in Enzyme I (ptsI), HPr (ptsH), and certain Enzymes II were isolated, and their abilities to ferment and grow on a wide range of sugars and other compounds were determined. The mutants showed the expected properties on PTS sugars, but in addition, ptsH and tight ptsI mutants were unable to utilize certain non-PTS sugars, including maltose, melibiose, glycerol, glycerol-P, mannose-6-P, and, in E. coli, lactose. Leaky Enzyme I mutants could utilize these carbohydrates, but were unable to use them in the presence of a PTS sugar such as methyl alpha-D-glucopyranoside. In accord with the results reported by other laboratories, the inability of the mutants to utilize the non-PTS sugars was explained by the fact that these cells could not be normally induced to synthesize the corresponding catabolic enzyme systmes. This phenomenon is designated PTS-mediated repression. PTS-mediated repression was also observed in wild type cells, but by comparing wild type and leaky pts mutants it was shown that the sensitivity to repression by PTS sugars was greatest in mutants containing the lowest levels of Enzyme I or HPr. Furthermore, ptsI mutants containing a second site mutation in a gene for an Enzyme II were not repressed by the sugar substrate of that Enzyme II, although repression by other PTS sugars was not affected. Transport and other studies further indicated that neither appreciable uptake nor metabolism of the PTS sugars was required for these compounds to effect repression. The ptsH mutants showed the same phenotypic properties as the ptsI mutants with some important exceptions. First, they could ferment and grow on a PTS sugar, fructose. Second, after growth on fructose, (and to a lesser extent on glucose or mannose), such mutants were capable of utilizing other PTS sugars for a few generations. Third, growth of the ptsH mutants on fructose relieved PTS-mediated repression; after growth on fructose, but not on lactate, the mutants could grow for several generations on non-PTS sugars. Preliminary experiments indicated that growth on fructose resulted in the formation of one or more proteins that could substitute for HPr in the utilization of both PTS and non-PTS sugars.

THE BIOLOGICAL DECOMPOSITION OF PLANT NATERIALS: PART IX. THE AEROBIC DECOMPOSITION OF HEMICELLULOSES

SUMMARY.1. The decomposition of the hemicelluloses of plant materials occurs rapidly under normal aerobic conditions. Since a number of fungi have been shown by analyses of pure culture rots to be active in fermenting this group, as well as cellulose, some seventy common fungi, mostly Aspergilli and Penicillia, were tested as to their ability to utilise on agar plates the crude hemicellulose from oat straw.2. All of the fungi tested grew reasonably well on the hemicellulose medium, the majority at least as well as on glucose, and a number better than on that sugar. In some cases there was production of a cleared zone round the colony due to an exo‐enzyme. It is likely that ability to ferment hemicelluloses will be found to be a general property of common fungi.3. From soil, manure, and straw, twenty aerobic bacteria were isolated capable of utilising hemicelluloses. Three of these were thermophilic forms. Their morphological characters and biochemical reactions were determined.4. All the organisms utilised a very wide range of sugars and poly‐saccharides; one group produced some acid and gas, the remainder little. Differentiation was obtained on saccharic acid and certain disaccharide acids.5. Five of the mesophilic organisms agreed closely with the description of Achromobacter ubiquitum (Jordan). The remainder were aerobic spore‐formers, though not all Gram‐positive. The negative forms may represent new species.6. None of the organisms in pure culture could validly be described as active in decomposing the isolated hemicellulose, or that in situ in straw.7. Fungi seem to be more active and important in the natural decomposition of hemicelluloses than bacteria, unless when working in association the rather restricted individual fermentative powers of the latter are considerably enhanced.