Sequestration of dietary alkaloids by the spongivorous marine mollusc Tylodina perversa

Specimens of the spongivorous Mediterranean opisthobranch Tylodina perversa that had been collected while feeding on Aplysina acerophoba were shown to sequester the brominated isoxazoline alkaloids of their prey. Alkaloids were stored in the hepatopancreas, mantle tissues, and egg masses in an organ-specific manner. Surprisingly, the known sponge alkaloid aerothionin which is found only in A. cavernicola but not in A. aerophoba was also among the metabolites identified in wild caught specimens of T. perversa as well as in opisthobranchs with a documented feeding history on A. aerophoba. Mollusc derived aerothionin is postulated to be derived from a previous feeding encounter with A. cavernicola as T. perversa was found to freely feed on both Aplysina sponges in aquarium bioassays. The possible ecological significance of alkaloid sequestration by T. perversa is still unknown.     

Wound-induced accumulations of condensed tannins in turtlegrass, Thalassia testudinum

Turtlegrass, Thalassia testudinum, produces high concentrations of proanthocyanidins (condensed tannins) which we hypothesized are induced by grazing, as a component of a general wound response. To test this we quantified condensed tannins in a variety of turtlegrass tissues following simulated fish grazing, grazing by the urchin Lytechinus variegatus, and treatment with the natural plant wound hormone jasmonic acid. We observed that simulated fish grazing triggered rapid induction of condensed tannins by an average of 10 mg tannin g⁻¹ dry mass (DM) after 5 days. Condensed tannin accumulations were correlated with a reduction of blade extension rates. Further, we observed that constitutive tannin levels in developing first-rank leaves were strongly correlated with the width of second-rank leaves on each shoot, with an increase of 7.7 mg tannin g⁻¹ tissue dry mass per millimeter blade width on average. We propose that wider source leaves provide additional resources for phenolic biosynthesis. There was no induction of tannins in leaves, meristematic or sheath tissues in response to grazing by the urchin L. variegatus, the presence of potential waterborne cues from nearby grazed plants, or to treatment with 5 mM jasmonic acid. However, urchin grazing did induce tannin production in root/rhizome tissues, where they accumulated to levels 3–4 times higher than in blades (up to 350 mg tannin g⁻¹ tissue dry mass). These results confirm the potential for rapid wound-induced condensed tannin accumulations in T. testudinum. The link between blade widths and the tannin content of new leaves indicates that leaf morphology may be a useful bioindicator for predicting herbivore and disease-resistance in the field.     

Cadmium biosorption on Spirulina platensis biomass

Dry biomass of Spirulina platensis re-hydrated for 48 h was employed as a biosorbent in tests of cadmium(II) removal from water. Various concentrations of biomass (from 1 to 4 g l⁻¹) and metal (from 100 to 800 mg l⁻¹) were tested. Low biomass levels (X_o  2 g l⁻¹) ensured metal removal up to 98% only at Cd₀= 100 and 200 mg l⁻¹, while X_o  2.0 g l⁻¹ were needed at Cd₀ = 400 mg l⁻¹ to achieve satisfactory results. Whereas X_o = 4.0 g l⁻¹ was effective to remove up to Cd₀ = 500 mg l⁻¹, a further increase in metal concentration (Cd₀ = 600 and 800 mg l⁻¹) led to progressive worsening of the system performance. At a given biomass levels, the kinetics of the process was better at low Cd²⁺ concentrations, while, raising the adsorbent level from 1.0 to 2.0 g l⁻¹ and then to 4.0 g l⁻¹, the rate constant of biosorption increased by about one order of magnitude in both cases and the adsorption capacity of the system progressively decreased from 357 to 149 mg g⁻¹.     

Transformation of Saussurea involucrata by Agrobacterium rhizogenes: Hairy root induction and syringin production

Agrobacterium rhizogenes-mediated genetic transformation of Saussurea involucrata was investigated. Four bacterial strains, A4, LBA 9402, R1000 and R1601 and three explant types, leaf blade, petiole and root, were examined. Over 100 hairy root lines were successfully established with strains R1601, R1000 and LBA9402, but none with A4. The highest transformation efficiency of 67% was achieved by using strain R1601 with root explants. One hairy root line isolated from this combination, HR1601-1, produced up to 43.5 ± 1.13 mg syringin g⁻¹ dw, which is about 50-fold higher than that in the wild type plants.Two other lines, HR1000-1 and HRLBA9402-1, isolated from R1000- and LBA9402-transformed roots, respectively, also displayed high capacity of syringin production, being 32.5 ± 3.08 and 39.7 ± 1.37 mg syringin g⁻¹ dw. These three lines were characterized in detail. Polymerase chain reaction analyses confirmed these root lines were of A. rhizogenes origin.     

Phenol inhibition of biological nutrient removal in a four-step sequencing batch reactor

Nutrient removal from synthetic wastewater was investigated using a four-step sequencing batch reactor (SBR) at different phenol (C₆H₅OH) concentrations in order to determine the inhibition effects of phenol on biological nutrient removal. The nutrient removal process consisted of anaerobic, oxic, anoxic, and oxic phases with hydraulic residence times (HRT) of 1 h/3 h/1 h/1 h and a settling phase of 3/4 h. Solids retention time (SRT) was kept constant at 10 days in all experiments. Initial phenol concentrations were varied between 0 and 600 mg l⁻¹ at seven different levels. The effects of phenol on COD, NH₄-N, and PO₄-P removals and effluent nutrient levels were investigated. Phenol was almost completely degraded up to 400 mg l⁻¹ phenol concentration resulting in almost negligible inhibition effects on COD, NH₄-N, and PO₄-P removals. Nutrient removals were adversely affected by phenol at concentrations above 400 mg l⁻¹. Above 95% COD, 90% NH₄-N and 65% PO₄-P removal was obtained for phenol concentrations below 400 mg l⁻¹. The sludge volume index (SVI) was almost constant around 45 ml g⁻¹ for phenol concentrations below 400 mg l⁻¹ but increased to 90 ml g⁻¹ at a phenol level of 600 mg l⁻¹.     

The response of an emergent sedge Bolboschoenus medianus to salinity and nutrients

The potential for nutrient load (30, 100 and 350 g N m⁻² per year) to alter plant performance under saline conditions (control, 4.5, 9 and 13 dS m⁻¹) was examined in the sedge Bolboschoenus medianus. Relative growth rates (RGR) across nutrient loadings ranged from 30.2 to 41.8 mg g⁻¹ per day in controls and were reduced to 20.9–28.5 mg g⁻¹ per day by salinities of 13 dS m⁻¹. Whilst higher nutrient loads generally increased RGR, the response was smaller at higher salinities. Responses to salinity and nutrient load were specific. Nutrient load increased the RGR via increases in the leaf area ratio (LAR). The LAR ranged from 1.9 to 2.1 m² kg⁻¹ across salinity treatments at 30 g N m⁻² per year, and increased to 2.5–2.8 m² kg⁻¹ at 350 g N m⁻² per year. Salinity reduced the RGR via a reduction in the net assimilation rate (NAR). The NAR in control plants ranged from 14.7 to 16 g m⁻² per day across nutrient loadings and decreased to 11–12 g m⁻² per day at 13 dS m⁻¹. Carbon isotope discrimination of leaves decreased by 2–3‰ in response to 13 dS m⁻¹ at the lower nutrient loadings. A prominent response of B. medianus to salinity was a change in biomass allocation from culms to tubers. In contrast, the response to nutrient load was characterised by a shift in biomass allocation from roots to leaves.     

Removal of lead (Pb(2+)) by the cyanobacterium Gloeocapsa sp

Pb²⁺ removal ability of the viable-freshwater cyanobacterium Gloeocapsa sp. was studied in batch experiments. Gloeocapsa sp. was cultured in the Medium 18 with pH adjusted to 3, 4, 5, 6 and 7. Growth was subsequently determined based on the increase of chlorophyll-a content. Gloeocapsa sp. was able to grow at all pH levels tested, except at pH 3. Removal of Pb²⁺ was then further studied under pH 4. The results showed that Pb²⁺ concentration in the range of 0–20 mg L⁻¹ was not inhibitory to Gloeocapsa sp. growth but reduced its Pb²⁺ removal efficiency (by 4.5% when Pb²⁺ concentration increased from 2.5 to 20 mg L⁻¹). Pb²⁺ removal characteristics followed the Langmuir adsorption isotherm with the maximum removal capacity (q_max) of 232.56 mg g⁻¹. Adsorption of Pb²⁺ by this cyanobacterium followed the second order rate reaction and intraparticle diffusion was likely the rate-determining step. The initial rate of Pb²⁺adsorption during intraparticle diffusion was slower under light than under dark conditions, indicating that light probably slowed down the initial rate of intraparticle diffusion through the repulsion effects on cell membrane.     

The dinoflagellate Alexandrium minutum in Cape Town harbour (South Africa): Bloom characteristics, phylogenetic analysis and toxin composition

A novel bloom of Alexandrium minutum occurred in an inner basin of the Cape Town harbour from November 2003 to February 2004. Cellular concentrations reached a maximum of 1.4 × 10⁸ cells l⁻¹ during the mid-December period with corresponding chlorophyll a concentrations of 243 mg m⁻³. Primary productivity measurements conducted during the latter part of the bloom revealed a maximum assimilation number of 11.17 mg C mg Chl a⁻¹ h⁻¹ during the middle of the day. Productivity during this post-peak period was sustained largely by the reduced nitrogen species NH₄ and urea (96%) as measured using ¹⁵N tracer techniques. The large subunit ribosomal DNA sequence of A. minutum isolates from Cape Town harbour was identical to conspecifics collected in Western Europe and in Australia. The composition of tetrahydropurine neurotoxins associated with paralytic shellfish poisoning (PSP) was limited to gonyautoxins (GTX1-GTX4). This profile combined with evidence of a low toxin cell quota (1.5 fmol GTX cell⁻¹) supports a close association of this taxon with other members of the A. minutum species complex, particularly from Europe. Toxin analysis from black mussels collected during this bloom indicated that the accumulated PSP toxins originated from A. minutum and not from Alexandrium catenella as is most often the case along the South African coast.     

Simultaneous production of anthocyanin and triterpenoids in suspension cultures of Perilla frutescens

When cultivated in Murashige & Skoog medium supplemented with 0.2 mg l⁻¹ 2,4-dichlorophenoxy acetic acid and 0.5 mg l⁻¹ 6-benzyladenine, Perilla frutescens cells in suspension culture grew rapidly reaching about 13.6 g dry wt l⁻¹ after 12 days. The cell line produced both anthocyanin 0.9 g l⁻¹ and triterpenoids: 16 mg l⁻¹ oleanolic acid (OA), 25 mg l⁻¹ ursolic acid (UA) and 14 mg l⁻¹ tormentic acid (TA). When P. frutescens cells of 7-day-old cultures were exposed to a yeast elicitor at 0.5–5% (v/v) for 7 days, it was found that anthocyanin content peaked at 10.2% of dry weight with yeast elicitor at 1% (v/v) whereas the maximum production of oleanolic acid and ursolic acid in cultures treated with 2% (v/v) yeast elicitor was 19 and 27 mg l⁻¹, a 46 and 24% increase over the control, respectively. This is the first report of simultaneous production of both anthocyanin and triterpenoids in a single culture system.     

Comparative aspects of the thermal biology of the short-tailed gerbil, Desmodillus auricularis, and the bushveld gerbil, Tatera leucogaster

1. 1. The response of oxygen consumption (VO₂), thermal conductance (C_d and C_min, body temperature (T_b), and evaporative water loss (EWL) of Tatera leucogaster and Desmodillus auricularis were measured over the range of ambient temperatures (T_a) from 5–35°C.

2. 2. Basal metabolic rate (BMR) of T. leucogaster was 0.841 ± 0.049 ml O₂ g⁻¹ h⁻¹ and lower than predicted, while that of D. auricularis was similar to the expected value (1.220 ± 0.058 ml O₂ g⁻¹ h⁻¹). D. auricularis had a high, narrow thermoneutral zone (TNZ) typical of nocturnal, xerophilic, burrowing rodents.

3. 3. D. auricularis and T. leucogaster regulated T_b over the range T_a = 5–35°C and kept EWL and dry thermal conductance at a minimum below the TNZ. However, the EWL of T. leucogaster increased rapidly above T_a = 30°C.

4. 4. After comparison with data from other species, it was concluded that there is an optimum size for xeric, nocturnal, burrowing rodents.

Metal accumulation by Halodule wrightii populations

Metal concentrations and population parameters of the seagrass Halodule wrightii were determined at three locations at Rio de Janeiro State, Brazil. The possible increase of metal availability in one of these areas, Sepetiba Bay, as a result of dredging of contaminated bottom sediments which ocurred, was evaluated by analyses of Al, Cd, Cr, Cu, Fe, Ni, Pb and Zn in root, rhizome and shoots. In addition, analyses were carried out in H. wrightii populations from non-contaminated areas located at northwestern (Cabo Frio) and southeastern (Angra do Reis) regions of Rio de Janeiro State. Concurrently, abundance and density data of the seagrass populations were obtained. It was found that concentration from Sepetiba Bay samples up to 1.6 ± 0.4 μg g⁻¹ of Cd, 12 ± 1.0 μg g⁻¹ of Cr, 27 ± 2.4 μg g⁻¹ of Pb, 291 ± 47 μg g⁻¹ of Mn, 128 ± 23 μg g⁻¹ of Zn were significantly higher than that from two other collection sites. An increase in Cd and Zn concentration was observed in H. wrightii from Sepetiba Bay indicating that metal mobilization from contaminated sediments through dredging activities were, at least in part, transferred to the biotic compartment via accumulation by the seagrass. The populations of seagrass within the region demonstrated quite substantial changes in biomass data but not in shoot or rhizome density during the study. Such changes in biomass are to be expected, as these dynamics are typical of the small, isolated monospecific populations of H. wrightii along the Rio de Janeiro coast.     

Bench-scale fermentation of Trichoderma viride on wastewater sludge: Rheology, lytic enzymes and biocontrol activity

Conidiation and lytic enzyme production by Trichoderma viride at different solids concentration of pre-treated municipal wastewater sludge was examined in a 15-L fermenter. The maximum conidia concentration (5.94 × 10⁷ CFU mL⁻¹ at 96 h) was obtained at 30 g L⁻¹ suspended solids. The maximum lytic enzyme activities were achieved around 12–30 h of fermentation. Bioassay against a fungal phytopathogen, Fusarium sp. showed maximum activity in the sample drawn around 96 h of fermentation at 30 g L⁻¹ suspended solids concentration. Entomotoxicity against spruce budworm larvae showed maximum value ≈17290 SBU μL⁻¹ at 30 g L⁻¹ suspended solids concentration at the end of fermentation (96 h). Plant bioassay showed dual action of T. viride, i.e., disease prevention and growth promotion. The rheological analyses of fermentation sludges showed the pseudoplastic behaviour. In order to maintain required dissolved oxygen concentration ≥30%, the agitation and aeration requirements significantly increased at 35 g L⁻¹ compared to 30 and 25 g L⁻¹. The oxygen uptake rate and volumetric oxygen mass transfer coefficient, k_La at 35 g L⁻¹ did not increase in comparison to 30 g L⁻¹ due to rheological complexity of the broth during fermentation. Thus, the successful fermentation operation of the biocontrol fungus T. viride is a rational indication of its potential for mass-scale production for agriculture and forest sector as a biocontrol agent.     

Biosorption of copper by marine algae Gelidium and algal composite material in a packed bed column

Marine algae Gelidium and algal composite material were investigated for the continuous removal of Cu(II) from aqueous solution in a packed bed column. The biosorption behaviour was studied during one sorption–desorption cycle of Cu(II) in the flow through column fed with 50 and 25 mg l⁻¹ of Cu(II) in aqueous solution, at pH 5.3, leading to a maximum uptake capacity of ≈13 and 3 mg g⁻¹, respectively, for algae Gelidium and composite material. The breakthrough time decreases as the inlet copper concentration increases, for the same flow rate. The pH of the effluent decreases over the breakthrough time of copper ions, which indicates that ion exchange is one of the mechanisms involved in the biosorption process. Temperature has little influence on the metal uptake capacity and the increase of the ionic strength reduces the sorption capacity, decreasing the breakthrough time. Desorption using 0.1 M HNO₃ solution was 100% effective. After two consecutive sorption–desorption cycles no changes in the uptake capacity of the composite material were observed. A mass transfer model including film and intraparticle resistances, and the equilibrium relationship, for adsorption and desorption, was successfully applied for the simulation of the biosorption column performance.     

Bioaccumulation of copper(II), lead(II) and chromium(VI) by growing Aspergillus niger

The effect of copper(II), lead(II) and chromium(VI) ions on the growth and bioaccumulation properties of Aspergillus niger was investigated as a function of initial pH and initial metal ion concentration. The optimum pH values for growth and metal ion accumulation were determined as 5.0, 4.5 and 3.5 for copper(II), lead(II) and chromium(VI) ions, respectively. Although all metal ion concentrations caused an inhibition effect on the growth of A. niger, it was capable of removing of copper(II) and lead(II) with a maximum specific uptake capacity of 15.6 and 34.4 mg g⁻¹ at 100 mg dm⁻³ initial copper(II) and lead(II) concentration, respectively. Growth of A. niger was highly effected by chromium(VI) ions and inhibited by 75 mg dm⁻³ initial chromium(VI) concentration since some inhibition occurred at lower concentrations.     

Effect of oxygen supply on cell growth and saponin production in bioreactor cultures of Panax ginseng

The effects of oxygen supply within the range 20.8–50% (using pure oxygen and air), on cell cultures of Panax ginseng were investigated in a balloon-type bubble bioreactor (5 L capacity, containing 4 L Murashige and Skoog medium, supplemented with 7.0 mg L⁻¹ indolebutyric acid, 0.5 mg L⁻¹ kinetin and 30 g L⁻¹ sucrose). A 40% oxygen supply was found to be optimal for the production of both cell mass and saponin yielding values of 12.8 g (DW) L⁻¹, 4.5 mg (g DW)⁻¹ on day 25, respectively. Low (20.8%, 30%) and high (50%) oxygen concentration supplies were unfavorable to cell growth and saponin accumulation. The results indicate that oxygen supplementation to bioreactor-based ginseng cultures was beneficial for biomass accumulation and saponin production.     

Effect of tree leaf as supplementation on nutrient digestion and rumen fermentation pattern in sheep grazing semi-arid range of India – II

A study was conducted to evaluate the effects of supplementing with different tree leaves on nutrient digestion, rumen fermentation and blood parameters of sheep. Thirty adult Malpura rams (39.0 ± 0.56 kg) were divided into five groups of six each. They were grazed as a single flock on a semi-arid rangeland and after the end of routine grazing period (08:00–17:00 h), first group (G1), which was not provided with any supplementation, served as control group. Second group (G2) was supplemented with 200 g of a conventional concentrate mixture per head per day, whereas third, fourth and fifth groups (G3, G4 and G5) were supplemented with approximately 200 g dry matter (DM) per day freshly cut foliage from Ailanthes excelsa, Azardirachta indica and Bauhinia racemosa, respectively. Protein content (g kg⁻¹ DM) in A. excelsa, A. indica and B. racemosa foliage was 197, 128 and 132, respectively. A. indica and B. racemosa foliages also contained 123.2 and 211.2 g kg⁻¹ DM condensed tannin (CT) with protein precipitating capacity (PPC) of 16.5 and 46.5 g kg⁻¹ DM. None of the tree leaves contained hydrolysable tannin (HT). Dry matter intake (DMI, g day⁻¹) was 591, 766, 865, 974 and 939 in G1, G2, G3, G4 and G5, respectively. Digestible crude protein (DCP) and metabolisable energy (ME) intakes in supplemented groups G2–G5 were higher (P < 0.05) compared to control (G1). Supplementation improved digestibility of all nutrients in all groups. Rumen fermentation study indicated lower (P < 0.05) ammonia and total N in the rumen liquor collected from G5 sheep compared to the other supplemented groups. Although haemoglobin (Hb, g dl⁻¹) levels showed small changes among groups, blood urea nitrogen (BUN, mg dl⁻¹) was lowest in G5 compared to the other groups. Initial BW were similar among the groups. After 60 days of experimental feeding, all animals maintained their BW, except sheep in the control group (G1), which lost BW. Results indicate that for adult sheep grazing on a semi-arid range, supplementation with a concentrate mixture could be replaced by tree leaves like A. excelsa, A. indica and B. racemosa, during the lean season to maintain their BW. In addition, supplementing with tree leaves containing condensed tannin has advantages in terms of N utilization.     

Antimicrobial activity of steady-state cultures of Bacillus sp. CCMI 1051 against wood contaminant fungi

The effect of changing dilution rate (D) on Bacillus sp. CCMI 1051 at dilution rates between 0.1 and 0.55 h⁻¹ in a glucose-limited medium was studied. Biomass values varied between 0.88 and 1.1 g L⁻¹ at D values of 0.15–0.35 h⁻¹. Maximal biomass productivity was found to be 0.39 g L⁻¹ h⁻¹, obtained at D = 0.35 h⁻¹ and corresponding to a 54.4% conversion of the carbon into cell mass. The highest rate of glucose consumption was 4.45 mmol g⁻¹ h⁻¹ occurring at D = 0.4 h⁻¹. The glucose concentration inside the chemostat was below the detection level starting to accumulate around 0.4 h⁻¹. Growth inhibition of fifteen strains of fungi by the broth of the steady-state cell-free supernatants was assessed. Results showed that the relative inhibition differ among the target species but was not influenced by the dilution rate changing.     

Poly-beta-hydroxybutyrate accumulation in Nostoc muscorum and Spirulina platensis under phosphate limitation

Nostoc muscorum and Spirulina platensis were grown under phosphate deficiency in order to investigate the role of internal phosphate pool and activity of alkaline phosphatase on poly-β-hydroxybutyrate (PHB) accumulation. PHB accumulation in N. muscorum increased to 22.7% of dry weight (dw) after 4 day of phosphate deficiency, while the internal phosphate pool reduced to the level of 0.02 μM mg dw⁻¹ at a maximum APase activity of 2.57 nM PNP mg dw⁻¹ h⁻¹. In contrary, S. platensis depicted maxima of 1.39 nM PNP mg dw⁻¹ h⁻¹ on day 30 of incubation, which was about 2 fold lower than the observed value of N. muscorum. PHB content in S. platensis remained low even after prolonged phosphate starvation, and a rise only up to 3.5% of dw was recorded on day 60 of phosphate deficiency. Supplementation of NADPH exogenously to S. platensis cultures grown under phosphate deficiency favoured PHB accumulation in 10, 20 and 30 days old cultures, but not in the cultures grown under phosphate deficiency for 60 days. The possible role of phosphate limitation on PHB accumulation is discussed.     

The adsorption of copper(II) ions on to dehydrated wheat bran (DWB): determination of the equilibrium and thermodynamic parameters

The adsorption of copper(II) ions on to dehydrated wheat bran (DWB), a by-product of the flour process, was investigated as a function of initial pH, temperature, initial metal ion concentration and adsorbent dosage. The optimum adsorption conditions were initial pH 5.0, initial copper concentration 100 mg l⁻¹, temperature 60 °C and adsorbent dosage 0.1 g. The adsorption equilibrium was described well by the Langmuir isotherm model with maximum adsorption capacity of 51.5 mg g⁻¹ of copper(II) ions on DWB. The observation of an increase in adsorption with increasing temperature leads to the result that the adsorption of copper(II) ions on DWB is endothermic in nature. The thermodynamic parameters such as enthalpy, free energy and entropy changes were calculated and these values show that the copper(II)-DWB adsorption process was favoured at high temperatures.     

SEC of mono-carboxymethyl cellulose (CMC) in a wide range of pH; Mark–Houwink constants

A method for determination of carboxymethyl cellulose (CMC) molecular weight (M_W) and chemical heterogeneity (degree of oxidation (DO)) using a bi-detector HPSEC (UV-detector online with refractometer) has been developed. It has been found that the use of 0.5 N NaOH or 0.4 M acetate buffer as the eluent ensures CMC separation according to M_W. It has been revealed that the universal calibration for the polyelectrolyte CMC and the neutral polymer dextran is valid under the conditions applied. The Mark–Houwink equations for CMC in 0.5 N NaOH and 0.4 M acetate buffer have been estimated to be [η]=5.37×10⁻⁴ M_W^0.73 and [η] =2.24×10⁻⁴ M_W^0.83 dl g⁻¹, respectively. The equation log K=1.64−4.00 ml g⁻¹ for CMC has been estimated. An approach for determining DO from adsorption at 290 or 313 nm has been developed.