Effect of farm yard manure and CaCO3 on the dry matter yield and nutrient uptake by oats (Avena sativa)

A pot culture experiment was conducted in loamy sand soil to study the effect of different levels of FYM and CaCO₃ on the dry matter yield and nutrients uptake by oats. Application of different levels of CaCO₃ (0, 2, 4 and 8%) and FYM (0, 0.5, 1,2%) resulted in significant increase in dry matter yield of oats. But, a little decrease in dry matter yield was obtained at 4% FYM. The interaction of FYM×CaCO₃ was also significant on dry matter yield of oats. There was a significant decrease in the concentration and uptake of P with increased levels of applied CaCO₃. But, application of FYM resulted in a significant increase in concentration and uptake of P. A significant increase in concentration and uptake of Ca was observed with the increasing levels of CaCO₃. The concentration of Ca decreased with the increased application of FYM in the presence as well as in the absence of added CaCO₃. However, at 0.5 and 1.0 percent FYM with 4 per cent CaCO₃ a little increase in Ca concentration was recorded. The Mg concentration in oat decreased significantly with the increasing levels of CaCO₃ and FYM. The effect of CaCO₃ levels was more pronounced in the absence as well as in the presence of FYM. The Mg uptake followed a different pattern. At 0 and 2% CaCO₃ and application of FYM @ 1 per cent the Mg uptake increased but then it decreased with increasing levels of FYM and CaCO₃ both alone as well as in the presence of each other. The concentration and uptake of Mn decreased with increasing levels of applied CaCO₃. However, in the absence of CaCO₃, the application of FYM increased the concentration and uptake of M_n in oats. In the presence of CaCO₃, Mn concentration decreased at all levels of FYM application but at 8 per cent CaCO₃ there was a slight increase in Mn concentration with 0.5, 2 and 4 percent FYM. Iron concentration and uptake was also affected adversely by increasing levels of CaCO₃ but FYM application removed the harmful effect of CaCO₃ to some extent.     

Effects of divalent cations and EDTA on spectral properties of phytochrome in particulate fractions from etiolated pea epicotyls

The photoreversible absorbance change of phytochrome in suspensionsof a 20,000xg particulate fraction (20kP) prepared from a 1,000xgsupernatant (1kS) of etiolated pea epicotyl extracts decreasedremarkably in the presence of 5 mM Cu²⁺, Zn²⁺ and Co²⁺, butremained unchanged in 5 mM Ca²⁺, Mg²⁺, Fe²⁺ or Mn²⁺. This spectraldistortion of phytochrome was more evident in soluble preparationsand in suspensions of pellets prepared from red light (R)-irradiatedtissues than it was in suspensions of pellets prepared in thedark from etiolated tissues that received no actinic irradiation. When Cu²⁺ was added to the red-light-absorbing form of phytochrome(Pr) in resuspended pellets prepared from R-irradiated tissues,the distortion of its difference spectrum took place after irradiationwith the first actinic R. In contrast, when Cu²⁺ was added tothe far-red-light-absorbing form of phytochrome (Pfr) in thesame resuspended pellet, no distortion was seen, unless thePfr in the pellet was first photoconverted to Pr and then photoconvertedback to Pfr. Spectral distortion of Pr remained small during dark incubationat 25°C when suspensions of 20kPs were prepared and incubatedwith a buffer containing EDTA, whether the 20kP was preparedfrom nonirradiated tissue or from R-irradiated tissues. But,when EDTA was added to a suspension of 20kP prepared from 1kS,after the 1kS was irradiated with R in the presence of 10 mMCaCl₂, the spectral distortion of Pr in 20kP occurred instantaneously. (Received April 14, 1980; )     

Nature of the phytochrome effect on the binding of glycolate oxidase to peroxisomes in vitro

The attachment of glycolate oxidase to the peroxisomal fraction derived from etiolated barley leaves (Hordeum vulgare L. cr. Dvir) is affected by light. The effect of red irradiation is reversed by subsequent far-red irradiation, indicating the involvement of phytochrome. This phytochrome effect is assumed to be related to phytochrome binding. Indeed, prevention by filipin (1.2·10^-6 mol g^-1 f wt) or cholesterol of phytochrome binding to membranes abolishes the effect of light on the interaction between glycolate oxidase and the peroxisomal fraction. Glycolate oxidase binding is affected by addition of quasi-ionophores such as gramicidin and filipin at a concentration of 0.6·10^-3 mol g^-1 f wt. This fact indicates that peroxisome-glycolate oxidase interaction may be affected by membrane potential. Since both ion transport and membrane potential are known to be affected by phytochrome, it is proposed that phytochrome acts in the light-induced modulation of glycolate oxidase attachment as a quasi-ionophore.Abbreviations GO glycolate oxidase - Pr and Pfr phytochrome forms absorbing in red and far-red, respectively - R and F red and far-red irradiation - Cumulative 20 Kp 20,000 g pellet obtained by centrifugation of the crude extract - 1 Kp 1,000 g pellet - 20 Kp 20,000 g pellet, obtained by centrifugation of 1 Kp supernatant - 1 Kp, 20 Kp and cumulative 20 Kp pellets obtained after density centrifugation through a sucrose cushion     

Yield of submerged paddy and uptake of Zn,P and N as affected by liming and Zn fertilizers

The effects of CaCO₃, Zn sources and levels on the yield of submerged paddy and uptake of Zn, P and N to paddy were studied in green-house at Haryana Agricultural University, Hissar. Powdered CaCO₃ was mixed at 0,4 and 8 per cent and Zn was added at 0,5 and 10 ppm through ZnSO₄.7H₂O, ZnO and Zn EDTA separately. Dry weight at tillering and heading and grain and straw at maturity decreased significantly with 4 and 8 per cent CaCO₃ in comparison to the control. Increasing Zn application increased the dry weight and grain yield. Zn EDTA gave highest yield of paddy followed by ZnSO₄.7H₂O and ZnO.Increasing the application of CaCO₃ from 0–8 per cent decreased the concentration and uptake of Zn and increasing Zn application from 0–10 ppm increased concentration and uptake of Zn in paddy at tillering, heading and maturity. Zn EDTA gave the highest concentration and uptake of Zn followed by ZnSO₄.7H₂O and ZnO. There was interaction between Zn sources and CaCO₃.The concentration and uptake of N and P in paddy dry matter at tillering and heading and straw and grain at maturity decreased as compared to control with increasing CaCO₃ addition. The concentration and uptake of N increased and that of P decreased in paddy dry matter straw and grain with increasing Zn application. The highest concentration of N was observed with ZnO, followed by ZnSO₄.7H₂O and Zn EDTA. But highest uptake of N was observed with Zn EDTA followed by ZnSO₄.7H₂O and ZnO. As regards concentration and uptake of P, it was highest with ZnO followed by ZnSO₄.7H₂O and Zn EDTA.     

Phytochrome in green tissue: Spectral and immunochemical evidence for two distinct molecular species of phytochrome in light-grown Avena sativa L.

A method is described for the extraction of phytochrome from chlorophyllous shoots of Avena sativa L. Poly(ethyleneimine) and salt fractionation are used to reduce chlorophyll and to increase the phytochrome concentration sufficiently to permit spectral and immunochemical analyses. The phototransformation difference spectrum of this phytochrome is distinct from that of phytochrome from etiolated shoots in that the maximum in the red region of the difference spectrum is shifted about 15 nm to a shorter wavelength. Immunochemical probing of electroblotted proteins (Western blotting), using a method sensitive to 50 pg, demonstrates the presence of two polypeptides in green tissue that bind antiphytochrome antibodies: a predominant species with a relative molecular mass (M_r) of 118000 and a lesser-abundant 124000-M_r polypeptide. Under nondenaturing conditions all of the 124000-M_r species is immunoprecipitable, but the 118000-M_r species remains in the supernatant. Peptide mapping and immunochemical analysis with monoclonal antibodies show that the 118000-M_r species has structural features that differ from etiolated-oat phytochrome. Mixing experiments show that these structural differences are intrinsic to the molecular species from these two tissues rather than being the result of post-homogenization modifications or interfering substances in the green-tissue extracts. Together the data indicate that the phytochrome that predominates in green-tissue has a polypeptide distinct from the well-characterized molecule from etiolated tissue.Abbreviations and symbols Ig immunoglobulin - M_r relative molecular mass - Pfr, Pr far-red-absorbing and red-absorbing forms of phytochrome respectively - SDS-PAGE sodium dodecyl sulfate-polyacrylamide gel electrophoresis - _max ^R , _max ^FR maxima of the phototransformation difference spectrum in the red and far-red region     

Effects of neutralizing agents on lactic acid production by Rhizopus oryzae using sweet potato starch

A neutralizing agent is usually employed to counteract the pH reduction during lactic acid fermentation by Rhizopus oryzae. Calcium carbonate (CaCO₃) is used as such a pH controlling agent. The low solubility of CaCO₃ in the fermentation broth could however lead to low efficiency in pH control and cause problems in the subsequent purification process. Therefore, an alternative agent in place of CaCO₃ was examined in this study. The effect of four different neutralizing agents, including CaCO₃, sodium hydroxide (NaOH), ammoniacal solution and sodium bicarbonate (NaHCO₃) on lactic acid production and the morphology of the pellets were investigated. Results indicated that CaCO₃ was still the preferred choice, because of the pellet morphology and the highest lactic acid concentration (43.3 g/L) obtained in the batch using 60 g/L of sweet potato starch as feedstock. It is noteworthy that the lactic acid purification is relatively easier when using NaHCO₃ instead of CaCO₃, due to the higher solubility of sodium lactate than calcium lactate. Therefore, even the batch with CaCO₃ had a slightly higher productivity (1.23 g/L/h) than the batch with NaHCO₃ (1.14 g/L/h), NaHCO₃ might be the first choice for process designers whenever recovery is vital.     

Light requirement,phytochrome and photoperiodic induction of flowering of Pharbits nil Chois

The low chlorophyll content of cotyledons of Pharbitis nil grown for 24 h in far-red light (FR) or at 18° C in white light from fluorescent lamps (WL) allows spectrophotometric measurement of phytochrome in these tissues. The (A) measurements utilize measuring beams at 730/802 nm and an actinic irradiation in excess of 90 s. The constancy of the relationship between phytochrome content and sample thickness confirms that, under these conditions of measurement, a true maximum phytochrome signal was obtained. These techniques have been used to follow changes in the form and amount of phytochrome during an inductive dark period for flowering. Following exposure to 24h WL at 18° C with a terminal 10 min red (R), P_fr was lost rapidly in darkness and approached zero in less than 1 h; during this period there was no change in the total phytochrome signal. Following exposure to 24 h FR with a terminal 10 min R, P_fr approached zero in 3 h, and the total phytochrome signal decreased by about half. The relevance of these changes to photoperiodic time measurement is discussed.Abbreviations BCJ irradiation from photographic ruby-red lamps - FR far-red light - P_fr far-red-absorbing form of phytochrome - P_r red-absorbing form of phytochrome - P total phytochrome content - R red light - WL white light from fluorescent lamps     

Spectral properties of soluble and pelletable phytochrome from epicotyls of etiolated pea seedlings

The red-light(R)-absorbing form of phytochrome (Pr) was detected spectrophotometrically in a 20,000 g particulate fraction prepared from a 1,000 g supernatant fraction from epicotyl tissue of pea (Pisum sativum L.) seedlings grown in the dark and only briefly exposed to dim green light. The difference spectrum of phytochrome in this fraction was essentially the same as that of soluble phytochrome from the same tissue. When the non-irradiated 20,000 g particulate fraction was incubated in the dark at 25° C, an absorbance change (decrease) of Pr after actinic red irradiation was found only in the far-red (FR) region. When the 20,000 g particulate fraction was irradiated with R and then incubated in the dark, the FR-absorbing form of phytochrome (Pfr) disappeared spectrally at a rate about half that in the soluble fraction, and the difference spectrum of the Pr which became detectable after dark incubation of the 20,000 g particulate fraction was markedly distorted. In contrast, Pfr in a 20,000 g particulate fraction prepared from tissues irradiated with R did not change optically during dark incubation at 25° C for 60 min, while Pfr in the soluble fraction from the same tissue disappeared in the dark. No dissociation of either Pr or Pfr from the 20,000 g particulate fraction was indicated during a 60-min dark incubation at 25° C, but Pfr in a 20,000 g particulate fraction prepared in vitro from R-irradiated 1,000 g supernatant fraction in the presence of CaCl₂ disappeared spectrally and the difference spectrum of Pr in the 20,000 g particulate fraction became quite distorted during the dark incubation.Abbreviations Pr red-light-absorbing form of phytochrome - Pfr far-red-light-absorbing form of phytochrome - FR far-red light - FR1 first actinic far-red light - FR2 second actinic far-red light - R red light - R1 first actinic red light - 1kS 1,000 g supernatant fraction - 20kS 20,000 g supernatant fraction - 20kP 20,000 g particulate fraction     

Phytochrome-mediated induction of phenylalanine ammonia-lyase in the cotyledons of tomato (Lycopersicon esculentum Mill.) plants

Phenylalanine ammonia-lyase (PAL; EC 4.3.1.5.) induction in cotyledons from 96-h dark-grown Lycopersicon esculentum Mill. was studied in response to continuous light and hourly light pulses (blue, red, far red). The increases of PAL promoted by blue and red pulses are reversed completely by immediately following 758 nm irradiations. The response to continuous red light could be substituted for by hourly 6-min red light pulses. The effect of continuous red treatments is mainly due to a multiple induction effect of phytochrome. In contrast to red light, hourly light pulses with far red and blue, light can only partially substitute for continuous irradiation. The continuous blue response could be due to a combination of a multiple induction response and of a high irradiance response of phytochrome. The continuous far red response, could represent a high irradiance response of phytochrome. Dichromatic irradiations indicate that phytochrome is the photoreceptor controlling the light response (PAL) in tomato seedlings.Abbreviations Norflurazon NF-4-chloro-5-(methylamino)-2-(,,,-trifluoro-m-tolyl)-3 (2H) pyridazinone - PAL phenylalanine ammonia-lyase - phytochrome photoequilibrium P_fr/P_tot - P_fr far-red absorbing form of phytochrome - P_r red absorbing form of phytochrome - P_tot total phytochrome: P_r+P_fr     

Coral acid rich protein selects vaterite polymorph in vitro

Corals and other biomineralizing organisms use proteins and other molecules to form different crystalline polymorphs and biomineral structures. In corals, it’s been suggested that proteins such as Coral Acid Rich Proteins (CARPs) play a major role in the polymorph selection of their calcium carbonate (CaCO₃) aragonite exoskeleton. To date, four CARPs (1–4) have been characterized: each with a different amino acid composition and different temporal and spatial expression patterns during coral developmental stages. Interestingly, CARP3 is able to alter crystallization pathways in vitro, yet its function in this process remains enigmatic. To better understand the CARP3 function, we performed two independent in vitro CaCO₃ polymorph selection experiments using purified recombinant CARP3 at different concentrations and at low or zero Mg²⁺ concentration. Our results show that, in the absence of Mg²⁺, CARP3 selects for the vaterite polymorph and inhibits calcite. However, in the presence of a low concentration of Mg²⁺ and CARP3 both Mg-calcite and vaterite are formed, with the relative amount of Mg-calcite increasing with CARP3 concentration. In all conditions, CARP3 did not select for the aragonite polymorph, which is the polymorph associated to CARP3 in vivo, even in the presence of Mg²⁺ (Mg:Ca molar ratio equal to 1). These results further emphasize the importance of Mg:Ca molar ratios similar to that in seawater (Mg:Ca equal to 5) and the activity of the biological system in a aragonite polymorph selection in coral skeleton formation.     

Nitrogen fixation of lucerne (Medicago sativa) in an acid soil: The use of rhizotrons as a model system to simulate field conditions

The effect of pelleting seeds of lucerne with lime was studied in an acid sandy soil. In pot experiments, the fraction of seedlings with crown nodules, i.e. nodules on the upper 10 mm of the taproot, increased from 26% to 71%. In rhizotrons, the application of CaCO₃ resulted in an even stronger response.An agar-contact method was used to study pH changes in the rhizosphere during a period up to 12 days. Application of 1.0 µmol of CaCO₃, in drops of 12 µL volume, resulted in an initial soil pH of 6.1 and yielded 75% crown nodulation. In the absence of CaCO₃, roots induced a pH increase from 5.1 (day 0) to 5.7 (day 12). However, this did not increase nodulation (5%). Obviously, this type of alkalinization does not overcome the acid-sensitive step of the nodulation process.     

Calcareous impact on arbuscular mycorrhizal fungus development and on lipid peroxidation in monoxenic roots

The present work underlined the negative effects of increasing CaCO₃ concentrations (5, 10 and 20 mM) both on the chicory root growth and the arbuscular mycorrhizal fungus (AMF) Glomus irregulare development in monoxenic system. CaCO₃ was found to reduce drastically the main stages of G. irregulare life cycle (spore germination, germinative hyphae elongation, root colonization, extraradical hyphae development and sporulation) but not to inhibit it completely. The root colonization drop was confirmed by the decrease in the arbuscular mycorrhizal fungal marker C16:1ω5 amounts in the mycorrhizal chicory roots grown in the presence of CaCO₃. Oxidative damage evaluated by lipid peroxidation increase measured by (i) malondialdehyde (MDA) production and (ii) the antioxidant enzyme peroxidase (POD) activities, was highlighted in chicory roots grown in the presence of CaCO₃. However, MDA formation was significantly higher in non-mycorrhizal roots as compared to mycorrhizal ones. This study pointed out the ability of arbuscular mycorrhizal symbiosis to enhance plant tolerance to high levels of CaCO₃ by preventing lipid peroxidation and so less cell membrane damage.     

Integral association of phytochrome with a membranous fraction fromAvena shoots: in vivo characterization and physiological significance

Phytochrome in the far-red light absorbing form (Pfr) was observed to disappear in vivo more rapidly from the non-cation-requiring pelletable phytochrome population than from the supernantant phytochrome population of oat seedlings given an increasing dark incubation after red irradiation. The amount of pelletable phytochrome in the red light absorbing form (Pr) remained relatively stable while supernatant Pr was lost. These observations indicated that supernant Pfr was subject to loss during the incubation, while pelletable Pfr was subject to both dark reversion and loss.During the incubation, the ability of far-red irradiation to reverse the red-induced increase in phytochrome pelletability was lost, with kinetics similar to those of the loss of pelletable Pfr.Far-red reversibility of the red-induced increase in coleoptile elongation correlated with the change intotal Pfr in both supernatant and pelletable phytochrome populations, but with the change in the ratio of Pfr to total phytochrome only in the pelletable phytochrome population.The possible significance of these results is discussed with reference to the action of phytochrome in the photocontrol of physiological growth responses.Abbreviations Pfr phytochrome in the far-red light absorbing form - Pr phytochrome in the red absorbing form - Ptot total phytochrome     

Induction of Calcium Carbonate by Bacillus cereus

The purpose of this research was to study how the bacteria Bacillus cereus (DCB1) utilizes calcium ions in a culture medium with carbon dioxide (CO₂) to yield calcium carbonate (CaCO₃). The bacteria strain DCB1 was a dominant strain isolated from dolomitic surfaces in areas of Karst topographies. The experimental method was as follows: a modified beef extract-peptone medium (beef extract 3.0 g, peptone 10 g, NaCl 5.0 g, CaCl₂ 2.0 g, glass powder 2.0 g, distilled water 1 L, and a pH between 6.5 and 7.5) was inoculated with B. cereus to attempt to induce the synthesis of CaCO₃. The sample was then processed by centrifugation every 24 h during the 7-day cultivation period. The pH, carbonic anhydrase (CA) activity, and the concentrations of both HCO^- ₃ and Ca²⁺ in the supernatant fluid were measured. Subsequently, precipitation in the culture medium was analyzed to confirm, or otherwise, the presence and if present, the formation, of CaCO₃. Methods used included X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and Energy Dispersive Spectroscopy (EDS). Meanwhile, the carbon source in the carbonate was classified by its isotope composition. Results showed that B. cereus can improve its pH value in this culture medium; concentrations of HCO^- ₃ and Ca²⁺ showed a significant decline over the duration of the cultivation period. CA activity reached its maximum during the second day; XRD, SEM, TEM, and isotope analysis all revealed the presence of CaCO₃ as a precipitate. Additionally, these results did not occur in an aseptic control group: no detectable level of CaCO₃ was produced therein. In conclusion: B. cereus can metabolize active materials, such as secretase, by its own growth and metabolism, and can either utilize atmospheric CO₂, or respire, to induce CaCO₃ production. Experimental evidence is offered for a concomitant CO₂ reduction and CaCO₃ induction by microorganisms.     

Organic Acid Production by Basidiomycetes: I. Screening of Acid-Producing Strains

Sixty-seven strains belonging to 47 species of Basidiomycetes were examined for their acid-producing abilities in glucose media, in both the presence and absence of CaCO₃, in stationary and shake cultures. Some strains were found to produce large quantities of oxalic acid. The oxalic acid-producing strains could be separated into two groups. Strains of one group (mostly brown-rot fungi) were able to produce oxalic acid, regardless of whether CaCO₃ was present in the medium. Strains of the other group (mostly white-rot fungi) were characterized by their ability to produce oxalic acid only when CaCO₃ was added to the medium. With the latter group, shake-culturing was generally more effective than stationary culturing in respect to acid production. In the CaCO₃-containing media, Schizophyllum commune, Merulius tremellosus, and Porodisculus pendulus were found to produce substantial amounts of L-malic acid as a main metabolic product, along with small quantities of oxalic and other acids in shake cultures. Especially, S. commune and M. tremellosus may be employed as malic acid-producing species.     

Aspects of phytochrome decay in etiolated seedlings under continuous Illumination

Summary The rate of total phytochrome decay in the dicotyledons Amaranthus caudatus, Mirabilis jalapa and Pisum sativum under continuous illumination with red, incandescent, and blue light depends on the P_FR/P_total maintained by each source. Amaranthus is an exception to this in that there is a deviation from firstorder decay kinetics under continuous illumination with incancdescent light. This deviation is probably not related to the chlorophyll present in the Amaranthus sample since chlorophyll-rich Pisum buds have the same phytochrome decay rate as epicotyl tissue under continuous incandescent light. Reports of a prolonged lag phase before the onset of first-order decay kinetics of phytochrome in Pisum have not been confirmed and the small lag phase observed in the present work can be accounted for by the time required to attain the P_FR/P_total ratio characteristic of blue light in a carotenoid rich tissue. In the monocotyledon, Avena sativa, and perhaps monocotyledons in general, decay rate is maximal at a low P_FR concentration and the decay curve is the same under continuous red, incandescent and blue light. This dicotyledon/monocotyledon difference with respect to saturation of phytochrome decay does not correlate with the other dicotyledon/monocotyledon difference, the presence or absence of dark reverions of P_FR to P_R, since the dicotyledons Amaranthus and Mirabilis that lack reversion still show no saturation of decay. Possible growth control by the P_FR/P_total ratio is discussed in relation to environmental changes in light quality.Research carried out at Brookhaven National Laboratory under the auspices of the U. S. Atomic Energy Commission.     

Evaluation of the mycological status of luncheon meat with special reference to aflatoxigenic moulds and aflatoxin residues

The luncheon meat samples analyzed, which were produced locally by the two main luncheon meat producing companies in Egypt were relatively highly contaminated either by moulds and yeasts in general, aflatoxigenic species and aflatoxin residues in particular. The most frequently encountered fungi from the samples were yeasts, Aspergillus niger, A. flavus, Penicillium chrysogenum, Rhizopus stolonifer, Mucor circinelloides. Less common were Cladosporium sphaerospermum, Alternaria alternata, Mycosphaerella tassiana, P. aurantiogriseum and P. oxalicum. The most important aflatoxigenic species, A. flavus, was isolated frequently. It was 10% of the total fungal isolates from both samples of the two companies. Seven luncheon meat samples out of 50 analyzed were positive for aflatoxin B₁ or B₁ and G₁, while all samples were negative for aflatoxins B₂, G₂, M₁ and M₂. Aflatoxin B₁ was detected only in 4 and 3 samples out of 25 analyzed from each of company A and B, respectively. The highest detectable level, 11.1 ppb, was recorded in a sample from company B and the least, 0.5 ppb, in a sample from company A. Aflatoxin G₁, at concentration of 3.2 ppb, was detected in only one sample of the aflatoxin B₁ – contaminated 3 samples of company B: this sample also had the highest level of aflatoxin B₁. Some luncheon meat samples had higher numbers of aflatoxigenic A. flavus than others, however these samples were negative for aflatoxins. The hazardous potential of such contamination will be discussed. This revised version was published online in June 2006 with corrections to the Cover Date.     

Biosorption of thorium (IV) by a Pseudomonas biomass

Lyophilized biomass of a Pseudomonas soilisolate adsorbed thorium (IV) (430 mg g^–1 dry wt) optimally at pH 4, with 91% of equilibrium loading being reached in 1 min. Equilibrium metal sorption showing conformity to Langmuir isotherm model suggested a monolayered thorium binding. Thorium binding remained unaffected or slightly affected (< 20% inhibition) in presence of equimolar (430 M) concentration of several interfering ions except Fe³⁺ (40% inhibition). More than 90% of loaded thorium could be recovered using 1 M CaCO₃, though mineral acids and Na₂CO₃ were also effective.     

Bioerosion caused by foraging of the tropical chiton Acanthopleura gemmata at One Tree Reef, southern Great Barrier Reef

The bioerosive potential of the intertidal chiton Acanthopleura gemmata on One Tree Reef was determined by quantification of CaCO₃ in daily faecal pellet production of individuals transplanted into mesocosms after nocturnal-feeding forays. Mean bioerosive potential was estimated at 0.16 kg CaCO₃ chiton⁻¹ yr⁻¹. Bioerosion rates were estimated for populations on two distinct chiton habitats, reef margin (0.013 kg CaCO₃ m⁻² yr⁻¹) and beachrock platform (0.25 kg CaCO₃ m⁻² yr⁻¹). Chiton density on the platform was orders of magnitude greater than on the reef margin. The surface-lowering rate (0.16 mm m⁻² yr) due to bioerosion by the beachrock population is a substantial contribution to the total surface-lowering rate of 2 mm m⁻² yr⁻¹ previously reported for One Tree Reef across all erosive agents. At high densities, the contribution of A. gemmata to coral reef bioerosion budgets may be comparable to other important bioeroders such as echinoids and fish.