Sediment microbial respiration in a synoptic survey of mid‐Atlantic region streams

1. The rate of microbial respiration on fine‐grained stream sediments was measured at 196 first‐ to third‐order sites in the mid‐Atlantic region of the United States.
2. Sample collection took place between April and July in 1993, 1994 and 1995.
3. Study streams were randomly selected from the United States Environmental Protection Agency's (USEPA) River Reach File (RF3) using the sample design developed by USEPAs Environmental Monitoring and Assessment Programme (EMAP).
4. Respiration rate ranged from 0 to 0.622 g O ₂ g^–1 ash‐free dry mass (AFDM) h^–1, and was significantly correlated with stream temperature, water chemistry and physical habitat.
5. Respiration rate was significantly higher in streams from the Chesapeake drainage area compared to those from the Ohio drainage area, and in streams from the Northern Appalachian Plateau and Uplands and Central Appalachian Valleys ecoregions compared with streams from the Blue Ridge and Central Appalachian Plateau ecoregions.
6. Respiration was not significantly different among stream orders or between years.     

Phototrophic growth on n-fatty acids by species of the genus Rhodocyclus sensu Imhoff et al.

Abstract Type strains of Rhodocyclus purpureus, R. gelatinosus and R. tenuis along with three local isolates of R. gelatinosus were tested for growth in the light on n -fatty acids ranging in chain length from C₅ (valerate) to C₂₂ (docosanoate).
R. purpureus , the type species of the genus, was anomalous in its limited ability to grow on n -fatty acids; no fatty acids of chain length greater than C₉ (nonanoate) were utilized. R. gelatinosus and R. tenuis , on the other hand, utilized all fatty acids in the range C₅ to C₁₈ inclusive. R. gelatinosus showed some restricted ability to use C₂₀ (eicosanoate) and C₂₂ (docosanoate) fatty acids.     

Fumonisin B1 production by Fusarium proliferatum strains isolated from Allium fistulosum plants and seeds in Japan

Aims:  To test the fumonisin B₁ - producing ability of Fusarium proliferatum strains isolated from Welsh onion ( Allium fistulosum ) plants and seeds of commercial cultivars in Japan and to examine the applicability of PCR-based assays to discriminate between fumonisin B₁-producing and nonproducing isolates.
Methods and Results:  Fumonisin B₁ levels in 20 Fusarium isolates obtained from Welsh onion plants and seeds of seven commercial cultivars were determined by HPLC. Thirteen of the 20 isolates produced fumonisin B₁. PCR assay with FUM1 gene-specific primers amplified a DNA fragment (700 bp) only from fumonisin-producing isolates.
Conclusions:  Fusarium proliferatum isolates that can produce fumonisin B₁ were often associated with wilted Welsh onion plants and seeds of some commercial cultivars. The PCR assay with FUM1 gene-specific primers has the potential to discriminate between fumonisin B₁-producing and nonproducing isolates.
Significance and Impact of the Study:  This study revealed that F. proliferatum producing fumonisin B₁ is associated with Welsh onion plants and that commercial cultivar seeds may be contaminated with the fungus. PCR amplification of FUM1 gene can be a useful tool for the rapid identification of fumonisin B₁-producing F. proliferatum isolates.     

Phospholipids of Fusobacterium spp.

The aim of this study was to analyse individual polar lipid analogues, within each lipid family present, of fusobacteria using fast atom bombardment mass spectrometry (FAB-MS). Polar lipid extracts were prepared, washed and dried. Samples, dispersed in a matrix of m -nitrobenzyl alcohol, were analysed by negative ion FAB-MS using xenon as the reagent gas. Major anion peaks observed in the low mass region of mass/charge (m/z), 211, 221, 225, 227, 239, 241, 249, 251, 253, 255, 273, 277, 279, 281, 289 and 291, were consistent with the presence of C_13:1, C_14:3, C_14:1, C_14:0, C_15:1, C_15:0, C_16:3, C_16:2, C_16:1, C_16:0, unknown, C_18:3, C_18:2, C_18:1, unknown and C_19:3 carboxylate anions. In the high mass region, major anion peaks observed with m/z 644, 646, 648, 660, 662, 672, 673, 674, 686, 688, 689, 690, 698, 700, 701, 703, 714, 716, 717 and 719 were consistent with the presence of phosphatidylethanolamine (PE) (29:2), PE (29:1), PE (29:0), PE (30:1), PE (30:0), PE (31:2), first isotope of PE (31:2), PE (31:1), PE (32:2), PE (32:1), first isotope peak of PE (32:1), PE (30:0), PE (33:3), PE (33:2), phosphatidylglycerol (PG) (31:3), PG (31:2), PE (34:2), PE (34:1), PG (32:2) and PG (32:1). We conclude that FAB-MS can provide data on individual analogues of PE and PG from Fusobacterium spp. not readily obtained by other means. Furthermore, the phospholipid profile is diagnostic for the genus.     

Lactobacillus reuteri CRL 1098 prevents side effects produced by a nutritional vitamin B12 deficiency

Aims:  To evaluate the efficiency of the vitamin B_12-producing Lactobacillus reuteri CRL1098 strain in preventing the symptoms caused by a nutritional cobalamin-deficient diet in pregnant female mice and their weaned offspring.
Methods and Results:  Pregnant female mice were divided into three groups: animals fed with a B₁₂-deficient diet (DD), animals fed with DD plus L. reuteri CRL1098 and animals fed with a B₁₂-sufficient diet. The animals received the different feedings from the end of gestation up to weaning. At the end of the trials, they and their corresponding offspring were bled to determine haematological, immunological and histological parameters. The administration of the pseudovitamin B₁₂-producing strain prevented the symptoms observed in female and weaned young animals fed with a nutritional B₁₂-deficient diet.
Conclusions:  Our data suggest that the pseudovitamin B₁₂ produced by L. reuteri CRL1098 is biologically active and effective in preventing the pathologies caused by the nutritional deficiency of B₁₂ both in pregnant mice and their offspring.
Significance and Impact of the Study:  The ability of L. reuteri CRL1098 to prevent a nutritional vitamin deficiency was demonstrated for the first time. The addition of a GRAS micro-organism to complement the B₁₂ content in deficient foods is an interesting biotechnological alternative.     

Distribution of C3 and C4 grasses along an altitudinal gradient in Central Argentina

The distribution pattern of C₃ and C₄ grasses was studied in eight sites located between 350 m and 2100 m along an altitudinal gradient in Central Argentina. Of 139 taxa fifty-nine are C₃ and eighty C₄. Species of the C₃ tribes (Stipeae, Poeae, Meliceae, Aveneae, Bromeae and Triticeae) and C₃ Paniceae species increase in number at higher elevations; only one C₃ species was found below 650 m. C₄ Aristideae, Pappophoreae, Eragrostideae, Cynodonteae, Andropogoneae and Paniceae increase at lower altitudes. The floristic crossover point is at about 1500 m; the ground cover cross-over point is at about 1000 m. Analysis of the relationships between % C₄ species along the gradient and nine climatic and environmental variables showed the highest correlation with July mean temperature, but all temperature variables show highly significant correlations with % C₄. Correlation with annual rainfall is lower but also significant. These results are consistent with previous research showing the relative importance of C₄ grasses as temperature increases. C₃ species make a high contribution to relative grass coverage below the C₃/C₄ floristic crossover point but are rare below 1000 m.     

Uptake and utilization of n-octacosane and n-nonacosane by Arthrobacter nicotianae KCC B35

Arthrobacter nicotianae KCC B35 isolated from blue-green mats densely covering oil sediments along the Arabian Gulf coast grew well on C₁₀ to C₄₀ n -alkanes as sole sources of carbon and energy. Growth on C₂₀ to C₄₀ alkanes was even better than on C₁₀ to C₁₈ alkanes. Biomass samples incubated for 6 h with n -octacosane (C₂₈) or n -nonacosane (C₂₉) accumulated these compounds as the predominant constituent alkanes of the cell hydrocarbon fractions. The even chain hexadecane C₁₆ and the odd chain pentadecane C₁₅ were the second dominant constituent alkanes in C₂₈ and C₂₉ incubated cells, respectively. n -Hexadecane-incubated cells accumulated in their lipids higher proportions of C₁₆-fatty acids than control cells not incubated with hydrocarbons. On the other hand, C₂₈ and C₂₉-incubated cells did not contain any fatty acids with the equivalent chain lengths, but the fatty acid patterns of the cell lipids suggest that there should have been mid-chain oxidation of these very long chain alkanes. This activity qualifies A. nicotianae KCC B35 to be used in cocktails for bioremediating environments polluted with heavy oil sediments.     

Photosynthesis in Salsola Species (Chenopodiaceae) from Southern Africa Relative to their C4 Syndrome Origin and their African-Asian Arid Zone Migration Pathways

Abstract: Over 60 Salsola species of Chenopodiaceae from South Africa were studied for their photosynthesis type, using δ¹³C analysis and light microscopy of leaf anatomy. These species cover about 70 % of the total list of Southern African Salsola species and grow naturally in South and Southwest African desert regions. All species are shrubby forms and belong to the single subsection Caroxylon. Only C₄ photosynthesis was found in the Salsola species determined with ¹³C/¹²C carbon isotope discrimination values that ranged from - 11.04 to - 14.03 % (PDB), plus the presence of a Kranz type assimilation tissue anatomy. The apparent absence of C₃ in Salsola in South and Southwest Africa and the known presence of C₃ and C₃ - C₄ intermediate photosynthesis in Caroxylon, Salsola species in Asia strongly indicate that the genus Salsola originated in Asia and later migrated to South Africa.     

Late Ordovician-Early Silurian fluctuations in sea level from eastern Anticosti Island, Quebec

Over 1,000 m of Upper Ordovician to Lower Silurian mixed carbonate and clastic strata on Anticosti Island are nearly tectonically undisturbed, despite their proximity to the Northern Appalachians fronting Quebec's Gulf of St. Lawrence. Natural cliffs exposed along the coast and rivers in the eastern part of the island make a relatively conformable sequence belonging to the Ashgill and Llandovery Series. Fossil communities interpreted as depth-associated in life are especially repetitious in the Becscie, Gun River, Jupiter, and Chicotte Formations (Llandovery Series), and to a lesser degree in the Upper Vaureal and Ellis Bay Formations (Ashgill Series). Preliminary study of the pattern of changeovers in Eocoelia, Pentamerus and Stricklandia communities suggests that Anticosti seas deepened and shallowed three and a half times during the Early Silurian. High water peaks were reached during B₁-B₂, C₁-C₂ and C₄-C₅ times, with a final deepening trend beginning in late C₅ time. Age determinations of these events are based on the occurrence of graptolites (with some new records from Anticosti) keyed to the standard graptolite zones, and species of the Eocoelia lineage are also useful for correlation. The profile of the Anticosti sea-level curve compares well with other curves reconstructed from the Lower Silurian of New York, Michigan, and Iowa. Widespread synchronism in sea-level changes on the North American platform is thus corroborated.     

Effects of elevated oxygen tensions on acetylene reduction in Alnus incana-Frankia symbioses

An open flow-through gas system was used to determine the effect of C₂H₂ and elevated O₂ on acetylene reduction activity (ARA) and respiration of the intact, potted root system of Alnus incana (L.) Moench in symbiosis with Frankia Avcll or with a local source of Frankia . Both symbiotic systems responded to C₂H₂ by an immediate plateau range in ARA. The Plateau in ARA was in some cases followed by a decline of less extent than reported for many legumes. A concurrent decline in net respiration of the root system was on average 8% of the CO₂ efflux prior to C₂H₂ introduction.
Respiration of the root systems in both symbioses responded to elevated oxygen levels in the 10 kPa C₂H₂ atmosphere by an increase of up to 17% of the net respiration prior to C₂H₂ introduction in 21 kPa O₂. In contrast, the elevated oxygen levels resulted in an immediate drop in ARA followed by a minor increase to a stable level lower than that at the preceding, lower oxygen tension. The symbiosis with the local Frankia had lost all ARA when the partial pressure of O₂ exceeded 50 kPa, whereas the symbiosis with Avcll still had some activity at 80 kPa O₂. This difference in tolerance of elevated O₂ clearly shows that the oxygen exclusion mechanisms may be controlled by the microsymbiont in Alnus-Frankia symbioses. The symbiotic systems recovered ARA to a similar extent when returned from elevated O₂ levels to 21 kPa O₂.     

Fatty acid and lipid compositions of Conidiobolus

The fatty acid composition of the total lipids from two Conidiobolus species was studied by gas—liquid chromatography. The major fatty acids of C. lamprauges were palmitic acid (C_16:0), oleic acid (C_18:1), linolenic acid (C_18:3), and arachidonic acid (C_20:4). For C. eurymitus , myristic acid (C_14:0), C_16:0, and linoleic acid (C_18:2) were the most abundant acids. The fatty acid composition of C. eurymitus was quite different from that of the Conidiobolus species as mentioned in other reports. The lipid composition of the total lipids of C. lamprauges and C. eurymitus was also studied by thinchrography on quartz rods. Triglycerides and phospholipids were the major components in the two Conidiobolus species.     

Diversity, biogeography, and photosynthetic pathways of Argusia and Heliotropium (Boraginaceae) in South-West Asia with an analysis of phytogeographical units

South-West and Central Asia are major centres of diversity in the genus Heliotropium . On the basis of detailed taxonomic studies and information gathered from the literature, a synopsis of 61 known species of Heliotropium and two species of Arguzia in the area is given. Iran, with 32 species and 14 (sub)endemic species, has the highest diversity. The photosynthetic pathways of 42 taxa were determined using the isotope composition method. Except for H. marifolium Retz s.l. and H. rariflorum Stocks, all remaining species analysed showed δ¹³C values characteristic for C₃ photosynthesis. Evidently, by contrast with the families Chenopodiaceae and Polygonaceae, the Irano-Turanian area is not an authochthonous region of developing C₄ species in Heliotropium . The distribution maps of 57 taxa are provided and their biogeographical importance is discussed in order to elucidate the distribution patterns in South-West Asia. In the Irano-Turanian region, the Irano-Anatolian province of Zohary, which extends from central Anatolia to the western Himalaya, is a very large and vaguely defined phytochorion that should be split into smaller units. The consideration of southern Iran and adjacent Pakistan as part of the Sudanian or Saharo-Sindian regions ( sensu either Zohary or Léonard) cannot be accepted, because most endemic species in this area are either typical Irano-Turanian or isolated relicts. Furthermore, it is concluded that the Saharo-Sindian flora is not an autochthonous flora; most species are of transgressive origin from the surrounding phytochoria. Finally, a new species, Heliotropium ziegleri Akhani, is described from Iran.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society, 2007, 155 , 401–425.     

Seasonal differences in photosynthesis between the C3 and C4 subspecies of Alloteropsis semialata are offset by frost and drought

The regional abundance of C₄ grasses is strongly controlled by temperature, however, the role of precipitation is less clear. Progress in elucidating the direct effects of photosynthetic pathway on these climate relationships is hindered by the significant genetic divergence between major C₃ and C₄ grass lineages. We addressed this problem by examining seasonal climate responses of photosynthesis in Alloteropsis semialata , a unique grass species with both C₃ and C₄ subspecies. Experimental manipulation of rainfall in a common garden in South Africa tested the hypotheses that: (1) photosynthesis is greater in the C₄ than C₃ subspecies under high summer temperatures, but this pattern is reversed at low winter temperatures; and (2) the photosynthetic advantage of C₄ plants is enhanced during drought events. Measurements of leaf gas exchange over 2 years showed a significant photosynthetic advantage for the C₄ subspecies under irrigated conditions from spring through autumn. However, the C₄ leaves were killed by winter frost, while photosynthesis continued in the C₃ plants. Unexpectedly, the C₄ subspecies also lost its photosynthetic advantage during natural drought events, despite greater water-use efficiency under irrigated conditions. This study highlights previously unrecognized roles for climatic extremes in determining the ecological success of C₃ and C₄ grasses.     

Key role of teichoic acids on aflatoxin B1 binding by probiotic bacteria

Aims:  To assess the ability of five probiotic bacteria to bind aflatoxin B₁ and to determine the key role of teichoic acids in the binding mechanism.
Methods and Results:  The strains were incubated in aqueous solutions containing aflatoxin B₁ (AFB₁). The amount of free toxin was quantified by HPLC. Stability of the bacteria–aflatoxin complex was evaluated by repeated washes with buffer. In order to understand the binding process, protoplasts, spheroplasts and cell wall components of two strains were analysed to assess their capacity to bind AFB₁. Additionally, the role of teichoic acids in the AFB₁ binding process was assessed. Lactobacillus reuteri strain NRRL14171 and Lactobacillus casei strain Shirota were the most efficient strains for binding AFB₁. The stability of the AFB₁–bacteria complex appears to be related to the binding ability of a particular strain; AFB₁ binding was also pH-dependent. Our results suggest that teichoic acids could be responsible for this ability.
Conclusions:  Our results provide information concerning AFB₁ binding by previously untested strains, leading to enhanced understanding of the mechanism by which probiotic bacteria bind AFB₁.
Significance and Impact of the Study:  Our results support the suggestion that some probiotic bacteria could prevent absorption of aflatoxin from the gastrointestinal tract.     

Response of phenolic metabolism to the application of carbendazim plus boron in tobacco

In view of the essential role of phenolic compounds in the development of pathogen resistance in plants, and given the influence that fungicides and boron (B) exert over phenolic metabolism, the aim of the present study was to determine the individual effect of the application of a fungicide, as well as to determine the joint effect of the fungicide and B on the metabolism of phenolic compounds in tobacco plants ( Nicotiana tabacum L. cv. Tennessee 86). The fungicide applied was carbendazim (carb), a preventative fungicide, with a purity of 100% at a concentration of 2.6 m M . Boron was applied in the form of H₃BO₃ at: 1.6 m M (B₁), 4 m M (B₂), 8 m M (B₃), 16 m M (B₄), 32 m M (B₅), or 64 m M (B₆). In all, there were eight treatments: one without carb and without B (control), one with only carb, and six combinations of carb with each concentration of B. The results indicated that the foliar application with carb alone led to increases in phenylalanine ammonia-lyase (PAL; EC 4.3.1.5) activity and a foliar accumulation of phenols. This effect of the carb alone could signify an additional tolerance mechanism to pathogenic infection, given the participation of phenolic compounds in the lignification of plant cell walls. The joint application of carb and B increased both the biosynthesis and the oxidation of the phenolic compounds, especially in carb plus B₃, while the application of carb plus B₅ or carb plus B₆ reduced these processes as well as the foliar biomass.     

Carbon isotope ratios of plants and occurrences of C4 species under different soil moisture regimes in arid region of Northwest China

Carbon isotope ratio of leaf dry matter, δ ¹³C, was measured on species occurring within Baiyin desert community, consisting of valley, slope and ridge microhabitats, and within Shandan desert community, consisting of Gobi desert and seasonal flooded creek microhabitats, in Northwest China. δ ¹³C of C₃ species increased with a decrease in soil water availability, suggesting that water-use efficiency (WUE) increased with decreasing soil moisture, whereas for all C₄ species, δ ¹³C tended to decrease with decreasing soil water availability, suggesting that WUE also increased with decreasing soil moisture. Above results indicated that water-use pattern was conservative under drought for C₄ and C₃ plants. In this present study, C₄ species' occurrences within different microhabitats were investigated and C₄ plants were observed to be absent and/or scarce within relatively lower soil moisture microhabitats, whereas they occurred and/or even had a high abundance within relatively higher soil moisture microhabitats, suggesting limited moisture available was a key factor of limiting C₄ distribution in arid region of Northwest China.     

Enhanced degradation of petrol (Slovene diesel) in an aqueous system by immobilized Pseudomonas fluorescens

The rate of degradation of n -alkanes C₁₂-C₁₈, in petrol (Slovene diesel) in an aqueous system, by free and immobilized Pseudomonas fluorescens in shaking flasks was investigated. Cells were immobilized to a biosupport, Biofix, and a biosorbant, Drizit. Analysis of cellular growth of the free and immobilized bacteria over 8 d of incubation with diesel as the sole carbon source, showed a reduction in the lag phase in the immobilized cultures in comparison to the free system. The free system degraded 52·3% of C₁₂ and 11·6% of C₁₃, but C₁₄-C₁₈ were not degraded. In comparison to the free system and diesel which had not been exposed to experimental conditions (unexposed), the immobilized systems degraded significantly more of C₁₃-C₁₈. Biofix-immobilized cells degraded 14·8% of C₁₂ and an average of 53·5% of C₁₃-C₁₈. Drizit-immobilized cells degraded 24·5% of C₁₂, 52·4% of C₁₃ and an average of 91·2% of C₁₄-C₁₈. This study shows the successful use of immobilized bacteria technology to enhance the degradation of diesel in an aqueous system.     

Degradation of crude oil by Acinetobacter calcoaceticus and Alcaligenes odorans

Two types of Indian crude oil (Bombay High and Gujarat) were tested for their biodegradability by Acinetobacter calcoaceticus and Alcaligenes odorans. Acinetobacter calcoaceticus S30 and Alc. odorans P20 degraded Bombay High crude oil by 50% and 45%, while only 29% and 37% of Gujarat crude oil (heavy crude oil) was degraded by these isolates, respectively. Acinetobacter calcoaceticus and Alc. odorans in combination deraded 58% and 40% of Bombay High and Gujarat crude oils, respectively, which were significantly higher than that of by individual cultures. Acinetobacter calcoaceticus S30 degraded more of the alkanes fraction than the aromatics fraction of both crude oils. GC fingerprinting of alkane fraction showed major degradation of heptadecane (C₁₇), octadecane (C₁₈), nonadecane (C₁₉), eicosane (C₂₀), docosane (C₂₂), tricosane (C₂₃) and tetracosane (C₂₄) of crude oil, while the Alc. odorans P20 degraded alkanes and aromatics equally. The asphaltenic component increased in both types of crude oil after biodegradation. The two strains grew very well on n -alkane up to C₃₃ as well as on pristane (branched-chain alkane) but could not grow on cycloalkanes. Acinetobacter calcoaceticus S30 could not grow on pure polycyclic aromatic hydrocarbon (PAH) compounds except naphthalene but Alc. odorans P20 could grow on anthracene, phenanthrene, dibenzothiophene, fluorene, fluoranthene, pyrene and chrysene.     

Evidence for the occurrence of the alternative, vanadium-containing nitrogenase in the cyanobacterium Anabaena variabilis

Abstract Anabaena variabilis can be grown with dependence on either molybdenum (Mo) or vanadium (V) in the medium with essentially the same growth rates. Vanadium cultures reduce C₂H₂ to C₂H₄ and partly (to 2–3%) to C₂H₆. These C₂H₄ and C₂H₆ formations can be shown to be strictly light dependent, proving that the gases are formed by the cyanobacterium. C₂H₄ and C₂H₆ productions are accompanied by a H₂ formation which is much higher than in Mo cultures. Maximal C₂H₂-formation rates are 2/3 lower in V-grown cells compared to Mo control cultures. This is the first demonstration of a light-dependent ethane formation and of the occurrence of the alternative nitrogenase in any phototroph.