Effect of deltamethrin on the gills of Aphanius dispar: a microscopic study

Aphanius dispar, a freshwater fish (mean total length ± sd, 3.42 ± 0.33 cm) was exposed to different concentrations of deltamethrin (2.25, 2.50 and 3.00 μg L⁻¹), an insecticide used to control Dubas bug, Ommatissus lybicus in Oman. The histopathological changes in the structure of the gills in fish exposed to deltamethrin was studied using light, transmission and scanning electron microscopy. In light microscopy, the fish exposed to 2.25 μg L⁻¹ deltamethrin, showed hypertrophy and hyperplasia of chloride cells, while in 2.50 μg L⁻¹, additional changes like vacuolization, lifting of the lamellar epithelium and fusion of secondary lamellae were observed. The most severe alteration including vacuolization, desquamation of cells and dilation of intercellular space was recorded at 3.00 μg L⁻¹. Transmission and scanning electron microscopy, supports the findings of light microscopy and further document the ultrastructural damage caused, especially in exposure to 2.50 and 3.00 μg L⁻¹. Al l changes observed are described in detail. The deltamethrin exposure concentration of 2.25 μg L⁻¹ seems to be a threshold above which any small increase in concentration results in severe damage. All present results have been compared with those of previous studies on gill damage caused by various chemical substances. The impacts of the damage on the functioning of gills as a respiratory organ are discussed.     

Toxicity of lead and zinc to developing mussel and sea urchin embryos: Critical tissue residues and effects of dissolved organic matter and salinity

Lead (Pb) EC50 values in the very sensitive early development phases (48–72 h post-fertilization) of the mussels Mytilus galloprovincialis and Mytilus trossolus and sea urchin Strongylocentrotus purpuratus in 100% sea water were: M. trossolus — 45 (95% C.I. = 22–72) μg L^− 1; M. galloprovincialis — 63 (36–94) μg L^− 1; S. purpuratus — 74 (50–101) μg L^− 1. Salinity thresholds for normal development varied: M. trossolus > 21 ppt; M. galloprovincialis > 28 ppt; S. purpuratus ≥ 30 ppt. Addition of two spectroscopically distinct dissolved organic matters (DOM) from fresh water (Nordic Reservoir) and sea water (Inshore) moderately decreased the toxicity of Pb to both mussels, but not in a concentration-dependent fashion, with only an approximate doubling of EC50 over the range of 1.4–11.2 mg C L^− 1. Independent Pb binding capacity determinations for DOC explained the lack of a relationship between DOM concentration and toxicity. Salinity had no effect on Pb toxicity down to 21 ppt in M. trossolus, and low salinity (21 ppt) did not enhance the protective effect of DOC. Both DOMs increased the toxicity of Pb in developing sea urchin embryos, in contrast to mussels. Relative to Pb, the organisms were 6–9 fold less sensitive to Zn on a molar basis in 100% seawater with the following Zn EC50s: M. trossolus — 135 (103–170) μg L^− 1; M. galloprovincialis — 172 (126–227) μg L^− 1, S. purpuratus — 151 (129–177) μg L^− 1. Nordic Reservoir and Inshore DOM (2–12 mg C L^− 1) had no significant effect on Zn toxicity to mussels, in accord with voltammetry data showing an absence of any strong ligand binding for Zn by DOMs. As with Pb, DOMs increased Zn toxicity to urchin larvae. Critical Tissue Residues (CTR) based on whole body concentrations of Pb and Zn were determined for M. galloprovincialis at 48 h and S. purpuratus at 72 h. The median lethal CTR values (LA50s), useful parameters for development of saltwater Biotic Ligand Models (BLMs), were approximately 4-fold higher on a molar basis for Zn than for Pb. The latter were not altered by DOM exposure, despite increased EC50 values, in accord with the tenets of the BLM.     

Development of chemically defined media supporting high cell density growth of Ketogulonicigenium vulgare and Bacillus megaterium

The immediate precursor of L-ascorbic acid, or vitamin C, is 2-keto-l-gulonic acid (2-KLG). This is commonly produced commercially by Ketogulonicigenium vulgare and Bacillus megaterium, using corn steep liquor powder (CSLP) as an organic nitrogen source. In this study, the effects of the individual CSLP components (amino acids, vitamins, and metal elements) on 2-KLG production were evaluated, with the aim of developing a complete, chemically defined medium for 2-KLG production. Forty components of CSLP were analyzed, and key components were correlated to biomass, 2-KLG productivity, and consumption rate of L-sorbose. Glycine had the greatest effect, followed by serine, biotin, proline, nicotinic acid, and threonine. The combination of 0.28 g L⁻¹ serine, 0.36 g L⁻¹glycine, 0.18 g L⁻¹ threonine, 0.28 g L⁻¹proline, 0.19 g L⁻¹nicotinic acid, and 0.62 mg L⁻¹biotin in a chemically defined medium produced the highest maximum biomass concentration (4.2 × 10⁹ cfu mL⁻¹), 2-KLG concentration (58 g L⁻¹), and yield (0.76 g g⁻¹) after culturing for 28 h.     

pH-control modes in a 5-L stirred-tank bioreactor for cell biomass and exopolysaccharide production by Tremella fuciformis spore

The effect of pH-control modes on cell growth and exopolysaccharide production by Tremella fuciformis was evaluated in a 5-L bioreactor. The results show that the maximal dry cell weight (DCW) and exopolysaccharide production were 23.57 and 4.48 g L⁻¹ in pH-stat fermentation, where the maximal specific growth rate (μ_max) and specific production rate of exopolysaccharide (P_P/X) were 1.03 and 0.24 d⁻¹, respectively; under pH-shift cultivation, the maximal DCW and exopolysaccharide production were 30.57 and 3.90 g L⁻¹, where the μ_max and P_P/X were 1.21 and 0.06 d⁻¹. Unlike batch fermentation, maximal DCW and exopolysaccharide production merely reached 15.04 and 2.0 g L⁻¹, where the μ_max and P_P/X were 0.86 and 0.05 d⁻¹, respectively. These results suggest that a pH-stat strategy is a more efficient way of performing the fermentation process to increase exopolysaccharide production. Furthermore, this research has also proved that the three-stage pH-control mode is effective for cell growth.     

Cultivation of microalgae for oil production with a cultivation strategy of urea limitation

The microalgae, Chlorella sp., were cultivated in various culture modes to assess biomass and lipid productivity in this study. In the batch mode, the biomass concentrations and lipid content of Chlorella sp. cultivated in a medium containing 0.025–0.200 g L⁻¹ urea were 0.464–2.027 g L⁻¹ and 0.661–0.326 g g⁻¹, respectively. The maximum lipid productivity of 0.124 g d⁻¹ L⁻¹ occurred in a medium containing 0.100 g L⁻¹ urea. In the fed-batch cultivation, the highest lipid content was obtained by feeding 0.025 g L⁻¹ of urea during the stationary phase, but the lipid productivity was not significantly increased. However, a semi-continuous process was carried out by harvesting the culture and renewing urea at 0.025 g L⁻¹ each time when the cultivation achieved the early stationary phase. The maximum lipid productivity of 0.139 g d⁻¹ L⁻¹ in the semi-continuous culture was highest in comparison with those in the batch and fed-batch cultivations.     

In silico optimization and low structured kinetic model of poly[(R)-3-hydroxybutyrate] synthesis by Cupriavidus necator DSM 545 by fed-batch cultivation on glycerol

Glycerol was utilized by Cupriavidus necator DSM 545 for production of poly-3-hydroxybutyrate (PHB) in fed-batch fermentation. Maximal specific growth rates (0.12 and 0.3 h⁻¹) and maximal specific non-growth PHB production rate (0.16 g g⁻¹ h⁻¹) were determined from two experiments (inocula from exponential and stationary phase). Saturation constants for nitrogen (0.107 and 0.016 g L⁻¹), glycerol (0.05 g L⁻¹), non-growth related PHB synthesis (0.011 g L⁻¹) and nitrogen/PHB related inhibition constant (0.405 g L⁻¹), were estimated. Five relations for specific growth rate were tested using mathematical models. In silico performed optimization procedures (varied glycerol/nitrogen ratio and feeding) has resulted in a PHB content of 70.9%, shorter cultivation time (23 h) and better PHB yield (0.347 g g⁻¹). Initial concentration of biomass 16.8 g L⁻¹ and glycerol concentration in broth between 3 and 5 g L⁻¹ were decisive factors for increasing of productivity.     

3-Phenyllactic acid production by substrate feeding and pH-control in fed-batch fermentation of Lactobacillus sp. SK007

3-Phenyllactic acid (PLA), which is produced by some strains of lactic acid bacteria (LAB), is a known antimicrobial agent with a broad spectrum. Batch and fed-batch fermentation by the strain Lactobacillus sp. SK007 for PLA production have been reported. With batch fermentation without pH-control, PLA production yield was 2.42 g L⁻¹. When fed-batch fermentation by Lactobacillus sp. SK007 was conducted in 3 L initial volume with pH-control at 6.0 and intermittent feeding, which was developed after fermentation for 12 h and every 2 h with 120 mL 100 g L⁻¹ PPA phenylpyruvic acid (PPA) and 50 mL 500 g L⁻¹ glucose each time, PLA production yield reached 17.38 g L⁻¹. The final conversion ratio of PPA to PLA was 51.1%, and the PLA production rate was 0.241 g L⁻¹ h⁻¹. This indicated that PPA was the ideal substrate for PLA fermentation production, and fed-batch fermentation with intermittent PPA feeding and pH-control was an effective approach to improve PLA production yield.     

Development of an industrial ethanol-producing yeast strain for efficient utilization of cellobiose

The BGL1 gene, encoding β-glucosidase in Saccharomycopsis fibuligera, was intracellular, secreted or cell-wall associated expressed in an industrial strain of Saccharomyces cerevisiae. The obtained recombinant strains were studied under aerobic and anaerobic conditions. The results indicated that both the wild type and recombinant strain expressing intracellular β-glucosidase cannot grow in medium using cellobiose as sole carbon source. As for the recombinant EB1 expressing secreted enzyme and WB1 expressing cell-wall associated enzyme, the maximum specific growth rates (μ_max) could reach 0.03 and 0.05 h⁻¹ under anaerobic conditions, respectively. Meanwhile, the surface-engineered S. cerevisiae utilized 5.2 g cellobiose L⁻¹ and produced 2.3 g ethanol L⁻¹ in 48 h, while S. cerevisiae secreting β-glucosidase into culture broth used 3.6 g cellobiose L⁻¹ and produced 1.5 g ethanol L⁻¹ over the same period, but no-full depletion of cellobiose were observed for both the used recombinant strains. The results suggest that S. cerevisiae used in industrial ethanol production is deficient in cellobiose transporter. However, when β-glucoside permease and β-glucosidase were co-expressed in this strain, it could uptake cellobiose and showed higher growth rate (0.11 h⁻¹) on cellobiose.     

Vertical tubular photobioreactor for semicontinuous culture of Cyanobium sp

We evaluated the kinetic culture characteristics of the microalgae Cyanobium sp. grown in vertical tubular photobioreactor in semicontinuous mode. Cultivation was carried out in vertical tubular photobioreactor for 2 L, in 57 d, at 30 °C, 3200 Lux, and 12 h light/dark photoperiod. The maximum specific growth rate was found as 0.127 d⁻¹, when the culture had blend concentration of 1.0 g L⁻¹, renewal rate of 50%, and sodium bicarbonate concentration of 1.0 g L⁻¹. The maximum values of productivity (0.071 g L⁻¹ d⁻¹) and number of cycles (10) were observed in blend concentration of 1.0 g L⁻¹, renewal rate of 30%, and bicarbonate concentration of 1.0 g L⁻¹. The results showed the potential of semicontinuous cultivation of Cyanobium sp. in closed tubular bioreactor, combining factors such as blend concentration, renewal rate, and sodium bicarbonate concentration.     

Metallothioneins and trace elements in digestive gland,gills, kidney and gonads of Octopus vulgaris

Metallothionein-like proteins (MT) and V, Cr, Co, Ni, Zn, Cu, As and Cd were determined in digestive gland, gills, kidney and gonads of Octopus vulgaris, from the Portuguese coast. To our knowledge these are the first data on MT in octopus. High concentrations (µg g^− 1, dry mass) of Zn (48050) and Cd (555) were found in digestive gland, and MT reached levels one order of magnitude above the ones registered in wild bivalves. Significantly higher levels of MT in digestive gland and gills of specimens from A and B were in line with elevated Cd concentrations. Principal component analyses (PCA) point to MT-Cd and MT-Cr associations in digestive gland and gills. Despite the high levels of Zn in specimens from B, association with Zn was not obtained. Due to the affinity of MT to various elements, it should not be excluded the possibility of Cd replacing Zn in Zn-MT. Kidney presented higher levels of Cd, Co, Ni and As than gills and gonads, and in the case of As surpassing the levels in digestive gland, but PCA showed no relation with MT. Likewise the MT levels in gonads had no correspondence to the metal concentration variation.     

Ethanol production from syngas by Clostridium strain P11 using corn steep liquor as a nutrient replacement to yeast extract

The feasibility of replacing yeast extract (YE) by corn steep liquor (CSL), a low cost nutrient source, for syngas fermentation to produce ethanol using Clostridium strain P11 was investigated. About 32% more ethanol (1.7 g L⁻¹) was produced with 20 g L⁻¹ CSL media in 250-mL bottle fermentations compared to media with 1 g L⁻¹ YE after 360 h. Maximum ethanol concentrations after 360 h of fermentation in a 7.5-L fermentor with 10 and 20 g L⁻¹ CSL media were 8.6 and 9.6 g L⁻¹, respectively, which represent 57% and 60% of the theoretical ethanol yields from CO. Only about 6.1 g L⁻¹ of ethanol was obtained in the medium with 1 g L⁻¹ YE after 360 h, which represents 53% of the theoretical ethanol yield from CO. The use of CSL also enhanced butanol production by sevenfold compared to YE in bottle fermentations. These results demonstrate that CSL can replace YE as the primary medium component and significantly enhance ethanol production by Clostridium strain P11.     

Ecophysiological responses of the mangrove Avicennia marina to trace metal contamination

Growth responses of Avicennia marina seedlings to contamination by different concentrations of two essential (Cu, Zn) and two non-essential (Pb, Hg) trace metals were studied under glasshouse conditions. We tested the hypothesis that soil retention and root ultrafiltration would exclude most of the trace metals, and that those that are absorbed and translocated to the shoots would interfere with plant performance and be excreted via leaf salt glands. One-month-old seedlings were subjected to Cu, Zn, Pb and Hg at concentrations of 0, 40, 80, 120 and 160 μg g⁻¹ sediment for 12 months in a randomized complete block design (n = 6). Photosynthesis was measured at the end of 12 months of trace metal exposure with a portable gas exchange system and chlorophyll fluorescence with a pulse-modulated fluorometer. After morphometric measurements, plants were harvested and analyzed for Cu, Zn, Pb and Hg by atomic absorption spectroscopy. Total dry biomass decreased with increasing trace metal concentration for all metals. In the 160 μg g⁻¹ Cu, Zn, Hg and Pb treatments, total biomass was significantly lower than the control value by 43%, 37%, 42% and 40%, respectively. Decreases in plant height and number of leaves followed trends similar to those for total biomass and ranged from 37% to 60%, compared to the controls. Decreases in chlorophyll content in the trace metal treatments ranged from 50% to 58% compared to the control. Carbon dioxide exchange, quantum yield of photosystem II (PSII), electron transport rate (ETR) through PSII and photosynthetic efficiency of PSII (F_v/F_m) were highest in the control treatment and decreased with increasing trace metal concentrations. Decreases in CO₂ exchange in the 160 μg g⁻¹ treatments for all trace metals ranged from 50% to 60%. Concentrations of all trace metals in plant organs increased with increasing metal concentrations and were higher in roots than in shoots, with concentrations of Cu and Zn being considerably higher than those of Hg and Pb. Qualitative elemental analyses and X-ray mapping of crystalline deposits over the glands at the leaf surfaces indicated that Cu and Zn were excreted from the salt glands, while Hg and Pb were absent, at least being below the limits of detection. These results demonstrate that growth processes are sensitive to trace metals and therefore can be considered as a cost of metal tolerance, but salt glands of this mangrove species do contribute eliminating at least part of physiologically essential trace metals if taken up in excess.     

Optimization, purification, characterization and antioxidant activity of an extracellular polysaccharide produced by Paenibacillus polymyxa SQR-21

The optimization, purification and characterization of an extracellular polysaccharide (EPS) from a bacterium Paenibacillus polymyxa SQR-21 (SQR-21) were investigated. The results showed that SQR-21 produced one kind of EPS having molecular weight of 8.96 × 10⁵ Da. The EPS was comprised of mannose, galactose and glucose in a ratio of 1.23:1.14:1. The ratio of monosaccharides and glucuronic acid was 7.5:1. The preferable culture conditions for EPS production were pH 6.5, temperature 30 °C for 96 h with yeast extract and galactose as best N and C sources, respectively. The maximum EPS production (3.44 g L⁻¹) was achieved with galactose 48.5 g L⁻¹, Fe³⁺ 242 μM and Ca²⁺ 441 μM. In addition, the EPS showed good superoxide scavenging, flocculating and metal chelating activities while moderate inhibition of lipid peroxidation and reducing activities were determined. These results showed the great potential of EPS produced by SQR-21 to be used in industry in place of synthetic compounds.     

Inter-population variability of leaf morpho-anatomical and terpenoid patterns of Pistacia atlantica Desf. ssp. atlantica growing along an aridity gradient in Algeria

Three Algerian populations of female Pistacia atlantica shrubs were investigated in order to check whether their terpenoid contents and morpho-anatomical parameters may characterize the infraspecific variability. The populations were sampled along a gradient of increasing aridity from the Atlas mountains into the northwestern Central Sahara.As evidenced by Scanning Electron Microscopy, tufted hairs could be found only on seedling leaves from the low aridity site as a population-specific trait preserved also in culture. Under common garden cultivation seedlings of the high aridity site showed a three times higher density of glandular trichomes compared to the low aridity site. Increased aridity resulted also in reduction of leaf sizes while their thickness increased. Palisade parenchyma thickness also increases with aridity, being the best variable that discriminates the three populations of P. atlantica.Analysis of terpenoids from the leaves carried out by GC-MS reveals the presence of 65 compounds. The major compounds identified were spathulenol (23 μg g⁻¹ dw), α-pinene (10 μg g⁻¹ dw), verbenone (7 μg g⁻¹ dw) and β-pinene (6 μg g⁻¹ dw) in leaves from the low aridity site; spathulenol (73 μg g⁻¹ dw), α-pinene (25 μg g⁻¹ dw), β-pinene (18 μg g⁻¹ dw) and γ-amorphene (16 μg g⁻¹ dw) in those from medium aridity and spathulenol (114 μg g⁻¹ dw), α-pinene (49 μg g⁻¹ dw), germacrene D (29 μg g⁻¹ dw) and camphene (23 μg g⁻¹ dw) in leaves from the high aridity site. Terpene concentrations increased with the degree of aridity: the highest mean concentration of monoterpenes (136 μg g⁻¹ dw), sesquiterpenes (290 μg g⁻¹ dw) and total terpenes (427 μg g⁻¹ dw) were observed in the highest arid site and are, respectively, 3-, 5- and 4-fold higher compared to the lower arid site. Spathulenol and α-pinene can be taken as chemical markers of aridity. Drought discriminating compounds in low, but detectable concentrations are δ-cadinene and β-copaene. The functional roles of the terpenoids found in P. atlantica leaves and principles of their biosynthesis are discussed with emphasis on the mechanisms of plant resistance to drought conditions.     

Sorgoleone,a sorghum root exudate: Algicidal activity and acute toxicity to the ricefish Oryzias latipes

The discovery of natural and natural-based compounds has resulted in its application as an alternative to synthetic algicides to control harmful algae in aquatic systems. Of the many natural-product-based algicides, sorgoleone, a natural plant product from Sorghum bicolor root exudates has been investigated for its controlling effect on different algal species and its acute fish toxicity. Growth of the blue green algal species Microcystis aeruginosa Kützing was completely inhibited by the crude methanol extract of sorghum root at 20 μg mL⁻¹. The most noticeable inhibition was observed in the bioassay of n-hexane soluble extract, where 98% growth inhibition occurred in M. aeruginosa at the concentration of 1.25 μg mL⁻¹. Sorgoleone very effectively controlled blue green algae inhibiting 97% of M. aeruginosa at 0.5 μg mL⁻¹ and 99% of Anabaena affinis Lemmermann at 4 μg mL⁻¹. In contrast, inhibition of the green algae species Chlorella vulgaris Beijerinck and Scenedensmus spp. at 16 μg mL⁻¹ sorgoleone was 87 and 68%, respectively. There were no mortalities or adverse effects observed in any of the fish exposed to water control, solvent control, and a nominal concentration of 1 μg mL⁻¹ during the test period. The no observed effect concentration (NOEC) value was 1.5 μg mL⁻¹ for the tested fish (O. latipes). Sorgoleone can be considered as an effective and an ecologically and environmentally sustainable approach to controlling harmful algae.     

Synthesis and characterization of a molecularly imprinted polymer and its application as SPE enrichment sorbent for determination of trace methimazole in pig samples using HPLC-UV

A novel molecularly imprinted polymer that could be applied as enrichment sorbent was prepared using methimazole (MMZ) as the template molecule, methacrylic acid as functional monomer, ethylene glycol dimethacrylate as cross-linker. Though evaluated by static, kinetic and competitive adsorption tests, the polymer exhibited high adsorption capacity, fast kinetics and good selective ability. A method for determination of trace MMZ was developed using this polymer as enrichment sorbent coupled with high performance liquid chromatography focusing on complex biological matrices. Under the optimum experimental conditions, the MMZ standard is linear within the concentration range studied, that is, from 0.5 μg L⁻¹ to 150 μg L⁻¹ (r² = 0.9941). Lower limits of detection (LOD, at S/N = 3) and quantification (LOQ, at S/N = 10) in pig samples were 0.63 μg kg⁻¹ and 2.10 μg kg⁻¹ for kidney, 0.51 μg kg⁻¹ and 1.70 μg kg⁻¹ for liver, 0.56 μg kg⁻¹ and 1.86 μg kg⁻¹ for muscle, respectively. Recoveries and relative standard deviation (RSD, n = 9) values for precision in the developed method were from 71.14% to 88.41% and from 2.53% to 6.18%.     

Techno-economic implications of improved high gravity corn mash fermentation

The performance of Saccharomyces cerevisiae MBG3964, a strain able to tolerate >18% v/v ethanol, was compared to leading industrial ethanol strain, Fermentis Ethanol Red, under high gravity corn mash fermentation conditions. Compared to the industrial ethanol strain, MBG3964 gave increased alcohol yield (140 g L⁻¹ vs. 126 g L⁻¹), lower residual sugar (4 g L⁻¹ vs. 32 g L⁻¹), and lower glycerol (11 g L⁻¹ vs. 12 g L⁻¹). After 72 h fermentation, MBG3964 showed about 40% viability, whereas the control yeast was only about 3% viable. Based on modelling, the higher ethanol tolerant yeast could increase the profitability of a corn-ethanol plant and help it remain viable through higher production, lower unit heating requirements and extra throughput. A typical 50 M gal y⁻¹ dry mill ethanol plant that sells dried distiller’s grain could potentially increase its profit by nearly $US3.4 M y⁻¹ due solely to the extra yield, and potentially another $US4.1 M y⁻¹ if extra throughput is possible.     

Alkyl-methylimidazolium ionic liquids affect the growth and fermentative metabolism of Clostridium sp

In this study, the effect of ionic liquids, 1-ethyl-3-methylimidazolium acetate [EMIM][Ac], 1-ethyl-3-methylimidazolium diethylphosphate [EMIM][DEP], and 1-methyl-3-methylimidazolium dimethylphosphate [MMIM][DMP] on the growth and glucose fermentation of Clostridium sp. was investigated. Among the three ionic liquids tested, [MMIM][DMP] was found to be least toxic. Growth of Clostridium sp. was not inhibited up to 2.5, 4 and 4 g L⁻¹ of [EMIM][Ac], [EMIM][DEP] and [MMIM][DMP], respectively. [EMIM][Ac] at <2.5 g L⁻¹, showed hormetic effect and stimulated the growth and fermentation by modulating medium pH. Total organic acid production increased in the presence of 2.5 and 2 g L⁻¹ of [EMIM][Ac] and [MMIM][DMP]. Ionic liquids had no significant influence on alcohol production at <2.5 g L⁻¹. Total gas production was affected by ILs at ?2.5 g L⁻¹ and varied with type of methylimidazolium IL. Overall, the results show that the growth and fermentative metabolism of Clostridium sp. is not impacted by ILs at concentrations below 2.5 g L⁻¹.     

Effect of lignocellulosic inhibitory compounds on growth and ethanol fermentation of newly-isolated thermotolerant Issatchenkia orientalis

A newly isolated thermotolerant ethanologenic yeast strain, Issatchenkia orientalis IPE 100, was able to produce ethanol with a theoretical yield of 85% per g of glucose at 42 °C. Ethanol production was inhibited by furfural, hydroxymethylfurfural and vanillin concentrations above 5.56 g L⁻¹, 7.81 g L⁻¹, and 3.17 g L⁻¹, respectively, but the strain was able to produce ethanol from enzymatically hydrolyzed steam-exploded cornstalk with 93.8% of theoretical yield and 0.91 g L⁻¹ h⁻¹ of productivity at 42 °C. Therefore, I. orientalis IPE 100 is a potential candidate for commercial lignocelluloses-to-ethanol production.     

Combined effects of temperature and cadmium exposure on haemocyte apoptosis and cadmium accumulation in the eastern oyster Crassostrea virginica (Gmelin)

Combined effects of acclimation temperature (12, 20 and 28 °C) and exposure to a toxic metal cadmium (Cd, 50 μg L⁻¹) on haemolymph parameters related to immune defense and metal transport were studied in a model marine bivalve, Crassostrea virginica. Acclimation to elevated temperatures resulted in higher plasma protein concentrations and increased Cd levels in oyster haemolymph plasma and haemocytes. Cd accumulation in haemocytes was linear over the 45 days of Cd exposure and accumulation rates were 0.10, 0.53 and 0.56 μg Cd g⁻¹ dry mass at 12, 20 and 28 °C, respectively. Percentage of blood Cd burden associated with haemocytes increased with increasing temperatures from 13–20% at 12 °C to 26–47% at 20 and 28 °C suggesting a higher role for cellular Cd transport at elevated temperatures. Cd levels in gills and hepatopancreas were positively correlated with Cd concentration in haemocytes, but accumulation rates were considerably faster, so that after 45 days of exposure Cd levels in gills and hepatopancreas were >10–20 times higher than in haemocytes. As a result of slow Cd accumulation possibly reflecting fast haemocyte turnover rates and/or exocytosis of Cd-containing granules, haemocytes in Cd-exposed oysters did not reach threshold Cd burdens required to trigger apoptosis. This suggests that haemocyte viability is not likely to contribute to immunosuppression in the environmentally relevant Cd range. In contrast, elevated temperature (28 °C) resulted in a significant increase in the percentage of apoptotic haemocytes compared to 12 or 20 °C supporting the notion that 28 °C is physiologically stressful for C. virginica. Overall, our study demonstrates strong effects of environmental temperature on haemocyte viability and other important blood parameters such as plasma protein content and metal transport capability which may mask potential Cd effects at environmentally relevant exposure levels.