Macro and micro-elements concentrations in Calligonum comosum wild grazing plant through its growth period

In this study, the change in the content of the macro and micro elements in the growing wild grazing plant of Calligonum comosum was tracked at the Research and Training Station of King Faisal University in Al-Hassa Governorate, Kingdom of Saudi Arabia. Mineral elements were estimated in aerial parts (plant as a whole, leaves and stem) from January-April 2020. The results showed that the concentration of nitrogen, phosphorus and potassium in the plant as a whole plant > leaves > roots, while the concentrations of calcium, magnesium, manganese, zinc and copper elements in the leaves was higher than other parts whereas the concentrations of these elements of whole plant were higher than the concentrations in roots. The results showed that the plant contents of nitrogen, potassium and zinc were the highest in March, while the concentrations of phosphorus, calcium, iron and copper were in February. The concentrations of magnesium, manganese and copper was the highest in January and April respectively. The values ​​of nitrogen, phosphorous, potassium, calcium, magnesium, iron, manganese, zinc and copper ranged from 11.1 to 18.4 g kg⁻¹, 4.17–2.33 g kg⁻¹, 13.73–18.97 g kg⁻¹, 24.50–28.90 g kg⁻¹, 10.40–12.30 gkg⁻¹, 1500–1677 mg kg⁻¹, 45.45–49.29 mg kg⁻¹, 70.70–177.23 mg kg⁻¹, 16.78–73.46 mg kg⁻¹, respectively. Furthermore, the results exhibited that the lowest values of the elements appeared in the plant roots in April. As well as, the distribution of the elements followed the normal life curve from January to April. Besides that, the evaluated elements satisfy the needs of the grazing animals' life in which this type of plant grows.     

Melatonin influence on in vitro callus induction and phenolic compound production in sweet basil (Ocimum basilicum L.)

The aim of the present study was to evaluate melatonin effects on the callus induction and phenolic compound production of Ocimum basilicum L. (sweet basil). Calluses, derived from leaf explants, were grown on Murashige and Skoog (MS) medium supplemented with 0, 100, or 200 μM melatonin, and subsequently extracted for determination of their phenolic contents. Melatonin decreased the callus induction in both concentrations. Based on the phytochemical analysis, the highest total phenolic acid contents (784.6 μg g⁻¹ and 335.2 μg g⁻¹, respectively) were recorded in calluses grown in 100 and 200 μM melatonin-supplemented medium, compared with the calluses induced with MS alone (192.0 μg g⁻¹). Among the five phenolic acids confirmed in the callus samples, rosmarinic acid was the major constituent. The amount of rosmarinic acid increased significantly in callus grown on 100 μM melatonin medium by nearly 5-fold (754.2 μg g⁻¹), compared with the control group callus. Major volatiles in basil calluses were represented by 3-methylbutanal, benzaldehyde, 1,8-cineole, 2-nonenal, eugenol, and methyl eugenol, and these were in the ranges of 4 to 14%, 24 to 50%, 2 to 3%, 0 to 0.55%, and 2 to 17% (in relative percentages), respectively. The qualitative and quantitative analyses of these substances found in calluses formed on melatonin-supplemented or melatonin-free medium were evaluated separately.

     

Bioproduction of phenylethanoid glycosides by plant cell culture of Scrophularia striata Boiss.: from shake-flasks to bioreactor

Phenylethanoid glycosides (PeG) are a class of polyphenols found in some plants that have pharmaceutical effects as anti-inflammatories and anti-oxidants. The presence of PeG (acteoside) in the aerial parts of Scrophularia striata Boiss. has been demonstrated. Considerable progress has been made using plant cell cultures to stimulate formation and accumulation of secondary metabolites. The present study optimized phenylethanoid production from shake flasks to bioreactor using a cell culture of S. striata. The optimal conditions for production of cell biomass by scale-up to a bioreactor were determined to be a pH of 4.8, air flow rate of 0.5–1.5 l min⁻¹, and mixing speed of 110–170 rpm at 25 ± 1 °C in darkness. Growth parameters and PeG production were measured and compared with the results from the shake flasks. The results showed that cell biomass was high in the bioreactor (15.64 g l⁻¹ DW) and in the shake flasks (14.16 g l⁻¹ DW). The acteoside content in the bioreactor was 1404.20 μg g⁻¹ DW, which is threefold higher than in the shake flasks (459.71 μg g⁻¹ DW). The echinacoside concentration in the bioreactor was 1449.39 μg g⁻¹, 1.36-fold lower than in the shake flasks (1973.03 μg g⁻¹ DW). This study established an efficient way for production of acteoside, the major PeG, in a bioreactor.

     

Characteristics of simultaneous organic and nutrient removal in a pilot-scale vertical submerged membrane bioreactor (VSMBR) treating municipal wastewater at various temperatures

A pilot-scale vertical submerged membrane bioreactor (VSMBR) with anoxic and oxic zones in one reactor was operated in an attempt to reduce the problems concerning effective removal of organic matter and nutrients from municipal wastewater. Source water with total chemical oxygen demand (TCOD)/total nitrogen (TN) ratio of 5.5 was treated at various temperatures (13–25 °C) over an interval of about 1 year. As a result, total suspended solid (TSS) and TCOD were removed by 100% and higher than 98%, respectively. Moreover, the average removal efficiencies of TN and total phosphorus (TP) were found to be 74% and 78% at 8 h-hydraulic retention time (HRT) and 60-days sludge retention time (SRT). Under these conditions, the specific removal rates (SRR) of TN and TP were found to be 0.093 kg N m⁻³ day⁻¹ and 0.008 kg P m⁻³ day⁻¹, and the daily production of excess sludge (DPES), 0.058 kg TSS day⁻¹.     

Smoke-saturated Water and Karrikinolide Modulate Germination,Growth, Photosynthesis and Nutritional Values of Carrot (Daucus carota L.)

Plant-derived smoke is a positive regulator of seed germination and growth with regard to many plant species. Of the several compounds present in plant-derived smoke, karrikinolide or KAR₁ (3-methyl-2H-furo[2,3-c]pyran-2-one) is considered to be the major active growth-promoting compound. To test the efficacy of smoke-saturated water (SSW) and KAR₁ on carrot (Daucus carota L.), two separate pot experiments were simultaneously conducted in the same environmental conditions. SSW and KAR₁ treatments were applied to the plants in the form of aqueous solutions of variable concentrations. Prior to sowing, seeds were soaked in the solutions of SSW (25.8 µg L⁻¹_, 51.6 µg L⁻¹,103.2 µg L⁻¹ and 258.0 µg L⁻¹) and KAR₁ (0.015 µg L⁻¹, 0.150 µg L⁻¹, 1.501 µg L⁻¹ and 15.013 µg L⁻¹). Percent seed germination, vegetative growth, photosynthesis and nutritional values were the major parameters through which the plant response to the applied treatments was investigated. The results obtained indicated a significant improvement in all the plant attributes studied. In general, SSW (51.6 µg L⁻¹) and KAR₁ (1.501 µg L⁻¹) proved optimum treatments for most the parameters. As compared to the control, 51.6 µg L⁻¹ of SSW and 1.501 µg L⁻¹ of KAR₁ increased the percent seed germination by 58.0% and 54.4%, respectively. Over the control, the values of plant height and net photosynthetic rate were enhanced by 33.9% and 40.9%, respectively, due to 51.6 µg L⁻¹ of SSW, while the values of these parameters were increased by 25.2% and 34.0%, respectively, due to 1.501 µg L⁻¹ of KAR₁. In comparison with the control, treatment 51.6 µg L⁻¹ of SSW increased the contents of β-carotene and ascorbic acid by 32.7% and 37.9%, respectively, while the treatment 1.501 µg L⁻¹ M of KAR₁ enhanced these contents by 42.0% and 48.4%, respectively. This study provides an insight into an affordable and feasible method of crop improvement.

     

Micropropagation,berberine content and antitumor activity of Jeffersonia dubia (Maxim.) Benth et Hook

An efficient micropropagation protocol was developed for Jeffersonia dubia using sucker explants. High frequency of multiple shoot formation was induced when the sucker explants were cultured on Chu’s (N6) medium with different concentrations of thidiazuron (TDZ) plus 0.54 µM α-naphthaleneacetic acid (NAA). The maximum frequency of shoot formation (96.2 %) was obtained on N6 medium with 2.27 µM TDZ plus 0.54 µM NAA. The highest mean number of shoots per explant (13.6) was obtained in temporary immersion system using an immersion frequency of 30 s every 30 min. The highest frequency of rooting (100 %), number of roots per shoot (5.8), and root length (6.3) was observed in half-strength N6 medium supplemented with 2.69 µM NAA. The regenerated plantlets (30 days old) were successfully acclimatized in the greenhouse with 98 % survival rate. The berberine content and cytotoxicity were higher in in vitro-developed calli and shoots than in leaves of field-grown plants. The greatest content of berberine was found in shoots (1381 μg g⁻¹) followed by calli (1092 μg g⁻¹) and leaves of field-grown plants (92 μg g⁻¹). At 1000 μg mL⁻¹ concentration, growth inhibition rate of berberine, callus, shoot, and leaf (in vivo) extracts were 68.4, 57.1, 54.2, and 17.7 %, respectively.

     

Yangyin Tongnao granules enhance neurogenesis in the peri-infarct area and upregulate brain-derived neurotrophic factor and vascular endothelial growth factor after focal cerebral ischemic infarction in rats

Yangyin Tongnao granules (YYTNG) have been extensively applied in the treatment of brain injury, mainly due to its antioxidant effects, inhibition of apoptosis, and enhancement of blood circulation. To analyze the effect of YYTNG on the recovery of neurological function and neurogenesis in the peri-infarct area after cerebral ischemic infarction in rats and to elucidate its role in the neuroprotective mechanism of stroke, Sprague–Dawley (SD) rats were subjected to middle cerebral artery occlusion (MCAO) for 90 min followed by reperfusion. Rats were randomly divided into five groups: sham, MCAO, and YYTNG-treated rats given doses of 0.83, 1.65, or 3.3 g kg^?1 day^?1. The YYTNG-treated groups (1.65 and 3.3 g kg^?1 day^?1) showed higher neurological scores and a lower infarct volume than the MCAO group on day 3 after MCAO. Furthermore, the YYTNG-treated groups (0.83, 1.65, and 3.3 g kg^?1 day^?1) showed higher neurological scores on day 7 after MCAO. The number of BrdU⁺/nestin⁺, BrdU⁺/NeuN⁺, and BrdU⁺/GFAP⁺ cells in the peri-infarct area 7 days after MCAO was significantly increased in the YYTNG-treated groups in a dose-dependent manner. The protein expression levels of brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF) were significantly higher in all three YYTNG-treated groups than in the MCAO group. Based on these results, administration of YYTNG post ischemia could ameliorate neurological function deficits in rats with MCAO. The therapeutic effect of YYTNG may be due to the promotion of neurogenesis in the peri-infarct area and the upregulation of neuroprotective factors BDNF and VEGF in MCAO rats.

     

In vitro assays on the susceptibility of four species of nematophagous fungi to anthelmintics and chemical fungicides/antifungal drug

Using nematophagous fungi for the biological control of animal parasitic nematodes will become one of the most promising strategies in the search for alternative chemical drugs. The purpose of this study was to check the in vitro activity of four anthelmintics, four chemical fungicides and two antifungal drugs on the spore germination of nematophagous fungi: Duddingtonia flagrans (SF170), Arthrobotrys oligospora (447), Arthrobotrys superba (435) and Arthrobotrys sp. (PS011). A modified 24-well cell culture plate assay was conducted to evaluate the susceptibility of nematophagous fungi against drugs tested by calculating the effective middle concentrations (EC₅₀) of each tested drug to inhibit the germination of fungal spores. EC₅₀ ranged between 0·7 and 47·2 μg ml⁻¹ for fenbendazole, thiabendazole and ivermectin, except levamisole (546·5–4057·8 μg ml⁻¹). EC₅₀ of tested fungicides was 0·6–2·3 μg ml⁻¹ for carbendazim, 55·9–247·4 μg ml⁻¹ for metalaxyl, 24·4–45·2 μg ml⁻¹ for difenoconazole, and 555·9–1438·3 μg ml⁻¹ for pentachloronitrobenzene (PCNB). EC₅₀ of two antifungal drugs was 0·03–3·4 μg ml⁻¹ for amphotericin B and 0·3–10·9 μg ml⁻¹ for ketoconazole. The results showed that 10 tested drugs, except for levamisole and PCNB, had in vitro inhibitory effects on nematophagous fungi. The chlamydospores of D. flagrans had the highest sensitivity to nine tested drugs, except for ketoconazole.     

Escape protein supplementation of growing steers grazing stargrass

A grazing trial utilizing 35 individually supplemented growing steers (211±42 kg initial body weight (BW)) was conducted to study the effect of supplemental escape protein on the performance of steers grazing on stargrass (Cynodon plectostachyus) during the dry season. N in supplements was 100%, 50%, or 0% natural protein (bloodmeal, coconut meal, and soybean meal), and 0%, 50% or 100% urea. All steers received 2 kg of supplement dry matter (DM) (2.2% N) daily during the 90 days of the experiment. Steers fed the urea supplement had the lowest ADG (0.97 kg day⁻¹). There was a linear (P<0.05) response in ADG to the natural protein level (50 and 100%) in supplements containing bloodmeal (1.11 and 1.21 kg day⁻¹) and coconut meal (1.05 and 1.21 kg day⁻¹), but no response was observed with soybean meal (1.01 and 1.0 kg day⁻¹). Forage intake was not affected by supplementation. As a result of the growth response observed for supplements containing bloodmeal and coconut meal above the urea-based and soybean meal supplements, it was concluded that growing ruminants grazing stargrass in the dry season were deficient in escape protein. ©1997 Elsevier Science B.V.     

Estimated feeding rates and energy requirements of gentoo penguins,Pygoscelis papua,at Macquarie Island

Summary Water and sodium turnovers of 6–7 week old gentoo penguin chicks and breeding adults were measured using isotopically labelled water and sodium. Influx rates for chicks averaged 188 ml·kg^-1·day^-1 and 13.9 mmol·kg^-1·day^-1 for water and sodium, respectively. Chicks consumed an estimated 228 g·kg^-1·day^-1 fresh food or 886 kJ kg^-1 day. These values correspond to 761 g·day^-1 or 2945 kJ·day^-1 for a gentoo chick mid-way through the growth period. Flux rates for adults attending chicks ranged from 199 to 428 ml·kg^-1·day^-1 for water and from 15 to 36 mmol·kg^-1·ay^-1 for sodium.     

The Interactive Effect of Selenium and Farmyard Manure on Soil Microbial Activities,Yield and Selenium Accumulation by Wheat (Triticum aestivum L.) Grains

This study assessed the interactive effect of selenium (Se) and farmyard manure (FYM) on soil microbial activities, growth, yield, and Se accumulation by wheat grains. Preliminarily, the effect of Se (0–250 µg kg^?1 soil) and FYM (0–12.5 g kg^?1 soil) was assessed on soil microflora. Selenium exhibited an adverse impact on soil microflora; respiration was decreased at?≥?10 µg kg^?1 soil while dehydrogenase and urease activities were decreased at?≥?125 µg kg^?1 soil. At 250 µg Se kg^?1 soil, respiration, dehydrogenase and urease activities were decreased by 81, 40 and 35%, respectively, on unamended soil, and by 9, 47 and 22%, respectively, on FYM-amended soil. The subsequent plant experiments were conducted with same Se and FYM rates; one was harvested 42 days after sowing and other at crop maturity. The application of 125 µg Se kg^?1 and 12.5 g FYM kg^?1 soil improved seedling biomass by 12.6 and 22%, respectively, while their combined use lacked synergistic effect. Similarly, at maturity Se and FYM increased grain yield while their combined effect was not synergistic. The Se-induced suppression in microbial activities was not related to yield which was improved (11% at the highest rate in unamended soil) by Se application. Selenium application increased grain Se content in a rate-dependent manner, it increased from 0 to 1025 µg kg^?1 by applying 250 µg Se kg^?1 soil. Moreover, FYM application decreased Se accumulation in grains. It is concluded that FYM application increased soil microbial activities and yield but reduced grain Se accumulation in wheat on Se-applied soil.

     

Combined and Singular Effects of Dietary PrimaLac® and Potassium Diformate (KDF) on Growth Performance and Some Physiological Parameters of Rainbow Trout (Oncorhynchus mykiss)

The present study was conducted to assess the effects of combined and singular dietary administration of PrimaLac® and potassium diformate (KDF) on growth performance, feed utilization, digestive enzymes activity, and some physiological parameters of rainbow trout (Oncorhynchus mykiss) juvenile. Three hundred sixty rainbow trout juveniles (25 ± 1.8 g) were randomly stocked in 300-L tanks (30 fish/tank), and fed three times daily on a basal diet (control), diets incorporated with 12 g kg⁻¹ KDF (FT₁), 1.5 g kg⁻¹ PrimaLac® (FT₂), and combination of 1.5 g kg⁻¹ probiotic and 12 g kg⁻¹ KDF (FT₃) in triplicates, for 8 weeks. At the end of feeding trial, growth performance, body composition, digestive enzymes, liver enzymes, and biochemical parameters were measured. Our results revealed that combined administration of PrimaLac® and KDF (FT₃) exhibited significantly higher weight gain and specific growth rate (SGR) compared to other groups (P < 0.05). Glucose and cortisol levels showed no significant differences between fish fed different test diets (P > 0.05). The highest lipase, protease and amylase activity were observed in group of fish fed FT₃ followed by FT₂ and FT₁. Besides, the diets FT₂ and FT₃ led to significantly lower of ALP, ALT, and AST compared to control group. The present results indicated that combined administration of PrimaLac® and KDF can be considered as a beneficial feed additive and growth promotor for O. mykiss juvenile.

     

Effects of mixing Neolamarckia cadamba leaves on fermentation quality,microbial community of high moisture alfalfa and stylo silage

Neolamarckia cadamba is not only a fodder of high nutritional value, but also a source of natural antimicrobial agent. The silage quality of high moisture alfalfa and stylo with or without N. cadamba leaves (NCL) was investigated, and microbial community after ensiling was analysed. Results showed that the silage samples with NCL have lower pH (4.32 versus 4.88, 4.26 versus 4.71 in alfalfa and stylo silage, respectively), ammonia-N content (67.5 versus 146, 42.2 versus 95.1 g kg⁻¹ total N) and higher lactic acid (13.3 versus 10.4, 17.3 versus 13.6 g kg⁻¹ dry matter), true protein N (592 versus 287, 815 versus 589 g kg⁻¹ total N). The addition of NCL also influenced the bacterial community distribution. The relative abundance of Clostridium and Enterobacter decreased, whereas Lactobacillus abundance increased when NCL was added. In conclusion, NCL could inhibit undesirable microorganisms in high moisture alfalfa and stylo silage. Mixing with NCL could be a feasible way to improve the quality of silage.     

The effects of arsenic and induced-phytoextraction methods on photosynthesis in Pteris species with different arsenic-accumulating abilities

Arsenic (As) accumulation and photosynthesis occur simultaneously in plants under As exposure. We investigated the effects of As and induced-phytoextraction methods on photosynthesis in two As hyperaccumulators (Pteris vittata and Pteris cretica var. nervosa) and two non-hyperaccumulators (Pteris semipinnata and Pteris ensiformis) under soil culture conditions. Chlorophyll fluorescence parameters (the maximum [F_v/F_m] and actual quantum efficiency [F_PSII]) and the activities of three photosynthetic enzymes (ATPase, ribulose-1, 5-bisphosphate carboxylase [RuBPC] and glyceraldehyde-3-phosphate dehydrogenase [GAPDH]) were measured. Arsenic accumulation and photosynthetic behaviours in response to enhanced-phytoextraction methods (trans-1, 2-cyclobexylenedinitrilotetraacetic acid [CDTA] and phosphorous [P] addition and soil pH adjustment) of P. cretica and P. semipinnata were monitored and compared under conditions of 100 mg As kg⁻¹. Significant decreases in the F_v/F_m (19.9%) and F_PSII (36.1%) were observed in P. vittata when exposed to 100 mg As kg⁻¹ in comparison to the control (0 mg As kg⁻¹). Compared to the control (0 mg As kg⁻¹), the activities of GAPDH increased by 0.5% in P. cretica var. nervosa and decreased by only 8.3% in P. vittata even when both of them were treated with 200 mg As kg⁻¹, whereas a significant decrease, 56.1% and 51.7%, of this enzyme was observed in P. semipinnata and P. ensiformis, respectively, when exposed to 50 mg As kg⁻¹. Compared to the control (0 mg CDTA kg⁻¹ or 0 mg P kg⁻¹), the activities of ATPase increased by 53.7% and 82.7% in P. cretica when exposed to 0.5 g CDTA kg⁻¹ and 50 mg P kg⁻¹, respectively, and an increase of up to 175% was also observed in P. semipinnata when exposed to 600 mg P kg⁻¹. The activities of GAPDH increased by 68.9% and 90.7% in P. cretica when exposed to 2 g CDTA kg⁻¹ and 600 mg P kg⁻¹, respectively, but a decrease of up to 60% was observed in P. semipinnata when exposed to 2 g CDTA kg⁻¹. The uptake of As in P. semipinnata increased by 80.9% and 73.3% when 1 g CDTA kg⁻¹ and 600 mg P kg⁻¹ were added, respectively, compared to the control (0 g CDTA kg⁻¹ or 0 mg P kg⁻¹). It was concluded that GAPDH played an important role in the photosynthesis of As hyperaccumulators under As treatments.     

Bioaccessibility and Risk Assessment of Cadmium from Uncooked Rice Using an In Vitro Digestion Model

Cadmium (Cd)-contaminated rice is one of the most important sources of cadmium exposure in the general population from some Asian countries. This study was conducted to assess cadmium exposure from uncooked rice in rural mining areas based on the bioaccessible fraction of cadmium using an in vitro digestion model. The biotoxic effects of cadmium in uncooked rice from mining areas were much higher than those in the control area, based not only on their higher total concentration (52.49 vs. 7.93 μg kg⁻¹), but also on their higher bioaccessibility (16.94% vs. 2.38%). In the mining areas, the bioaccessible fraction of cadmium in uncooked rice has a significant positive correlation with the total concentration of cadmium in rice and there was quarterly unsafe rice to the public in the mining areas. The results indicated that the in vitro digestion model could be a useful and economical tool for providing the solubilization or bioaccessibility of uncooked rice in the mining area. The results could be helpful in conducting future experiments of cooked rice in the vitro model.     

Direct emission of methane and nitrous oxide from switchgrass and corn stover: implications for large-scale biomass storage

Little is known about the contributions of biomass feedstock storage to the net greenhouse gas emissions from cellulosic biofuels. Direct emissions of methane and nitrous oxide during decomposition in storage may contribute substantially to the global warming potential of biofuels. In this study, laboratory-scale bales of switchgrass and corn stover were stored under a range of moisture (13.0–32.9%) and temperature (5–35 °C) conditions and monitored for O₂ consumption and CO₂, CH₄, and N₂O production over 8 weeks. Gas concentrations and emissions rates were highly variable within and between experimental groups. Stover bales produced higher CO₂ concentrations (P = 0.0002) and lower O₂ (P < 0.0001) during storage than switchgrass bales. Methane concentrations (1.8–2100 ppm) were inversely correlated with bale moisture (P < 0.05), with emissions rates ranging from 4.4–914.9 μg kg⁻¹ DM day⁻¹. Nitrous oxide concentrations ranged from 0 to 31 ppm, and emissions from switchgrass bales inversely correlated with temperature and moisture (P < 0.0001). Net global warming potential from each treatment (0–2.4 gCO₂e kg⁻¹ DM) suggests that direct emission of methane and nitrous oxide from aerobically stored feedstocks have a small effect on net global warming potential of cellulosic biofuels.     

Insights into collateral susceptibility and collateral resistance in Acinetobacter baumannii during antimicrobial adaptation

The susceptibility of Acinetobacter baumannii exposed to primary antibiotic can be either increased or decreased when exposed to secondary antibiotic. This study was designed to assess the relative fitness, collateral susceptibility and collateral resistance of polymyxin B- (PMB-) adapted A. baumannii to ciprofloxacin (CIP), meropenem (MER), PMB, tetracycline (TET) and tobramycin (TOB). Strains of wild-type A. baumannii KACC 12454 (AB^KACC), wild-type A. baumannii CCARM 12088 (AB^CCARM), PMB-adapted AB^KACC, PMB-adapted AB^CCARM, stabilized AB^KACC and stabilized AB^CCARM were used in this study. Compared to the wild-type AB^KACC, the MICs of PMB were increased from 2 to 128 μg ml⁻¹ against PMB-adapted AB^KACC, while MICs of CIP, MER, TET and TOB were decreased from 2 to 1 μg ml⁻¹, 16 to 1 μg ml⁻¹, 16 to 2 μg ml⁻¹ and 64 to 16 μg ml⁻¹, respectively. The PMB-adapted AB^CCARM was resistant to CIP (32 μg ml⁻¹) and PMB (64 μg ml⁻¹) compared to the wild-type AB^CCARM. The resistance of stabilized AB^KACC and AB^CCARM to all antibiotics was lost after antibiotic-free culture in the exception of CIP and TET. The susceptibilities of wild-type, PMB-adapted and stabilized AB^KACC and AB^CCARM to CIP, MER, PMB, TET and TOB were increased in the presence of β-lactamase and efflux pump inhibitors. The high levels of relative fitness were observed for stabilized AB^KACC, PMB-adapted AB^CCARM and stabilized AB^CCARM. The stabilized AB^KACC and PMB-adapted AB^CCARM were highly heteroresistance to PMB and TET, respectively. The PMB-adapted AB^KACC and AB^CCARM showed various antibiotic patterns, known as collateral susceptibility and collateral resistance. The results provide useful information for designing effective antibiotic regimens that can enhance the antibiotic activity against A. baumannii infections.     

Effect of different CO2 concentrations on biomass,pigment content,and lipid production of the marine diatom Thalassiosira pseudonana

The marine diatom Thalassiosira pseudonana grown under air (0.04% CO₂) and 1 and 5% CO₂ concentrations was evaluated to determine its potential for CO₂ mitigation coupled with biodiesel production. Results indicated that the diatom cultures grown at 1 and 5% CO₂ showed higher growth rates (1.14 and 1.29 div day⁻¹, respectively) and biomass productivities (44 and 48 mg_AFDWL⁻¹ day⁻¹) than air grown cultures (with 1.13 div day⁻¹ and 26 mg_AFDWL⁻¹ day⁻¹). The increase of CO₂ resulted in higher cell volume and pigment content per cell of T. pseudonana. Interestingly, lipid content doubled when air was enriched with 1–5% CO₂. Moreover, the analysis of the fatty acid composition of T. pseudonana revealed the predominance of monounsaturated acids (palmitoleic-16:1 and oleic-18:1) and a decrease of the saturated myristic acid-14:0 and polyunsaturated fatty acids under high CO₂ levels. These results suggested that T. pseudonana seems to be an ideal candidate for biodiesel production using flue gases.

     

Chara hispida beds as a sink of nitrogen: Evidence from growth,nitrogen uptake and decomposition

Chara hispida forms dense beds (0.78–0.95 kg DW m⁻²) in Colgada Lake. The ability of Chara meadows to act as a nitrogen source or sink was evaluated by the following methods: (1) investigating Chara growth, (2) nitrogen incorporation and decomposition laboratory experiments and (3) relating experimental results to field conditions. Sediment oospores were germinated in large aquaria and observed growth rates were 0.001 m day⁻¹ (shoot length) and 0.0002 g day⁻¹ (dry weight). Nitrogen uptake rates were determined by addition of K¹⁵NO₃ during two different periods of Chara growth and the rates were 1.21 and 3.86 μM g DW⁻¹ h⁻¹ when charophytes were 166 days old (not sexually mature) and 323 days old (sexually mature), respectively. After the uptake experiments, the same charophytes were allowed to decompose within two types of litter bags (3 mm-pore litter bags and entire, non-porous plastic litter bags). Decomposition rates of Ch. hispida were 0.016 and 0.009 day⁻¹ in perforated and non-perforated bags, respectively, and fit a negative exponential model. The nitrogen release rate, calculated as the disappearance of N content from Chara tissues, was 0.012 day⁻¹ and there were no statistically significant differences between the values from the two different bag types. The dissolved organic nitrogen concentrations in aquarium and non-perforated litter bags waters increased linearly with time due to the leaching of soluble compounds from Chara. The rate of N loss from Chara tissues, total nitrogen and dissolved organic nitrogen release rates and the decrease in initial dry weight rate were all lower than the daily rate of Chara N uptake. By extrapolating laboratory data to field situations, we determined that approximately 38% of the N taken up by charophytes in Colgada Lake during the growth period is retained. Given the high charophyte biomass in the lake, its ability to incorporate nitrogen, its low decomposition rate and its ability to over-winter, we conclude that Chara beds could be acting as nitrogen sinks in this ecosystem.     

Degradation of aflatoxin B1 during anaerobic digestion and its effect on process stability

The effect of aflatoxin B1 (AFB1) on an anaerobic digestion process (AD) was studied. Batch anaerobic digestion trials were performed with both non-contaminated AFB1 corn grain (Control A) and contaminated-AFB1 corn grain at different doses (AFB1 contents of 0.54, 66.2, and 110 μg kg⁻¹ wet weight). Both cumulative biogas production and the degradation rate of AFB1 were studied. Results indicated that no adverse effects on AD were detected during the processes which could be attributed to the presence of AFB1. AFB1 degradation ranged from 69% to 87% of the total initial AFB1 content.Anaerobic digestion trials using Completely Stirred Tank Reactors (CSTR) were also carried out, comparing the biogas production of a mix of contaminated corn grain plus pig slurry (AFB1 content of 7.2 μg kg⁻¹ wet weight) with a mix of non-contaminated corn grain plus pig slurry (Control B). No adverse effect of AFB1 on biogas production was detected. The CSTR trial resulted in an average degradation of AFB1 of 42%. The further storage of the digestate for 30 days resulted in an overall degradation (CSTR plus storage) of AFB1 of 61% of the starting content.