Sorbitol and Gluconate Production in a Hollow Fibre Membrane Reactor by Immobilized Zymomonas Mobilis

This study describes the results of a hollow fibre membrane reactor with immobilized treated cells of Zymomonas mobilis which produced sorbitol and gluconic acid continuously from fructose and glucose respectively. A productivity of 10-20 g sorbitol · L^-1 · h^-1 and 10-20 gluconate · L^-1 · h^-1 (based on total bioreactor volume) from a feed of 100 g · L^-1 each of glucose and fructose was possible at high dilution rates. Kinetic parameters describing the reaction rate of treated cells in batch reactors were used to analyse the performance of the hollow fibre membrane reactor employing significant convective mass transfer. No significant mass transfer limitation was apparent.     

Syngas fermentation to biofuel: Evaluation of carbon monoxide mass transfer coefficient (kLa) in different reactor configurations

Lignocellulosic biomass such as agri‐residues, agri‐processing by‐products, and energy crops do not compete with food and feed, and is considered to be the ideal renewable feedstocks for biofuel production. Gasification of biomass produces synthesis gas (syngas), a mixture primarily consisting of CO and H₂. The produced syngas can be converted to ethanol by anaerobic microbial catalysts especially acetogenic bacteria such as various clostridia species.One of the major drawbacks associated with syngas fermentation is the mass transfer limitation of these sparingly soluble gases in the aqueous phase. One way of addressing this issue is the improvement in reactor design to achieve a higher volumetric mass transfer coefficient (k_La). In this study, different reactor configurations such as a column diffuser, a 20‐μm bulb diffuser, gas sparger, gas sparger with mechanical mixing, air‐lift reactor combined with a 20‐μm bulb diffuser, air‐lift reactor combined with a single gas entry point, and a submerged composite hollow fiber membrane (CHFM) module were employed to examine the k_La values. The k_La values reported in this study ranged from 0.4 to 91.08 h^?1. The highest k_La of 91.08 h^?1 was obtained in the air‐lift reactor combined with a 20‐μm bulb diffuser, whereas the reactor with the CHFM showed the lowest k_La of 0.4 h^?1. By considering both the k_La value and the statistical significance of each configuration, the air‐lift reactor combined with a 20‐μm bulb diffuser was found to be the ideal reactor configuration for carbon monoxide mass transfer in an aqueous phase. © 2010 American Institute of Chemical Engineers Biotechnol. Prog., 2011     

Continuous succinic acid production from xylose by <Emphasis Type="Italic">Actinobacillus succinogenes</Emphasis>

Continuous, anaerobic fermentations of D-xylose were performed by Actinobacillus succinogenes 130Z in a custom, biofilm reactor at dilution rates of 0.05, 0.10 and 0.30 h^?1. Succinic acid yields on xylose (0.55–0.68 g g^?1), titres (10.9–29.4 g L^?1) and productivities (1.5–3.4 g L^?1 h^?1) were lower than those of a previous study on glucose, but product ratios (succinic acid/acetic acid = 3.0–5.0 g g^?1) and carbohydrate consumption rates were similar. Also, mass balance closures on xylose were up to 18.2 % lower than those on glucose. A modified HPLC method revealed pyruvic acid excretion at appreciable concentrations (1.2–1.9 g L^?1) which improved the mass balance closure by up to 16.8 %. Furthermore, redox balances based on the accounted xylose consumed and the excreted metabolites, indicated an overproduction of reducing power. The oxidative pentose phosphate pathway was shown to be a plausible source of the additional reducing power.     

Optimization of gluconic acid synthesis by removing limitations and inhibitions

The optimization task was performed using the gluconic acid synthesis by the Acetobacter methanolicusMB 58 strain. The microorganisms were grown continuously on methanol as the growth substrate. After finishing the growth process by the deficiency of N and P, the gluconic acid synthesis was started by adding glucose. The synthesis process was performed continuously. The oxygen transfer rate depended on the gluconic acid concentration. During the growth process, the oxygen transfer rate reached a value of about 13 g O₂ · kg^?1 · h^?1using a 30-l glass fermenter equipped with a 6 blade stirrer and fully baffled. This rate declined to a value of between 2 and 5 g O₂ · kg^?1 · h^?1 in the presence of gluconic acid concentrations above 150 g gluconic acid · kg^?1medium. The yield (g gluconic acid · g^?1glucose) depended on the gluconic acid concentration and amounted to y = 0.7 in relation to 150 g gluconic acid · kg^?1medium and y = 0.8 in relation to 200 g · kg^?1medium, respectively. The fermenters were coupled with ultrafiltration moduls (Fa. ROMICON and Fa. SARTORIUS). The biomass concentrations amounted from 5 to 40 g dry mass kg^?1medium. The ultrafiltration modules retained the biomass within the fermentation system. A glucose solution (30 to 50 weight percent glucose) was continuously dosed into the fermenter. The retention time was chosen between 2 and 30 h. The gluconic acid synthesis rate reached values of up to 32 g gluconic acid · kg^?1 · h^?1. Within a range of up to 250 g gluconic acid · kg^?1medium, the acid concentration had no influence on the enzyme activity.     

A study of polynucleotide phosphorylase production by <Emphasis Type="Italic">Escherichia coli</Emphasis> in a hollow fibre reactor

A 30-l hollow fibre reactor with continuous fermentation for cell recycling of Escherichia coli AS 1.183 was used to remove the inhibitory effects on cell growth and extend the fast growth phase to increase the yield of polynucleotide phosphorylase (PNPase) in E. coli cells. When the dilution rate was 1.5 h⁻¹, the cell concentration of E. coli reached 235 g/l (wet wt, 70% moisture content), with PNPase activity above 90 u/g (wet wt). With the dilution rate is 1.0 h⁻¹, the fermentor volumetric productivity of PNPase in a hollow fiber reactor can reach 974 (u/h * l) compared to 20 (u/h * l) in a conventional batch culture.     

Production of sorbitol and gluconic acid by permeabilized cells of Zymomonas mobilis

Summary Zymomonas mobilis is able to convert glucose and fructose to gluconic acid and sorbitol. The enzyme, glucose-fructose oxidoreductase, catalysing the intermolecular oxidation-reduction of glucose and fructose to gluconolactone and sorbitol, was formed in high amounts [1.4 units (U)·mg^-1] when Z. mobilis was grown in chemostats with glucose as the only carbon source under non-carbon-limiting conditions. The activity of a gluconolactone-hydrolysing lactonase was constant at 0.2 U·mg^-1. Using glucose-grown cells for the conversion of equimolar fructose and glucose mixtures up to 60% (w/v), a maximum product concentration of only 240 g·1^-1 of sorbitol was found. The gluconic acid accumulated was further metabolized to ethanol. After permeabilizing the cells using cationic detergents, maximum sorbitol and gluconic acid concentrations of 295 g·1^-1 each were reached; no ethanol production occurred. In a continuous process with -carrageenan-immobilized and polyethylenimin-hardened, permeabilized cells no significant decrease in the conversion yield was observed after 75 days. The specific production rates for a high yield conversion ( > 98%) in a continuous two-stage process were 0.19 g·g^-1·h^-1 for sorbitol and 0.21 g·g^-1·h^-1 for gluconic acid, respectively. For the sugar conversion of cetyltrimethylammonium bromide-treated -carrageenan-immobilized cells a V _max of 1.7 g·g^-1·h^-1 for sorbitol production and a K _m of 77.2 g·1^-1 were determinedOffprint requests to: B. Rehr     

Enzymatic preparation of fatty acid esters of sugar alcohols by condensation in acetone using a packed-bed reactor with immobilized Candida antarctica lipase

Mono- and dilauroyl arabitols, ribitols, xylitols and sorbitols were synthesized batchwise or continuously at 50°C or 60°C by condensation catalyzed by an immobilized Candida antarctica lipase in acetone. Continuous production was realized using a system where a column packed with sugar alcohol and a packed-bed reactor with the immobilized lipase were connected in series. The concentrations of the mono- and dilauroyl esters of each sugar alcohol became almost constant at mean residence times of 15 min or longer in the packed-bed reactor. The monolauroyl, monomyristoyl and monopalmytoyl arabitols, ribitols, xylitols and sorbitols were continuously produced using the reactor system at 60°C, and the productivity was in the range of 1.3–2.0 kg L^?1-reactor·day except for the fatty acid esters of sorbitol, the productivity of which was 0.6–0.8 kg L^?1-reactor·day.     

PHYSIOLOGICAL INDICATORS OF NUTRIENT DEFICIENCY IN CLADOPHORA (CHLOROPHYTA) IN THE CLARK FORK OF THE COLUMBIA RIVER,MONTANA1

Cellular nutrient concentrations and nutrient uptake rates of Cladophora glomerata (L.) Kuetzing were determined during summer and fall in 1989–1990 at a site on the upper Clark Fork of the Columbia River, Montana. Both physiological tests indicated that Cladophora growth is likely to be limited by nitrogen during late summer-early fall. Maximum uptake rates of ammonia-N and nitrate-N were 5935–6991 and 507–984 μg · g DW^?1· h^?1, respectively, during July–October when dissolved inorganic nitrogen (DIN) concentrations in the river were less than 10 μg · L^?1. During November-December, when DIN was 72–376 μg · L^?1, maximum ammonia-N uptake was 1137–1633 μg · g DW^?1· h^?1 and maximum nitrate-N uptake was 0–196 μg · g DW^?1· h^?1. Cellular nitrogen during summer–early fall was 0.78–1.80% of Cladophora dry weight, frequently at or below 1.1%, a level suggested as a critical minimum N concentration for maximum growth. In contrast, cellular P was 0.18–0.36% of dry weight, 3–6 times the suggested critical P concentration of 0.06%. Molar ratios of cellular N:P (< 16:1) and DIN: SRP (< 4:1) during late summer-early fall also indicated potential N limitation. Cellular N and P from Cladophora collected from a second site influenced by a municipal wastewater discharge in 1990 displayed similar seasonal trends. At both sites, seasonal fluctuations in DIN were closely tracked by changes in cellular N, Cellular P, however, increased through the growing season despite declining levels of SRP in the river.     

Improvement of a mammalian cell culture process by adaptive,model-based dialysis fed-batch cultivation and suppression of apoptosis

Both conventional and genetic engineering techniques can significantly improve the performance of animal cell cultures for the large-scale production of pharmaceutical products. In this paper, the effect of such techniques on cell yield and antibody production of two NS0 cell lines is presented. On the one hand, the effect of fed-batch cultivation using dialysis is compared to cultivation without dialysis. Maximum cell density could be increased by a factor of ~5–7 by dialysis fed-batch cultivation. On the other hand, suppression of apoptosis in the NS0 cell line 6A1 bcl-2 resulted in a prolonged growth phase and a higher viability and maximum cell density in fed-batch cultivation in contrast to the control cell line 6A1 (100)3. These factors resulted in more product formation (by a factor ~2). Finally, the adaptive model-based OLFO controller, developed as a general tool for cell culture fed-batch processes, was able to control the fed-batch and dialysis fed-batch cultivations of both cell lines.Abbreviations A membrane area (dm²) - c _Glc,F glucose concentration in nutrient feed (mmol L^–1) - c _Glc,FD glucose concentration in dialysis feed (mmol L^–1) - c _Glc,i glucose concentration in inner reactor chamber (mmol L^–1) - c _Glc,o glucose concentration in outer reactor chamber (dialysis chamber) (mmol L^–1) - c _Lac,FD lactate concentration in dialysis feed (mmol L^–1) - c _Lac,i lactate concentration in inner reactor chamber (mmol L^–1) - c _Lac,o lactate concentration in outer reactor chamber (dialysis chamber) (mmol L^–1) - c _LS,FD limiting substrate concentration in dialysis feed (mmol L^–1) - c _LS,i limiting substrate concentration in inner reactor chamber (mmol L^–1) - c _LS,o limiting substrate concentration in outer reactor chamber (dialysis chamber) (mmol L^–1) - c _Mab monoclonal antibody concentration (mg L^–1) - F _D feed rate of dialysis feed (L h^–1) - F _Glc feed rate of nutrient concentrate feed (L h^–1) - K _d maximum death constant (h^–1) - k _d,LS death rate constant for limiting substrate (mmol L^–1) - k _Glc monod kinetic constant for glucose uptake (mmol L^–1) - k _Lac monod kinetic constant for lactate uptake (mmol L^–1) - k _LS monod kinetic constant for limiting substrate uptake (mmol L^–1) - K _Lys cell lysis constant (h^–1) - K _S,Glc monod kinetic constant for glucose (mmol L^–1) - K _S,LS monod kinetic constant for limiting substrate (mmol L^–1) - µ cell-specific growth rate (h^–1) - µ _d cell-specific death rate (h^–1) - µ _d,min minimum cell-specific death rate (h^–1) - µ _max maximum cell-specific growth rate (h^–1) - P _Glc membrane permeation coefficient for glucose (dm h^–1) - P _Lac membrane permeation coefficient for lactate (dm h^–1) - P _LS membrane permeation coefficient for limiting substrate (dm h^–1) - q _Glc cell-specific glucose uptake rate (mmol cell^–1 h^–1) - q _Glc,max maximum cell-specific glucose uptake rate (mmol cell^–1 h^–1) - q _Lac cell-specific lactate uptake/production rate (mmol cell^–1 h^–1) - q _Lac,max maximum cell-specific lactate uptake rate (mmol cell^–1 h^–1) - q _LS cell-specific limiting substrate uptake rate (mmol cell^–1 h^–1) - q _LS,max maximum cell-specific limiting substrate uptake rate (mmol cell ^–1 h^–1) - q _Mab cell-specific antibody production rate (mg cell^–1 h^–1) - q _MAb,max maximum cell-specific antibody production rate (mg cell^–1 h^–1) - t time (h) - V _i volume of inner reactor chamber (culture chamber) (L) - V _o volume of outer reactor chamber (dialysis chamber) (L) - X _t total cell concentration (cells L^–1) - X viable cell concentration (cells L^–1) - Y _Lac/Glc kinetic production constant (stoichiometric ratio of lactate production and glucose uptake) (–)     

Butanol production from concentrated lactose/whey permeate: Use of pervaporation membrane to recover and concentrate product

In these studies, butanol (acetone butanol ethanol or ABE) was produced from concentrated lactose/whey permeate containing 211 g L^?1 lactose. Fermentation of such a highly concentrated lactose solution was possible due to simultaneous product removal using a pervaporation membrane. In this system, a productivity of 0.43 g L^?1 h^?1 was obtained which is 307 % of that achieved in a non-product removal batch reactor (0.14 g L^?1 h^?1) where approximately 60 g L^?1 whey permeate lactose was fermented. The productivity obtained in this system is much higher than that achieved in other product removal systems (perstraction 0.21 g L^?1 h^?1 and gas stripping 0.32 g L^?1 h^?1). This membrane was also used to concentrate butanol from approximately 2.50 g L^?1 in the reactor to 755 g L^?1. Using this membrane, ABE selectivities and fluxes of 24.4–44.3 and 0.57–4.05 g m^?2 h^?1 were obtained, respectively. Pervaporation restricts removal of water from the reaction mixture thus requiring significantly less energy for product recovery when compared to gas stripping.     

Ethanol production by immobilized whole cells ofZymomonas mobilis in a continuous flow expanded bed bioreactor and a continuous flow stirred tank bioreactor

Continuous ethanol fermentation by immobilized whole cells ofZymomonas mobilis was investigated in an expanded bed bioreactor and in a continuous stirred tank reactor at glucose concentrations of 100, 150 and 200 g L^–1. The effect of different dilution rates on ethanol production by immobilized whole cells ofZymomonas mobilis was studied in both reactors. The maximum ethanol productivity attained was 21 g L^–1 h^–1 at a dilution rate of 0.36 h^–1 with 150 g glucose L^–1 in the continuous expanded bed bioreactor. The conversion of glucose to ethanol was independent of the glucose concentration in both reactors.     

The effect of carbon source on callus induction and regeneration ability in Pharbitis nil

Flower buds, cotyledons and hypocotyls of Pharbitis nil were used as plant material. Flower buds (1–2 mm long) were excised from 3-week-old plants, grown in soil. Cotyledons of 7-day-old sterile seedlings were cut into 25 mm² squares cotyledons whereas hypocotyls were cut to 1 mm long fragments. Explants were transferred into Petri dishes containing the Murashige and Skoog medium (MS), supplemented with either BA (11 μM·L⁻¹) alone or BA (22 μM·L⁻¹) and NAA (0.55 μM·L⁻¹), and different sugars: sucrose, fructose, glucose, mannose or sorbitol (autoclaved or filter-sterilized). Addition of glucose instead of sucrose to the medium stimulated the induction of callus on flower buds and cotyledonary explants, but inhibited its growth on fragments of hypocotyls. The medium supplemented with fructose (especially filter-sterilized) stimulated the development of flower elements. Organogenesis of shoots and roots on explants was also observed. Flower buds and hypocotyls were able to regenerate both organs. Addition of fructose or glucose to the medium stimulated the organogenesis of shoots, whereas root organogenesis was inhibited on all explants used. Sorbitol strongly inhibited both induction of callus and organogenesis on all explants used.     

137Cs penetration by contact exchange through isolated plant cuticles: cuticles as asymmetric transport membranes

The penetration of ¹³⁷Cs by contact exchange through cuticular membranes from the adaxial surface of leaves of Pyrus communis and Prunus cerasus has been investigated. The resistance of the cuticles to the caesium penetration was dependent on the counter-ions associated with the fixed negative ion exchange sites in the membrane. The mobility of hydrated potassium ions and their tenuous connection to -COOH^?-groups in the membrane encouraged caesium permeation in contrast to cuticular membranes with predominantly protonized ion exchange sites. Divalent calcium ions caused a strong reduction (4–20 times) of the caesium permeability which is decisive for the calculation of the caesium uptake by the intact leaf. Under these conditions, a penetration rate of the deposited caesium of 0·11±0·05% h^?1 for pear cuticles and of 0·036±0·025% h^?1 for cherry cuticles was measured after the adjustment to steady state conditions. Approximately 12–24% and 4·5–7·5% of initially retained caesium could be absorbed by the leaves of pear and cherry, respectively, in a rain-free period of 7 d in the area of Munich after wet deposition of fallout from the Chernobyl reactor accident. Furthermore, the caesium penetration from the physiological inside to the outside of the membrane was found to be smaller by a factor of 100–150 compared with that of the opposite direction.     

Zymomonas mobilis mutants blocked in fructose utilization

Summary A mutant ofZymomonas mobilis deficient in the utilization of fructose for growth and ethanol formation was shown to lack fructokinase activity. When grown in media which contained glucose+fructose or sucrose, both the mutant and wild type produced sorbitol in amounts up to 60 g·l^-1, depending on the initial concentrations of sugars. Sorbitol formation was accompanied by an accumulation of acetaldehyde, gluconate, and acetoin. A ferricyanide-dependent sorbitol dehydrogenase could be localized in the cell membrane; it thus resembles the sorbitol dehydrogenase ofGluconobacter suboxydans. Neither a NAD(P)H dependent reduction of fructose nor a NAD(P) dependent dehydrogenation of sorbitol could be detected in cell-free extracts. The use of fructose-negative mutants ofZ. mobilis for the enrichment of fructose in glucose+fructose mixtures is discussed.     

Acetone–butanol–ethanol production with high productivity using Clostridium acetobutylicum BKM19

Conventional acetone–butanol–ethanol (ABE) fermentation is severely limited by low solvent titer and productivities. Thus, this study aims at developing an improved Clostridium acetobutylicum strain possessing enhanced ABE production capability followed by process optimization for high ABE productivity. Random mutagenesis of C. acetobutylicum PJC4BK was performed by screening cells on fluoroacetate plates to isolate a mutant strain, BKM19, which exhibited the total solvent production capability 30.5% higher than the parent strain. The BKM19 produced 32.5 g L^?1 of ABE (17.6 g L^?1 butanol, 10.5 g L^?1 ethanol, and 4.4 g L^?1 acetone) from 85.2 g L^?1 glucose in batch fermentation. A high cell density continuous ABE fermentation of the BKM19 in membrane cell‐recycle bioreactor was studied and optimized for improved solvent volumetric productivity. Different dilution rates were examined to find the optimal condition giving highest butanol and ABE productivities. The maximum butanol and ABE productivities of 9.6 and 20.0 g L^?1 h^?1, respectively, could be achieved at the dilution rate of 0.85 h^?1. Further cell recycling experiments were carried out with controlled cell‐bleeding at two different bleeding rates. The maximum solvent productivities were obtained when the fermenter was operated at a dilution rate of 0.86 h^?1 with the bleeding rate of 0.04 h^?1. Under the optimal operational condition, butanol and ABE could be produced with the volumetric productivities of 10.7 and 21.1 g L^?1 h^?1, and the yields of 0.17 and 0.34 g g^?1, respectively. The obtained butanol and ABE volumetric productivities are the highest reported productivities obtained from all known‐processes. Biotechnol. Bioeng. 2013; 110: 1646–1653. © 2013 Wiley Periodicals, Inc.     

Improving mass transfer in an inclined tubular photobioreactor

The mass transfer and hydrodynamics of two outdoor tubular photobioreactor designs were compared, a Tredici-design near-horizontal tubular photobioreactor (NHTR) and an enhanced version of this reactor (ENHTR), for the purpose of improving algal growth via improved hydrodynamics. The enhancements included addition of vertical bubble columns at the sparger end and a larger degasser with a diffuser. Gas-liquid mass transfer and other performance measures were assessed for a range of gas sparging rates. The ENHTR modifications proved to be very successful, increasing oxygen stripping and carbon dioxide dissolution by 120–220 % and 0–50 %, respectively. There was an increase in axial mixing and a fourfold decrease in total mixing time. Experiments were conducted to determine that approximately 50 % of the mass transfer occurred in the vertical bubble columns, while 85–90 % of the mass transfer in the near-horizontal tubes occurred in the lower half of the tubes. These improvements can lead to increased algae productivity depending upon culture-specific parameters. The theoretical maximum productivity of a hypothetical algal culture would be 1.6 g m^?2 h^?1 in the NHTR, and we have previously achieved a maximum of 1.5 g m^?2 h^?1 growing Arthrospira at densities up to 7.5 g L^?1 in this reactor. Due to enhanced mass transfer in the ENHTR, the predicted maximum productivity should increase to 4.75 g m^?2 h^?1. The potential for further improvements in productivity due to various additional enhancements is described.     

Maximum sustainable speed, energetics and swimming kinematics of a tropical carangid fish, the green jack Caranx caballus

Maximum sustained swimming speeds, swimming energetics and swimming kinematics were measured in the green jack Caranx caballus (Teleostei: Carangidae) using a 41 l temperature‐controlled, Brett‐type swimming‐tunnel respirometer. In individual C. caballus [mean ±s.d. of 22·1 ± 2·2 cm fork length (L_F), 190 ± 61 g, n = 11] at 27·2 ± 0·7° C, mean critical speed (U_crit) was 102·5 ± 13·7 cm s^?1 or 4·6 ± 0·9 L_F s^?1. The maximum speed that was maintained for a 30 min period while swimming steadily using the slow, oxidative locomotor muscle (U_max,c) was 99·4 ± 14·4 cm s^?1 or 4·5 ± 0·9 L_F s^?1. Oxygen consumption rate (M in mg O₂ min^?1) increased with swimming speed and with fish mass, but mass‐specific M (mg O₂ kg^?1 h^?1) as a function of relative speed (L_F s^?1) did not vary significantly with fish size. Mean standard metabolic rate (R_S) was 170 ± 38 mg O₂ kg^?1 h^?1, and the mean ratio of M at U_max,c to R_S, an estimate of factorial aerobic scope, was 3·6 ± 1·0. The optimal speed (U_opt), at which the gross cost of transport was a minimum of 2·14 J kg^?1 m^?1, was 3·8 L_F s^?1. In a subset of the fish studied (19·7–22·7 cm L_F, 106–164 g, n = 5), the swimming kinematic variables of tailbeat frequency, yaw and stride length all increased significantly with swimming speed but not fish size, whereas tailbeat amplitude varied significantly with speed, fish mass and L_F. The mean propulsive wavelength was 86·7 ± 5·6 %L_F or 73·7 ± 5·2 %L_T. Mean ±s.d . yaw and tailbeat amplitude values, calculated from lateral displacement of each intervertebral joint during a complete tailbeat cycle in three C. caballus (19·7, 21·6 and 22·7 cm L_F; 23·4, 25·3 and 26·4 cm L_T), were 4·6 ± 0·1 and 17·1 ± 2·2 %L_T, respectively. Overall, the sustained swimming performance, energetics, kinematics, lateral displacement and intervertebral bending angles measured in C. caballus were similar to those of other active ectothermic fishes that have been studied, and C. caballus was more similar to the chub mackerel Scomber japonicus than to the kawakawa tuna Euthynnus affinis.     

Myotube production in fast myotomal muscle is switched-off at shorter body lengths in male than female Atlantic halibut Hippoglossus hippoglossus (L.) resulting in a lower final fibre number

A sampling method is described to determine accurately the number of fast myotomal muscle fibres (N_F) in a large flatfish species, the Atlantic halibut Hippoglossus hippoglossus. An unusual feature of the fast myotomal muscle is the presence of internalized strips of slow muscle fibres. In fish of 1·5–3·5 kg (n = 24), the total cross‐sectional area (A_TC) of fast muscle was 18% greater in the dorsal than ventral myotomal compartments (P < 0·05), whereas there was no significant difference between left‐ and right‐hand sides of the body. Due the bilateral asymmetry, muscle blocks (5 × 5 × 5 mm) were prepared to systematically sample each myotomal quadrant (dorsal, ventral, left‐ and right‐side) and the diameters of 150 fast fibres measured per block. Smooth non‐parametric probability functions were fitted to a minimum of 800 measurements of fibre diameter per quadrant (n = 5). There were no significant differences in the distribution of muscle fibre diameters between myotomal compartments and therefore N_F could be estimated from a single quadrant. The number of blocks required to estimate N_F with a repeatability of ±2·5% increased from six at 300 g body mass to 17 at 96·5 kg, caused by variation within and between blocks. Gompertz curves were fitted to measurements of fibre number and fork length (L_F). The estimated final fibre number was 8·96 × 10⁵ (7·99–9·94 × 10⁵, 95% CI) for males and 1·73 × 10⁶ (1·56–1·90 × 10⁶, 95% CI) for female fish. The estimated L_F for cessation of fibre recruitment in the fast muscle of female fish (1775 mm) was almost twice that in males (810 mm), reflecting their greater ultimate body size.     

High solid fed‐batch butanol fermentation with simultaneous product recovery: Part II—process integration

In these studies, liquid hot water (LHW) pretreated and enzymatically hydrolyzed Sweet Sorghum Bagasse (SSB) hydrolyzates were fermented in a fed‐batch reactor. As reported in the preceding paper, the culture was not able to ferment the hydrolyzate I in a batch process due to presence of high level of toxic chemicals, in particular acetic acid released from SSB during the hydrolytic process. To be able to ferment the hydrolyzate I obtained from 250 g L^?1 SSB hydrolysis, a fed‐batch reactor with in situ butanol recovery was devised. The process was started with the hydrolyzate II and when good cell growth and vigorous fermentation were observed, the hydrolyzate I was slowly fed to the reactor. In this manner the culture was able to ferment all the sugars present in both the hydrolyzates to acetone butanol ethanol (ABE). In a control batch reactor in which ABE was produced from glucose, ABE productivity and yield of 0.42 g L^?1 h^?1 and 0.36 were obtained, respectively. In the fed‐batch reactor fed with SSB hydrolyzates, these productivity and yield values were 0.44 g L^?1 h^?1 and 0.45, respectively. ABE yield in the integrated system was high due to utilization of acetic acid to convert to ABE. In summary we were able to utilize both the hydrolyzates obtained from LHW pretreated and enzymatically hydrolyzed SSB (250 g L^?1) and convert them to ABE. Complete fermentation was possible due to simultaneous recovery of ABE by vacuum. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:967–972, 2018     

Effects of surgically implanted acoustic transmitters >2% of body mass on the swimming performance, survival and growth of juvenile sockeye and Chinook salmon

The influence of surgical implantation of an acoustic transmitter on the swimming performance, growth and survival of juvenile sockeye salmon Oncorhynchus nerka and Chinook salmon Oncorhynchus tshawytscha was examined. The transmitter had a mass of 0·7 g in air while sockeye salmon had a mass of 7·0–16·0 g and Chinook salmon had a mass of 6·7–23·1 g (a transmitter burden of 4·5–10·3% for sockeye salmon and 3·1–10·7% for Chinook salmon). Mean critical swimming speeds (U_crit) for Chinook salmon ranged from 47·5 to 51·2 cm s^?1 [4·34–4·69 body lengths (fork length, L_F) s^?1] and did not differ among tagged, untagged and sham‐tagged groups. Tagged sockeye salmon, however, did have lower U_crit than control or sham fish. The mean U_crit for tagged sockeye salmon was 46·1 cm s^?1 (4·1 L_F s^?1), which was c. 5% less than the mean U_crit for control and sham fish (both groups were 48·6 cm s^?1 or 4·3 L_F s^?1). A laboratory evaluation determined that there was no difference in L_F or mass among treatments (control, sham or tag) either at the start or at the end of the test period, suggesting that implantation did not negatively influence the growth of either species. None of the sockeye salmon held under laboratory conditions died from the influence of surgical implantation of transmitters. In contrast, this study found that the 21 day survival differed between tagged and control groups of Chinook salmon, although this result may have been confounded by the poor health of Chinook salmon treatment groups.