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1.
从柴油污染的海水样品中分离高效柴油降解细菌,分析菌株对柴油的降解能力及降解酶基因,为海洋柴油污染的生物修复奠定基础。选取浙江定海港柴油污染的海水样品,进行降解菌的富集培养;采用常规方法分离筛选高效柴油降解菌。利用革兰氏染色、形态学观察、生理生化鉴定及16S rDNA分析等方法对降解菌株进行种属鉴定。采用紫外吸收法测定菌株对柴油的降解率。采用PCR方法、核酸序列测定和比对,对其降解酶基因进行扩增分析。筛选出一株高效降解菌,形态学观察及生理生化鉴定初步确定为不动杆菌。16S rDNA序列分析及比对结果表明,其16S rDNA序列与威尼斯不动杆菌(Acinetobacter venetianus)属的序列同源性达到99.7%,命名为不动杆菌W3(Acinetobactersp.W3),该菌对柴油的7 d降解率达到84.7%。PCR方法从Acinetobactersp.W3菌株中的基因组DNA和质粒DNA上扩增到了大小为540 bp的烷烃羟化酶基因alkB和864 bp的CYP153A部分DNA片段,分别与Acinetobacter venetianus1-D-2的alkB和Acinetobactersp.OC4、Acinetobactersp.EB104的CYP153具有99%和98%的同源性。从定海港口柴油污染海水分离得到一株高效柴油降解菌Acinetobactersp.W3,该菌属于不动杆菌属,含有烷烃降解酶基因,能高效降解柴油污染物,有望应用于海水柴油污染的生物修复。  相似文献   

2.
Alcanivorax is an alkane-degrading marine bacterium which propagates and becomes predominant in crude-oil-containing seawater when nitrogen and phosphorus nutrients are supplemented. In order to understand why Alcanivorax overcomes other bacteria under such cultural conditions, competition experiments between Alcanivorax indigenous to seawater and the exogenous alkane-degrading marine bacterium, Acinetobacter venetianus strain T4, were conducted. When oil-containing seawater supplemented with nitrogen and phosphorus nutrients was inoculated with A. venetianus strain T4, this bacterium was the dominant population at the early stage of culture. However, its density began to decrease after day 6, and Alcanivorax predominated in the culture after day 20. The crude-oil-degrading profiles of both bacteria were therefore investigated. Alcanivorax borkumensis strain ST-T1 isolated from the Sea of Japan exhibited higher ability to degrade branched alkanes (pristane and phytane) than A. venetianus strain T4. It seems that this higher ability of Alcanivorax to degrade branched alkanes allowed this bacterium to predominate in oil-containing seawater. It is known that some marine zooplanktons produce pristane and Alcanivorax may play a major role in the biodegradation of pristane in seawater.  相似文献   

3.
Five dimorphic yeast strains were isolated from rotting lime fruits in Borneo. The sequences of the D1/D2 domains of the 26S rRNA genes, the internal transcribed spacer (ITS) chromosomal regions and the 18S rRNA genes were identical in the isolates and differed from the corresponding sequences of all known yeast species. Based on the sequence differences (12-15% in the D1/D2 domain) from the closest relatives and the different pattern of taxonomic traits, the new isolates are assigned the status of a new species, for which the name Candida citri sp. nov. is proposed. Its type strain is 11-469(T) , which has been deposited in Centralbureau voor Schimmelcultures (Utrecht, the Netherlands) as CBS 11858(T) , Culture Collection of Yeasts (Bratislava, Slovakia) as CCY 29-181-1(T) and the National Collection of Agricultural and Industrial Microorganisms (Budapest, Hungary) as NCAIM Y.01978(T) . MycoBank number: MB 519100. The GenBank accession numbers for nucleotide sequences of its D1/D2 domain, ITS and 18S regions are HM803241, HM803242 and HM803243, respectively. Candida citri produces invasive mycelium composed of true septate hyphae that grow towards nutrient-rich parts of the medium and develop large vacuoles at the nongrowing ends of their cells. The hyphae produce blastoconidia, which can establish satellite yeast colonies in the invaded solid substrate.  相似文献   

4.
We report the draft genome sequence of Acinetobacter venetianus strain RAG-1(T), which is able to degrade hydrocarbons and to synthesize a powerful biosurfactant (emulsan) that can be employed for oil removal and as an adjuvant for vaccine delivery. The genome sequence of A. venetianus RAG-1(T) might be useful for bioremediation and/or clinical purposes.  相似文献   

5.
The behavior of the soil bacterium Acinetobacter sp. BD413 was monitored in Ralstonia solanacearum-infected and non-infected tomato plants after direct injection into the stem or natural infection by roots. In healthy plants, Acinetobacter sp. BD413 failed to colonize plant tissue. In plants infected simultaneously by the pathogen R. solanacearum,the Acinetobacter population increased linearly to about 3.1 x 10(7) cells per gram plant material and was maintained at a high level until the death of the plant. Moreover, Acinetobacter sp. BD413 was found to develop a competent state when multiplying in planta, indicating it could possibly be transformed by bacterial or plant DNA.  相似文献   

6.
Genetic systems development in the clostridia   总被引:1,自引:0,他引:1  
Abstract: This review describes recent developments in the genetic manipulation of the solventogenic clostridia, Clostridium acetobutylicum and C. beijerinckii . It is to be noted that our laboratory stock of C. acetobutylicum ATCC 824, which was obtained from the American Type Culture Collection, has recently been re-identified as C. beijerinckii NCIMB 8052 based on DNA similarity studies using the S1 nuclease method (personal communication, Dr. Jiann-Shin Chen, Virginia Polytechnic Institute and State University). Reference to our laboratory 824 culture has been changed to C. beijerinckii NCIMB 8052 throughout this paper in order to be consistent with this finding. The focus of this review specifically involves the characterization of an M13-like genetic system for the clostridia based on the pCAK1 phagemid, as well as preliminary work on development of a plasmid-based vector based on the indigenous pDM11 plasmid recovered from C. acetobutylicum NCIB 6443. The construction of a C. beijerinckii strain with amplified endoglucanase activity was achieved by inserting the engB gene from C. cellulovorans into C. beijerinckii . The successful expression of a heterologous engB gene from C. cellulovorans in C. beijerinckii NCIMB 8052 has important industrial significance for the eventual utilization of cellulose by this acetone-butanol-ethanol fermentation microorganism.  相似文献   

7.
Sex determination and hatching success in sea turtles is temperature dependent and as a result global warming poses a threat to sea turtles. Warmer sand temperatures may skew sea turtle population′s sex ratios towards predominantly females and decrease hatching success. Therefore, understanding the rates at which sand temperatures are likely to increase as climate change progresses is warranted. We recorded sand temperature and used historical sea surface and air temperature to model past and to predict future sand temperature under various scenarios of global warming at key sea turtle nesting grounds (n = 7) used by the northern Great Barrier Reef (nGBR) green turtle, Chelonia mydas, population. Reconstructed temperatures from 1990 to the present suggest that sand temperatures at the nesting sites studied have not changed significantly during the last 18 years. Current thermal profile at the nesting grounds suggests a bias towards female hatchling production into this population. Inter-beach thermal variance was observed at some nesting grounds with open areas in the sand dune at northern facing beaches having the warmest incubating environments. Our model projections suggest that a near complete feminization of hatchling output into this population will occur by 2070 under an extreme scenario of climate change (A1T emission scenario). Importantly, we found that some nesting grounds will still produce male hatchlings, under the most extreme scenario of climate change, this finding differs from predictions for other locations. Information from this study provides a better understanding of possible future changes in hatching success and sex ratios at each site and identifies important male producing regions. This allowed us to suggest strategies that can be used at a local scale to offset some of the impacts of warmer incubating temperatures to sea turtles.  相似文献   

8.
There are major concerns about the ecological impact of extreme weather events. In the oceans, marine heatwaves (MHWs) are an increasing threat causing, for example, recent devastation to coral reefs around the world. We show that these impacts extend to adjacent terrestrial systems and could negatively affect the breeding of endangered species. We demonstrate that during an MHW that resulted in major coral bleaching and mortality in a large, remote marine protected area, anomalously warm temperatures also occurred on sea turtle nesting beaches. Granger causality testing showed that variations in sea surface temperature strongly influenced sand temperatures on beaches. We estimate that the warm conditions on both coral reefs and sandy beaches during the MHW were unprecedented in the last 70 years. Model predictions suggest that the most extreme female-biased hatchling sex ratio and the lowest hatchling survival in nests in the last 70 years both occurred during the heatwave. Our work shows that predicted increases in the frequency and intensity of MHWs will likely have growing impacts on sea turtle nesting beaches as well as other terrestrial coastal environments.  相似文献   

9.
Offspring sex ratio is an important demographic parameter and, given its determination by incubation temperature in sea turtles, might be a key factor for their conservation under climate warming. An appealing approach to estimate hatchling sex ratios is to measure sand temperatures at nest depth and deduce hatchling sex ratios from a beforehand-established relationship of hatchling sex ratio and sand temperature. Such estimates will only be accurate though if metabolic heat produced by the embryos is considered. Judging whether metabolic heating has a potential effect on hatchling sex ratios without actually measuring temperature within clutches would greatly facilitate monitoring protocols. We tested for a relationship between the amount of metabolic heating and the number of developed embryos as well as clutch size in the largest known loggerhead sea turtle (Caretta caretta) population of the Mediterranean on Zakynthos (Greece). Temperatures were measured within 20 nests as well as at a reference site in the sand at nest depth. Metabolic heating was detected, but only during the last third of the incubation period did nests heat up considerably (1.6 °C on average) above the temperature of the surrounding sand. During the middle third of incubation, when sex is determined, the amount of metabolic heating was negligible. The amount of metabolic heating during the last third of the incubation duration was significantly correlated to the number of offspring developed to at least about 75% of incubation duration. This factor explained nearly 50% of variation in metabolic heating. Metabolic heating was also significantly correlated to clutch size. Given that clutch size within the Mediterranean is largest in Zakynthos loggerheads, we conclude that metabolic heating can be ignored in the estimate of hatchling sex ratios in Mediterranean loggerhead populations. These results thus provide the basis for a feasible monitoring of hatchling sex ratios in the loggerhead sea turtle in the Mediterranean.  相似文献   

10.
This study reports the discovery of the exclusive predation of sea turtle hatchlings by several juvenile blacktip reef sharks (Carcharhinus melanopterus) in Chagar Hutang bay on Redang Island, Malaysia, in the South China Sea. Three dead specimens of C. melanopterus were retrieved from ghost nets, and the entire digestive tracts of these sharks solely contained the partially digested bodies of sea turtle hatchlings, with no evidence of the remains of any other prey. Thus, juvenile C. melanopterus may opportunistically feed primarily on turtle hatchlings during times when hatchling abundance is high.  相似文献   

11.
Animals living in tropical regions may be at increased risk from climate change because current temperatures at these locations already approach critical physiological thresholds. Relatively small temperature increases could cause animals to exceed these thresholds more often, resulting in substantial fitness costs or even death. Oviparous species could be especially vulnerable because the maximum thermal tolerances of incubating embryos is often lower than adult counterparts, and in many species mothers abandon the eggs after oviposition, rendering them immobile and thus unable to avoid extreme temperatures. As a consequence, the effects of climate change might become evident earlier and be more devastating for hatchling production in the tropics. Loggerhead sea turtles (Caretta caretta) have the widest nesting range of any living reptile, spanning temperate to tropical latitudes in both hemispheres. Currently, loggerhead sea turtle populations in the tropics produce nearly 30% fewer hatchlings per nest than temperate populations. Strong correlations between empirical hatching success and habitat quality allowed global predictions of the spatiotemporal impacts of climate change on this fitness trait. Under climate change, many sea turtle populations nesting in tropical environments are predicted to experience severe reductions in hatchling production, whereas hatching success in many temperate populations could remain unchanged or even increase with rising temperatures. Some populations could show very complex responses to climate change, with higher relative hatchling production as temperatures begin to increase, followed by declines as critical physiological thresholds are exceeded more frequently. Predicting when, where, and how climate change could impact the reproductive output of local populations is crucial for anticipating how a warming world will influence population size, growth, and stability.  相似文献   

12.
Oceanic dispersal characterizes the early juvenile life-stages of numerous marine species of conservation concern. This early stage may be a ‘critical period’ for many species, playing an overriding role in population dynamics. Often, relatively little information is available on their distribution during this period, limiting the effectiveness of efforts to understand environmental and anthropogenic impacts on these species. Here we present a simple model to predict annual variation in the distribution and abundance of oceanic-stage juvenile sea turtles based on species’ reproductive output, movement and mortality. We simulated dispersal of 25 cohorts (1993–2017) of oceanic-stage juveniles by tracking the movements of virtual hatchling sea turtles released in a hindcast ocean circulation model. We then used estimates of annual hatchling production from Kemp's ridley Lepidochelys kempii (n = 3), green Chelonia mydas (n = 8) and loggerhead Caretta caretta (n = 5) nesting areas in the northwestern Atlantic (inclusive of the Gulf of Mexico, Caribbean Sea and eastern seaboard of the U.S.) and their stage-specific mortality rates to weight dispersal predictions. The model's predictions indicate spatial heterogeneity in turtle distribution across their marine range, identify locations of increasing turtle abundance (notably along the U.S. coast), and provide valuable context for temporal variation in the stranding of young sea turtles across the Gulf of Mexico. Further effort to collect demographic, distribution and behavioral data that refine, complement and extend the utility of this modeling approach for sea turtles and other dispersive marine taxa is warranted. Finally, generating these spatially-explicit predictions of turtle abundance required extensive international collaboration among scientists; our findings indicate that continued conservation of these sea turtle populations and the management of the numerous anthropogenic activities that operate in the northwestern Atlantic Ocean will require similar international coordination.  相似文献   

13.
Measuring the metabolic of sea turtles is fundamental to understanding their ecology yet the presently available methods are limited. Accelerometry is a relatively new technique for estimating metabolic rate that has shown promise with a number of species but its utility with air-breathing divers is not yet established. The present study undertakes laboratory experiments to investigate whether rate of oxygen uptake ( o 2) at the surface in active sub-adult green turtles Chelonia mydas and hatchling loggerhead turtles Caretta caretta correlates with overall dynamic body acceleration (ODBA), a derivative of acceleration used as a proxy for metabolic rate. Six green turtles (25–44 kg) and two loggerhead turtles (20 g) were instrumented with tri-axial acceleration logging devices and placed singly into a respirometry chamber. The green turtles were able to submerge freely within a 1.5 m deep tank and the loggerhead turtles were tethered in water 16 cm deep so that they swam at the surface. A significant prediction equation for mean o 2 over an hour in a green turtle from measures of ODBA and mean flipper length (R2 = 0.56) returned a mean estimate error across turtles of 8.0%. The range of temperatures used in the green turtle experiments (22–30°C) had only a small effect on o 2. A o 2-ODBA equation for the loggerhead hatchling data was also significant (R2 = 0.67). Together these data indicate the potential of the accelerometry technique for estimating energy expenditure in sea turtles, which may have important applications in sea turtle diving ecology, and also in conservation such as assessing turtle survival times when trapped underwater in fishing nets.  相似文献   

14.
Squamate reptiles rely heavily on visual and chemical cues to detect their prey, so we expected yellow‐spotted goannas (Varanus panoptes) which are predators of sea turtle nests on mainland beaches in northern Australia would use these cues to find sea turtle nests. Ghost crabs (Ocypode ceratophthalmus and Ocypode cordimanus) are also common on Australian sea turtle nesting beaches and frequently burrow into sea turtle nests. However, the potential for ghost crab burrowing activity at sea turtle nests to signal the location of a nest to goannas has not been investigated. Here, we used camera traps and presence of tracks at nests to record goanna activity around selected nests during the incubation period and 10 days after hatchling turtles emerged from their nests. We also recorded the number of ghost crab burrows around nests to evaluate ghost crab activity. Our results indicated that nest discovery by goannas was independent of nest age, but that the nest visitation rate of goannas and crabs increased significantly after a nest had been opened by a goanna or after hatchlings had emerged from the nest. There was no apparent connection between ghost crab burrows into a nest and the likelihood of that nest being predated by goannas.  相似文献   

15.
The type strain of Listeria monocytogenes differs from wild-type L. monocytogenes strains in more characteristics than just the previously reported deficiency in hemolytic activity and virulence in the murine infection model. The type strain from the American Type Culture Collection (strain ATCC 15313) produces lecithinase, is hemolytic on rabbit (but not sheep) blood agar, lacks motility, and shows limited cytopathogenic effects on Caco-2 monolayers, whereas the type strain from the Special Listeria Culture Collection (strain SLCC 53) is unable to produce lecithinase, is nonhemolytic on rabbit or sheep blood agar, is motile, and shows no cytopathogenic effects on Caco-2 monolayers.  相似文献   

16.
Recent increases in global temperatures have affected the phenology and survival of many species of plants and animals. We investigated a case study of the effects of potential climate change on a thermally sensitive species, the loggerhead sea turtle, at a breeding location at the northerly extent of the range of regular nesting in the United States. In addition to the physical limits imposed by temperature on this ectothermic species, sea turtle primary sex ratio is determined by the temperature experienced by eggs during the middle third of incubation. We recorded sand temperatures and used historical air temperatures (ATs) at Bald Head Island, NC, to examine past and predict future sex ratios under scenarios of warming. There were no significant temporal trends in primary sex ratio evident in recent years and estimated mean annual sex ratio was 58% female. Similarly, there were no temporal trends in phenology but earlier nesting and longer nesting seasons were correlated with warmer sea surface temperature. We modelled the effects of incremental increases in mean AT of up to 7.5°C, the maximum predicted increase under modelled scenarios, which would lead to 100% female hatchling production and lethally high incubation temperatures, causing reduction in hatchling production. Populations of turtles in more southern parts of the United States are currently highly female biased and are likely to become ultra‐biased with as little as 1°C of warming and experience extreme levels of mortality if warming exceeds 3°C. The lack of a demonstrable increase in AT in North Carolina in recent decades coupled with primary sex ratios that are not highly biased means that the male offspring from North Carolina could play an increasingly important role in the future viability of the loggerhead turtle in the Western Atlantic.  相似文献   

17.
The study of temperature‐dependent sex determination (TSD) in vertebrates has attracted major scientific interest. Recently, concerns for species with TSD in a warming world have increased because imbalanced sex ratios could potentially threaten population viability. In contrast, relatively little attention has been given to the direct effects of increased temperatures on successful embryonic development. Using 6603 days of sand temperature data recorded across 6 years at a globally important loggerhead sea turtle rookery—the Cape Verde Islands—we show the effects of warming incubation temperatures on the survival of hatchlings in nests. Incorporating published data (n = 110 data points for three species across 12 sites globally), we show the generality of relationships between hatchling mortality and incubation temperature and hence the broad applicability of our findings to sea turtles in general. We use a mechanistic approach supplemented by empirical data to consider the linked effects of warming temperatures on hatchling output and on sex ratios for these species that exhibit TSD. Our results show that higher temperatures increase the natural growth rate of the population as more females are produced. As a result, we project that numbers of nests at this globally important site will increase by approximately 30% by the year 2100. However, as incubation temperatures near lethal levels, the natural growth rate of the population decreases and the long‐term survival of this turtle population is threatened. Our results highlight concerns for species with TSD in a warming world and underline the need for research to extend from a focus on temperature‐dependent sex determination to a focus on temperature‐linked hatchling mortalities.  相似文献   

18.
AIMS: The need for biocompatible, biodegradable, and versatile biopolymers permeates many fields including environmental and food technology. The goal of the study presented here is to establish the utility of agricultural oils as an inexpensive carbon source to produce materials useful for biomedical materials and offer positive attributes in terms of green chemistry. METHODS AND RESULTS: Structural variants of the complex acylated polysaccharide, emulsan, secreted from Acinetobacter venetianus RAG-1, were biosynthesized in cultures supplemented with agricultural feedstocks to examine the feasibility of conversion of these substrates into value-added biopolymers. Acinetobacter venetianus produced chemically and biologically distinct emulsan variants in culture on soy molasses and tallow oil. These variants possess significant biological function, including macrophage activation and adjuvant activity, in similar range to that observed for the standard emulsan formed on ethanol-fed A. venetianus. CONCLUSIONS: The results indicate that this novel family of biopolymers can be produced in significant quantities from the readily available renewable agricultural feedstocks and the resulting structures and functions can be correlated to the chemistry of these feedstocks. SIGNIFICANCE AND IMPACT OF THE STUDY: The significant quantities of agricultural oils produced annually represent an untapped source for bioconversion to valuable products. The results of this study confirm that the important polymer emulsan can be synthesized from this inexpensive carbon source.  相似文献   

19.
Marine turtle fibropapillomatosis is associated with chelonid fibropapilloma-associated herpesvirus (C-FP-HV) and commonly affects juvenile green turtles (Chelonia mydas) in neritic (nearshore) habitats. Green turtles have a complex life history, characterized by shifts in trophic level as well as habitat during ontogeny. Thus, several hypotheses can be proposed for when turtles become infected with C-FP-HV. They may acquire the virus at an early stage in the life cycle, including prenatal, hatchling, or the posthatchling pelagic stages. Alternatively, they may become infected later in life after they emigrate from the open ocean to neritic habitats. Each hypothesis generates predictions about the spatial distribution of genetic variants of C-FP-HV among nearshore sites within a region. Sequencing of polymerase chain reaction-amplified viral DNA from fibropapillomas of individual turtles was used to genotype the viral variants present in marine turtles from different coastal areas in Florida. We found four distinct virus variants (A, B, C, and D), two of which (A and C) were present in multiple turtle species. Green turtles in Florida were infected with variants A, B, and C. Variant A was found in green turtles from all three areas. Outside the Indian River Lagoon, variant A was most commonly detected and was found in >94% of diseased green turtles and 70% of loggerhead sea turtles (Caretta caretta) in the Florida Bay/Florida Keys. However, in the Indian River Lagoon, variant B was found in >94% of affected green turtles. Variant B was not detected outside of the Indian River system. Chi-square analysis strongly supported (P<0.001) an association between viral variant distribution in green turtles and location. On the basis of the assumption that juvenile green turtles found in Florida's west-central coast, Florida Keys, and Indian River Lagoon areas represented recruits from a mixed pelagic population, we expected that the distribution of viral variants in these turtles would be relatively homogeneous among locations; this would correspond to infection in the earlier phases of their life cycle. The heterogeneous distribution of viral variants in green turtle tumors from different Florida coastal locations strongly supports the hypothesis that, during epizootics, turtles are infected with specific C-FP-HV variants after they arrive as juveniles in neritic habitats. The conclusion that C-FP-HV is acquired after turtles recruit to nearshore habitats should help focus further research efforts on understanding the mechanisms of transmission and raises the possibility that the effect of fibropapillomatosis on turtle populations might be reduced by management strategies designed to break the cycle of transmission in these locations.  相似文献   

20.
A bacterium C1010, isolated from the rhizospheres of cucumbers in fields in Korea, degraded the microbial quorum-sensing molecules, hexanoyl homoserine lactone (HHSL), and octadecanoyl homoserine lactone (OHSL). Morphological characteristics and 16S rRNA sequence analysis identified C1010 as Acinetobacter sp. strain C1010. This strain was able to degrade the acyl-homoserine lactones (AHLs) produced by the biocontrol bacterium, Pseudomonas chlororaphis O6, and a phytopathogenic bacterium, Burkholderia glumae. Co-cultivation studies showed that the inactivation of AHLs by C1010 inhibited production of phenazines by P. chlororaphis O6. In virulence tests, the C1010 strain attenuated soft rot symptom caused by Erwinia carotovora ssp. carotovora. We suggest Acinetobacter sp. strain C1010 could be a useful bacterium to manipulate biological functions that are regulated by AHLs in various Gram-negative bacteria.  相似文献   

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