Lifestyle of Korean mudskipper <Emphasis Type="Italic">Periophthalmus magnuspinnatus</Emphasis> with reference to a congeneric species <Emphasis Type="Italic">Periophthalmus modestus</Emphasis>

To investigate the life history and ecology of the mudskipper Periophthalmus magnuspinnatus, observations and collection were made on coastal mudflats in southern Korea. Periophthalmus magnuspinnatus was active from May to September on the mudflats, exclusively occupying rough and elevated or sloped mudflats of the seashore or the stream mouth, usually vegetated with halophilous grasses. The congeneric species, P. modestus, mainly occurred on extensive low-elevation and level mudflats with no visible vegetation. An apparent alternation of habitat use by P. modestus took place on mudflats at the stream mouth in mid-October, when P. magnuspinnatus began wintering in its burrow and P. modestus came onto the vacated mudflats to construct burrows for wintering. The active season for P. magnuspinnatus at 17°C or higher air temperature was a little shorter than that of P. modestus. Periophthalmus magnuspinnatus constructed a burrow for the entire season in the highest area of the intertidal mudflat, where they hid themselves during high tide or when frightened, whereas P. modestus were likely to use any burrow constructed by other animals or sunken places to hide. The main stomach contents of P. magnuspinnatus were crabs and gammarids. During the reproductive season from May to July, P. magnuspinnatus performed mating behaviors and constructed a spawning burrow similar to the ones known for P. modestus, except their body color turned dark and quivering body movements were observed in the mature male instead of a pink or orange body color and wiggling body movements as in P. modestus. Eggs, measuring 1.56–1.69 mm in major axis and 0.94–1.0 mm in minor axis, were laid on the ceiling and the side wall of the “J”-shaped spawning room generally known for Periophthalmus species. Young of both species started to occur on the mudflat in June.     

Contribution of leaf surface fungi to the air spora

High concentrations of airborne fungal spores frequently occur from spring through fall in temperate areas of the world. Although it is generally assumed that fungi on leaf surfaces are contributors to the air spora, little data are available comparing the types of fungi found on leaf surfaces with those in the atmosphere. Air sampling was carried out with a Burkard Spore Trap located on the roof of a building on the University of Tulsa campus using standard methods. Leaf samples were aseptically collected from Ulmus americana and Quercus palustris trees on campus, placed in sterile plastic bags, and brought to the lab. For each leaf, 4 cm² areas of both upper and lower leaf surfaces were swabbed and plated on malt extract agar with streptomycin. Cultures were incubated at room temperature for 5–7 days and then examined microscopically. Results were expressed as colony forming units (CFU)/cm². Twenty-one fungal taxa were identified from the air samples. The most abundant taxa were Cladosporium, ascospores, basidiospores, and Alternaria; together these four spore types comprised over 90% of the yearly total. Yeasts were the most abundant fungi isolated from both leaf types. Among the mycelial fungi were Phoma species, followed by Cladosporium and Alternaria. Overall twenty genera of filamentous fungi were identified. Yeasts and Phoma are normally splash dispersed and were not identified in the Burkard air samples. However, 10 taxa isolated from leaf surfaces were registered in air samples. Crude estimates of the leaf surface area of each tree suggest that the total fungal load was approximately 5.04×10⁸ CFU for Ulmus and 2.71×10⁸ CFU for Quercus. Of these levels, 19% were from fungi also detected in air samples. The data suggest that some leaf-surface fungi are major contributors to the air spora.     

Penicillium Mycobiota in Arctic Subglacial Ice

Fungi have been only rarely isolated from glacial ice in extremely cold polar regions and were in these cases considered as random, long-term preserved Aeolian deposits. Fungal presence has so far not been investigated in polar subglacial ice, a recently discovered extreme habitat reported to be inhabited exclusively by heterotrophic bacteria. In this study we report on the very high occurrence (up to 9000 CFU L⁻¹) and diversity of filamentous Penicillium spp. in the sediment-rich subglacial ice of three different polythermal Arctic glaciers (Svalbard, Norway). The dominant species was P. crustosum, representing on the average half of all isolated strains from all three glaciers. The other most frequently isolated species were P. bialowiezense, P. chrysogenum, P. thomii, P. solitum, P. palitans, P. echinulatum, P. polonicum, P. commune, P. discolor, P. expansum, and new Penicillium species (sp. 1). Twelve more Penicillium species were occasionally isolated. The fungi isolated produced consistent profiles of secondary metabolites, not different from the same Penicillium species from other habitats. This is the first report on the presence of large populations of Penicillium spp. in subglacial sediment-rich ice.     

The assessment of airborne microorganisms in large-scale composting facilities and their immediate surroundings

The number of airborne microorganisms in the area of large-scale composting facilities with different composting techniques (A: open facility using the intensive decomposition process [4000 t/year]. B: closed facility with compost containers [7000 t/year], C: closed facility with table-pile compositing and automatic turning equipment [22 000 t/year]) was investigated using impactor sampling systems (Andersen samplers). All counts carried out inside the closed facilities, especially during the turning process, showed values of >5.0 × 10⁵ CFU/m³ for viable bacteria and moulds with a proportion ofAspergillus fumigatus of up to 64%. Depending on the type of facility, different median values were determined inside the plant area. Counts were highest in the immediate area around the biofilter outside of Facility C (1.7 × 10⁴ CFU/m³ for bacteria and 9.5 × 10³ CFU/m³ for moulds). In view of the high load of ambient airborne microorganisms inside the composting facilities, adequate occupational health measures are urgently required. Counts determining the hazard to neighbourhood residents at distances of between 150 and 2000 m showed, depending on the facility, annual median values of 170–330 CFU/m³ for bacteria, 75–340 CFU/m³ for moulds, and 15–52 CFU/m³ forA. fumigatus. Higher individual counts — up to 3 × 10³ CFU/m³ for moulds and up to 350 CFU/m³ forA. fumigatus — were found as a result of specific climatic influences, (e.g. winds) and activities as well poor operation. Given the high proportion ofA. fumigatus in the exhaust air, this mould can serve as an indicator for the evaluation of the health risk. However, the maximum values found in the present study, may also be caused by other events in rural areas, (e.g. agricultural activities). With regard to neighbourhood residents, odour complaints are more important than pollution by microorganisms.     

Use of saguaro fruit by white-winged doves: isotopic evidence of a tight ecological association

We report the use of stable isotope and crop content analyses to quantify the use of saguaro (Carnegiea gigantea) nectar and fruit by migratory desert white-winged doves (Zenaida asiatica mearsnii). Saguaro resources had characteristically ¹³C-enriched CAM values (δ¹³C=–12.8±0.7‰ SD VPDB and –13.1±0.5‰ SD VPDB for nectar and fruit, respectively) relative to other food plants used by doves (δ¹³C_C3=–24.9±3.3‰ SD VPDB). The water contained in saguaro nectar and fruit was deuterium enriched (δD=19.6±2.0‰ SD VSMOW and 48.4±1.6‰ SD VSMOW for nectar and fruit, respectively) relative to other water sources (ranging from –41 to –19‰ VSMOW). During the fruiting season, there was a positive correlation between δ¹³C in dove liver tissues and percent of saguaro in crop contents. A two-point mixing model indicated that during the peak of saguaro fruit use, most of the carbon incorporated in dove tissues was from saguaro. Desert white-winged doves appear to be saguaro specialists. Averaged over the period when doves were resident, saguaro comprised about 60% of the total carbon incorporated into dove tissues. Tissue δ¹³C and δD of body water showed a significant positive correlation, indicating that doves were using saguaro as a source of both nutrients and water. However, at the peak of saguaro utilization, the doves’ body-water δD was more positive (by about 20‰) than saguaro fruit water. We hypothesize that this enrichment is due to fractionated evaporative water losses by doves. Using dove carbon isotope data and a two end-point mixing model we estimate that, on average, doves consume the equivalent of 128 saguaro fruits per season; each fruit contains on average 26.0±14.8 g SD of pulp (wet mass) of which 19.4 g is water. Stable isotopes have been used to produce qualitative re-constructions of animal diets. Our study shows that they can be used to provide quantitative estimates of the flow of nutrients from resources into consumers as well. Received: 30 September 1999 / Accepted: 23 March 2000     

Taxonomic diversity of aerobic organotrophic bacteria from clean vietnamese soils and their capacity for oxidation of petroleum hydrocarbons

The dominant species and abundance of the cultured aerobic organotrophic bacteria were determined in the clean soils of the Republic of Vietnam. The total number of organotrophs varied from 2.0 × 10⁵ to 5.8 × 10⁸ CFU/g soil. A considerable fraction of the bacterial population (1.1 × 10⁵–9.5 × 10⁶ CFU/g soil) was able to utilize petroleum hydrocarbons as the sole carbon and energy source. Most of the organisms obtained in pure cultures were gram-positive bacteria; over 70% were hydrocarbon-oxidizing organisms. Analysis of 16S rRNA gene sequences resulted in tentative determination of the taxonomic position of 22 strains, with 12 belonging to the Firmicutes, 4, to the Proteobacteria, and 6 to the Actinobacteria. The most common bacteria capable of hydrocarbon oxidation belonged to the genera Acinetobacter, Bacillus, Brevibacillus, Chromobacterium, Cupriavidus, Gordonia, Microbacterium, Mycobacterium, and Rhodococcus. Some of the isolated Bacillus and Staphylococcus strains, as well as one Pseudomonas and one Sinomonas strain, did not utilize hydrocarbons. Gram-positive degraders, especially members of the order Actinomycetales, which exhibited high hydrocarbon-oxidizing activity, gained competitive advantage in the presence of hydrocarbons. This microbial group probably plays an important role in hydrocarbon degradation in tropical soils. Thus, Vietnamese soils, which had no history of petroleum contamination, support numerically significant and taxonomically diverse populations of h ydrocarbon-oxidizing bacteria.     

Pathogenic bacteria associated with lesions and thallus bleaching symptoms in the Japanese kelp Laminaria religiosa Miyabe (Laminariales,Phaeophyceae)

During early Spring (April–May) when the seawater salinity drops suddenly and the seawater temperature increases drastically, severe lesions and thallus bleaching were observed in the Laminaria religiosa population at Oshoro Bay, Otaru, Hokkaido, Japan. The healthy and diseased kelp blades were collected and subjected to enumeration of total number of culturable bacteria and bacterial species. Bacterial enumerations were done using 3 different media formulations; high-nutrient media (Media 1), low-nutrient media (Media 2) and modified low-nutrient media with 5% kelp extract (Media 3). Seven bacterial species were isolated from the healthy kelp. These were Alcaligenes aquamarinas, Alteromonas sp., Azomonas agilis, Azotobacter beijerinckii, Escherichia coli, Halobacterium sp. and Halococcus sp. All 7 bacterial species were isolated on Media 2 and Media 3, but only 5 species were isolated using Media 1 with the absence of Halobacterium sp. and Halococcus sp. Highest total number of culturable bacteria was 2050 CFU/cm² on Media 3. Eight species of bacteria were isolated from the diseased kelp thallus with the addition of Erwinia amylovora. All 8 bacteria grew on Media 2 and Media 3, but only 6 species were isolated using Media 1 with the absence of Halobacterium sp. and Halococcus sp. Highest total number of culturable bacteria was 5830 CFU/cm² on Media 3. However, only 3 species were isolated from the lesioned area. The most abundant species was Alteromonas sp. followed by Halococcus sp. and Alcaligenes aquamarinas. The surface bacteria showed best growth on Media 3. Scanning Electron Microscopic images of the healthy and diseased thallus gave distinctive evidence of the severity of the lesions as well as the relative abundance in the bacterial population. In an effort to identify the symptoms causative organism, the isolated bacterial species were cultured and used to test Koch's postulates. Out of the 8 species, only Alteromonas sp. induced lesions on the axenic kelp blades. The inoculated bacteria were also re-isolated without any significant contamination. Hence, Alteromonas sp. is suggested as the possible disease causing organism.     

Trends of fumonisin contamination and animal intoxication through monitoring 1991 to 1997 corn crop in the State of Paraná, Brazil

Eleven feed samples associated with six animal (horse and poultry) intoxication outbreaks (1991) in the state of Paraná, Brazil, were evaluated for fungal and fumonisin contamination. In order to estimate the␣trend of livestock intoxication, fumonisin contamination was monitored in corn produced both at the commercial level (1991, 1995 crop), and in an experimental field at a local Agronomy Institute (1997 crop). The total mould count in the feed samples ranged from 2.9 × 10³ to 1.9 × 10⁷ CFU/g, with Fusarium verticillioides as the predominant species, at a high count of 2.4 × 10⁴–6.5 × 10⁵ CFU/g. Fumonisins (FB₁ + FB₂) were detected in all corn-based feed samples at levels ranging from 2.89 to 14.54 μg/g. All 27 Northern corn samples (1991 crop) were contaminated with fumonisins at levels ranging from 2.32 to 16.64 μg/g. Twenty-six (96.3%) out of 27 corn samples from the Central-Southern region (1995 crop) were positive for fumonisins (FB₁+FB₂), with the range of 0.07–3.66 μg/g, while all 37 Northern samples (1995 crop) were contaminated with fumonisins ranging from 0.57 to 9.97 μg/g. Twenty-one out of 37 corn samples from the Northern region (1997 crop) were positive for fumonisins, but at low level (range of 0.05–2.67 μg/g). The results showed a decreasing trend in fumonisin contamination over the years. Nowadays animal intoxication outbreaks rarely occur in this State, as both animal producers and feed industries have become conscious about monitoring of corn and other raw materials at the quality control level.     

Piscivorous birds as top predators and fishery competitors in the lagoon ecosystem

Trophic patterns of omnivorous freshwater shrimps, Exopalaemon modestus and Macrobrachium nipponensis, were investigated in two shallow eutrophic lakes by using stable isotope analysis. δ¹⁵N and δ¹³C of M. nipponensis and E. modestus increased with increasing body weight, which might be attributed to larger individuals ingesting organisms that feed higher up the food chain and/or increased assimilation of benthic food items with enriched isotopic signatures. Of the freshwater shrimps occurring in the studied lakes, those from Lake Taihu had significantly elevated δ¹⁵N and δ¹³C values (4.3‰ and 1.8‰, respectively) compared with those from the less eutrophic Lake Chaohu, indicating that the isotopic signature might partially reflect the trophic states of their habitats. Mixing model results suggested that the benthic food web provides the primary carbon source for both shrimp species, and that E. modestus assimilated relatively more pelagic food sources than M. nipponensis in these lakes. Handling editor: S. Wellekens     

Purification and properties of fluoroacetate dehalogenase from <Emphasis Type="Italic">Pseudomonas fluorescens</Emphasis> DSM 8341

The degradation of fluoroacetate by microorganisms has been established for some time, although only a handful of dehalogenases capable of hydrolyzing the stable C–F bond have been studied. Pseudomonas fluorescens DSM 8341 was originally isolated from soil and readily degrades fluoroacetate, thus it was thought that its dehalogenase might have some desirable properties. The enzyme was purified from cell-free extracts and characterised: it is a monomer of 32,500 Da, with a pH optimum of 8 and is stable between pH 4 and 10; its activity is stimulated by some metal ions (Mg²⁺, Mn²⁺ and Fe³⁺), but inhibited by others (Hg²⁺, Ag²⁺). The enzyme is specific for fluoroacetate, and the K _m for this substrate (0.68 mM) is the lowest determined for enzymes of this type that have been investigated to date.     

一株分离自流浪猫的猪链球菌9型的分子生物学鉴定北大核心CSCD

【目的】猪链球菌是一种能感染人和猪的人畜共患病病原,并且还可零星感染多种哺乳动物。本试验旨在调查流浪猫携带猪链球菌的情况。【方法】在流浪猫身上分离猪链球菌,经血清凝集实验和PCR检测,鉴定其血清型;经多序列位点分型分析,鉴定其ST型;将所分离的细菌与Gen Bank上已公布的猪链球菌构建16S rRNA的系统发育树,分析该菌株与其他猪链球菌的亲缘关系;药敏纸片法分析其耐药性;小鼠攻毒试验分析其毒力。【结果】本试验在流浪猫身上分离到一株猪链球菌,命名为m70,其血清型为9型。多序列位点分型显示,m70株属于一个新的ST型。与Gen Bank上已公布的猪链球菌16S rRNA进行系统发育树分析,结果显示m70属于一个单独的分支。m70与临床菌株的耐药情况相似,对四环素耐药,对红霉素中介耐药,对氨苄西林敏感。小鼠攻毒试验显示,感染10~8 CFU剂量m70的小鼠,死亡率达到60%–80%（3/5–4/5）,3次攻毒试验的平均LD（50）为5.1×107 CFU;而本实验室保存的猪链球菌强毒株HA9801感染小鼠的平均LD（50）为3.9×107 CFU,两者之间没有显著差异（P〈0.05）。【结论】从流浪猫身上分离得到的猪链球菌m70属于优势血清型,且毒力较强,提示一些流行血清型的猪链球菌强毒株具有从流浪猫传染人的潜在风险。     

High diversity of diazotrophic bacteria associated with the carnivorous plant Drosera villosa var. villosa growing in oligotrophic habitats in Brazil

Drosera villosa var. villosa A. St.-Hil is a carnivorous plant that grows in Brazilian flooded soils very poor on nutrients, including low levels of N. Under these conditions, the plant shows vigorous growth, low root number, low number of captured prey (less than 50%) and a great assemblage of bacteria associated with the roots and leaves that grow in N-free medium. These preliminary results have led us to investigate the number of colony forming units (log CFU) in the roots (rhizosphere and endorhizosphere) and leaves (phyllosphere and endophyllosphere) of D. villosa var. villosa by the tenfold serial dilution technique in two N-free culture media. The results showed that the phyllosphere had 6.65 log CFU g dry leaf⁻¹ and the rhizosphere 6.47 log CFU g dry soil⁻¹, with the lowest value detected in the endophyllosphere (4.39 log CFU g dry leaf⁻¹). Sixty-three different bacteria morphotypes were isolated from the surface and interior of the roots and leaves and the amplification of the DNA with specific primers detected the nifH gene in 34 of those strains. The DNAs of the 34 strains were compared by the BOX-PCR technique and a great diversity was observed, with the bacteria clustering at a final level of similarity of only 12%. The strains were also submitted to the partial sequencing of the 16S rRNA gene and several genera of N₂-fixing bacteria were detected, including Bacillus, Burkholderia, Methylobacterium, Paenibacillus, Pseudomonas and Sphingomonas.     

Distribution,community structure and production of fishes in the upper Speed River,Ontario: a preimpoundment study

Synopsis The upper Speed River, on which a dam was under construction, was surveyed through fourteen qualitative and six quantitative collections to determine the distribution of fishes in the river above Guelph, Ontario and in a tributary, Luteral Creek. At the quantitative localities the removal method was used to estimate density and standing crop of all species. At three of these localities age and growth of the dominant species were determined and total ecological production calculated. Two approaches to the estimation of production for the 0–1 age class were compared and found to result in differences of 33–39% in the estimates of total production, thus illustrating the extent to which methodology may affect such estimates The dominant species in the river were, Semotilus atromaculatus, Notropis cornutus, Pimephales notatus, Rhinichthys atratulus, Hypentelium nigricans, Catostomus commersoni, Ambloplites rupestris, Micropterus dolomieui and Etheostoma flabellare. Density ranged from 11126 to 74765 individuals per hectare and standing crop from 32.4 to 190.0 kg ha⁻¹. Production values at the three localities were 15, 19 and 54 kg ha⁻¹ yr⁻¹ , and are low compared with estimates for other fluvial systems. Comparison with a 1951 survey of the Speed River revealed considerable changes in the composition and distribution of fish species. The ranges of several cold-water species had contracted towards the headwaters, whereas several warm-water species had extended their ranges up the river     

Solubilization of organic and inorganic phosphates by three highly efficient soil bacterial isolates

Screening soil samples collected from a diverse range of slightly alkaline soil types, we have isolated 22 competent phosphate solubilizing bacteria (PSB). Three isolates identified as Pantoea agglomerans strain P5, Microbacterium laevaniformans strain P7 and Pseudomonas putida strain P13 hydrolyzed inorganic and organic phosphate compounds effectively. Bacterial growth rates and phosphate solubilization activities were measured quantitatively under various environmental conditions. In general, a close association was evident between phosphate solubilizing ability and growth rate which is an indicator of active metabolism. All three PSB were able to withstand temperature as high as 42°C, high concentration of NaCl upto 5% and a wide range of initial pH from 5 to 11 while hydrolyzing phosphate compounds actively. Such criteria make these isolates superior candidates for biofertilizers that are capable of utilizing both organic and mineral phosphate substrates to release absorbable phosphate ion for plants.     

Nitrite-driven anaerobic ATP synthesis in barley and rice root mitochondria

Mitochondria isolated from the roots of barley (Hordeum vulgare L.) and rice (Oryza sativa L.) seedlings were capable of oxidizing external NADH and NADPH anaerobically in the presence of nitrite. The reaction was linked to ATP synthesis and nitric oxide (NO) was a measurable product. The rates of NADH and NADPH oxidation were in the range of 12–16 nmol min⁻¹ mg⁻¹ protein for both species. The anaerobic ATP synthesis rate was 7–9 nmol min⁻¹ mg⁻¹ protein for barley and 15–17 nmol min⁻¹ mg⁻¹ protein for rice. The rates are of the same order of magnitude as glycolytic ATP production during anoxia and about 3–5% of the aerobic mitochondrial ATP synthesis rate. NADH/NADPH oxidation and ATP synthesis were sensitive to the mitochondrial inhibitors myxothiazol, oligomycin, diphenyleneiodonium and insensitive to rotenone and antimycin A. The uncoupler FCCP completely eliminated ATP production. Succinate was also capable of driving ATP synthesis. We conclude that plant mitochondria, under anaerobic conditions, have a capacity to use nitrite as an electron acceptor to oxidize cytosolic NADH/NADPH and generate ATP.     

Molecular identification of intestinal microflora in Takifugu niphobles

We investigated the intestinal microflora of coastal fish including Takifugu niphobles using both culture techniques and library cloning. As a result, the numbers of bacteria appeared on agar media were 1.0 × 10⁴ to 1.4 × 10⁹ CFU/g (colony forming units/gram), whereas those of total bacteria stained with 4′,6-diamidino-2-phenylindole were 4.7 × 10¹⁰ to 1.9 × 10¹¹ cells/gram, irrespective of different fish species. In addition, the culture technique showed that the intestinal microflora in all specimens was mainly composed of the genus Vibrio. In contrast, the direct count method showed that spirochaetes with length of 2.5-4.5 μm were present in the intestinal contents of T. niphobles at high densities, whereas such bacteria could not be detected in those of other fish species. Library cloning yielded the sequences of 16S rRNA genes that were divided into seven taxonomic categories of bacteria including Actinobacteria, Bacilli, Clostridia, Gammaproteobacteria, Mollicutes, Spirochaetes and an unclassified bacterial group. These results demonstrate that the molecular diversity of the intestinal bacteria in T. niphobles based on the clone library method reflects the direct observation by fluorescence microscopy to some extent.     

Degradation of Microcystin-RR by Sphingomonas sp. CBA4 isolated from San Roque reservoir (Córdoba – Argentina)

We report the aerobic biodegradation of Microcystin-RR (MC-RR) by a bacterial strain isolated from San Roque reservoir (Córdoba – Argentina). This bacterium was identified as Sphingomonas sp. (CBA4) on the basis of 16S rDNA sequencing. The isolated strain was capable of degrading completely MC-RR (200 μg l⁻¹) within 36 h. We have found evidence that MC-RR biodegradation pathway by this Sphingomonas sp. strain would start by demethylating MC-RR, affording an intermediate product, which is finally biodegraded by this strain within 72 h. Our results confirm that certain environmental bacteria, living in the same habitat as toxic cyanobacteria, have the capability to perform complete biodegradation of MC, leading to natural bioremediation of waterbodies. The bacterium reported here presents genetic homologies with other strains that degrade MC-LR. However, initial demethylation of MC-RR has been not described previously, raising questions on the probable presence of different biodegradation pathways for different MC variants.     

Acetylene reduction and indoleacetic acid production by Azospirillum isolates from Cactaceous plants

Azospirillum isolates were obtained from rhizosphere soil and roots of three cactaceae species growing under arid conditions. All Azospirillum isolates from rhizosphere and roots ofStenocereus pruinosus andStenocereus stellatus were identified asA. brasilense; isolates of surface-sterilized roots fromOpuntia ficus-indica were bothA. brasilense andA. lipoferum. Azospirilla per g of fresh root in the three species ranged from 70×10³ to 11×10³. The most active strains in terms of C₂H₂ reduction (25–49.6 nmol/h·ml) and indoleacetic acid (IAA) production (36.5–77 μg/ml) were those identified asA. brasilense and isolated from Stenocereus roots.A. lipoferum isolated from Opuntia roots produced low amounts of IAA (6.5–17.5 μg/ml) and low C₂H₂-reduction activity (17.8–21.2 nmol/h·ml).     

Effect of aluminium on metabolism of starch and sugars in growing rice seedlings

The effect of increasing concentrations of Al₂(SO₄)₃ in situ on the content of starch, sugars and activity behaviour of enzymes related to their metabolism were studied in growing seedlings of two rice cvs. Malviya-36 and Pant-12 in sand cultures. Al₂(SO₄)₃ levels of 80 and 160 μM in the growth medium caused an increase in the contents of starch, total sugars as well as reducing sugars in roots as well as shoots of the rice seedlings during a 5–20 days growth period. The activities of the enzymes of starch hydrolysis α-amylase, β-amylase and starch phosphorylase declined in Al-exposed seedlings, whereas the activities of sucrose hydrolyzing enzymes sucrose synthase and acid invertase increased in the seedlings due to Al³⁺ treatment. The enzyme of sucrose synthesis, sucrose phosphate synthase showed decreased activity in Al³⁺ treated seedlings compared to controls. Results suggest that Al³⁺ toxicity in rice seedlings impairs the metabolism of starch and sugars and favours the accumulation of hexoses by enhancing the activities of sucrose hydrolyzing enzymes.     

Bacterial species in raw and cured compost from a large-scale urban composter

Summary Raw and cured compost samples from a large-scale urban composter were studied over a period of eight months to gain information on bacterial species present. Total viable, aerobic heterotrophic bacteria, lactose-positive bacteria, antibiotic and metal-resistant bacteria and thermophilic bacteria were enumerated. Both raw and cured compost samples contained metal and antibiotic-tolerant bacteria (–1 compost) as well as high numbers (as high as Log 7.4 CFU g^–1 dry weight compost) of thermophilic bacteria isolated by growth at 55 °C. Selected colonies were also identified using the Biolog 95 substrate identification system.Escherichia coli andSalmonella spp. were not detected in compost samples.