Aquatic Microbial Ecology

Temporal Patterns of Protozooplankton Abundance and Their Food in Ellis Fjord, Princess Elizabeth Land, Eastern Antarctica

by Jonathan Grey

Estuarine, Coastal & Shelf Science 1997

The abundance and biomass of ciliates, dinoflagellates and heterotrophic and phototrophic nanoflagellates were... more The abundance and biomass of ciliates, dinoflagellates and heterotrophic and phototrophic nanoflagellates were determined at three sites along an ice-covered Antarctic fjord between January and November 1993. The water column showed little in the way of temperature and salinity gradients during the study period. In general, the protozooplankton exhibited a seasonal variation which closely mirrored that of chlorophyll a and bacterioplankton. The fjord mouth, which was affected by the greatest marine influences, consistently had the highest densities of ciliates and the most diverse community, with up to 18 species during the sampling period. Small aloricate ciliates were present throughout the year with Strobilidium spp. being dominant during the winter. Larger loricate and aloricate ciliates became more prominent during January and November, along with the autotrophic ciliate Mesodinium rubrum and two mixotrophic species (Strombidium wulffi and a type resembling Tontonia) suggesting evidence of species successions. Data on dinoflagellates were less extensive, but these protists showed greatest species diversity in the middle reaches of the fjord. A total of 13 species of dinoflagellate was recorded.
Ciliates made a significant contribution to the biomass of the microbial community in summer, particularly in the middle and at the seaward end of the fjord. In winter, heterotrophic flagellates (HNAN) and phototrophic nanoflagellates (PNAN) were the dominant component of protistan biomass. In terms of percentage contribution to the microbial carbon pool, bacteria dominated during winter and spring. To the authors’ knowledge, this is the first seasonal study of an Antarctic fjord. The Ellis Fjord is very unproductive compared to lower latitude systems, and supports low biomass of phytoplankton and microbial plankton during most of the year. This relates to severe climatic and seasonal conditions, and the lack of allochthonous carbon inputs to the system. Thus, high latitude estuaries may differ significantly from lower latitude systems, which generally rank among the most productive aquatic systems in the world.

Benthic–-pelagic coupling in the population dynamics of the harmful cyanobacterium Microcystis

by Klaus Joehnk

Verspagen, J.M.H., Snelder, E.O.F.M., Visser, P.M., Jöhnk, K.D., Ibelings, B.W., Mur, L.R., Huisman, J., 2005. Benthic - pelagic coupling in the population dynamics of the cyanobacterium Microcystis. Freshwater Biology 50: 854-867.

Phylogenetic clustering increases with elevation for microbes

by jianjun wang

Jianjun Wang, Janne Soininen, Jizheng He, Ji Shen, Phylogenetic clustering increases with elevation in microbes, Environmental Microbiology Reports 4: 217-226.

Summary
Although phylogenetic approaches are useful for providing insights into the processes underlying... more Summary
Although phylogenetic approaches are useful for providing insights into the processes underlying biodiversity patterns, the studies of microbial phylogenetic relatedness are rare, especially for elevational gradients. Using high-throughput pyrosequencing, we examined the biodiversity patterns for biofilm bacterial communities that were scraped from stream stones along an elevational gradient from 1820 to 4050 m in China. The patterns of bacterial species richness and phylogenetic diversity were hollow towards higher elevations. The bacterial communities consisted of closer relatives than expected and displayed increasing terminal phylogenetic clustering towards mountain top. The increasing phylogenetic clustering with elevation contrasts reports for macroorganisms that revealed phylogenetic overdispersion at low or intermediate elevations. Because water temperature showed the strongest correlation with phylogenetic relatedness (r2 = 0.516), the elevational pattern in the bacterial phylogenetic structure indicated that environmental filtering possibly due to lower temperature or more frequent temperature fluctuations increased towards higher elevations. Evidence supporting the environmental filtering on bacteria was also reflected by the orderly succession in the relative abundance of different bacterial phyla along the elevational gradient and in the high evenness of bacterial taxa at higher elevations. Overall, our results indicated that ecological processes possibly related to temperature may play a dominant role in structuring bacterial biodiversity along the elevational gradient.

Keywords: Bacteria, Elevational gradient, Phylogenetic diversity, Phylogenetic relatedness, Species diversity pattern, Streams

mean nearest taxon distances: MNTD
mean nearest neighbor distance: MNND
standardized effect size of mean nearest taxon distances: ses.MNTD
nearest taxon index: NTI

Another new reference:
Stegen, J.C., Lin, X., Konopka, A.E., and Fredrickson, J.K. (2012) Stochastic and deterministic assembly processes in subsurface microbial communities. ISME J. In press.

Microbiological study of the Special Nature Reserve "Gornje Podunavlje" (the Upper Danube Basin)-Monostorski rit (Monostor marsh)

by Alpar Barsi

Do patterns of bacterial diversity along salinity gradients differ from those observed for macroorganisms?

by jianjun wang

Jianjun Wang, Dongmei Yang, Yong Zhang, Ji Shen, Christopher van der Gast, Martin W. Hahn, Qinglong Wu,Do patterns of bacterial diversity along salinity gradients differ from those observed for macroorganisms? Plos One, 6(11):e27597


Similar references:
Parnell JJ, Rompato G, Crowl TA, Weimer BC, Pfrender ME (2011). Phylogenetic distance in Great Salt Lake microbial communities. Aquat Microb Ecol 64: 267-273.

It is widely accepted that biodiversity is lower in more extreme environments. In this study, we sought to determine... more It is widely accepted that biodiversity is lower in more extreme environments. In this study, we sought to determine whether this trend, well documented for macroorganisms, also holds at the microbial level for bacteria. We used denaturing gradient gel electrophoresis (DGGE) with phylum-specific primers to quantify the taxon richness (i.e., the DGGE band numbers) of the bacterioplankton communities of 32 pristine Tibetan lakes that represent a broad salinity range (freshwater to hypersaline). For the lakes investigated, salinity was found to be the environmental variable with the strongest influence on the bacterial community composition. We found that the bacterial taxon richness in freshwater habitats increased with increasing salinity up to a value of 1‰. In saline systems (systems with > 1‰ salinity), the expected decrease of taxon richness along a gradient of further increasing salinity was not observed. These patterns were consistently observed for two sets of samples taken in two different years. A comparison of 16S rRNA gene clone libraries revealed that the bacterial community of the lake with the highest salinity was characterized by a higher recent accelerated diversification than the community of a freshwater lake, whereas the phylogenetic diversity in the hypersaline lake was lower than that in the freshwater lake. These results suggest that different evolutionary forces may act on bacterial populations in freshwater and hypersaline lakes on the Tibetan Plateau, potentially resulting in different community structures and diversity patterns.

Keywords: Bacteria, taxon richness, salinity gradient, lake

Transcriptional regulation of the S‐layer protein type I secretion system in Caulobacter crescentus

by Assaf Levi

Antagonistic interactions between filamentous heterotrophs and the cyanobacterium Nostoc muscorum

by Miro Svercel

Background

Little is known about interactions between filamentous heterotrophs and filamentous... more Background

Little is known about interactions between filamentous heterotrophs and filamentous cyanobacteria. Here, interactions between the filamentous heterotrophic bacteria Fibrella aestuarina (strain BUZ 2) and Fibrisoma limi (BUZ 3) with an axenic strain of the autotrophic filamentous cyanobacterium Nostoc muscorum (SAG 25.82 ) were studied in mixed cultures under nutrient rich (carbon source present in medium) and poor (carbon source absent in medium) conditions.

Findings

F. aestuarina BUZ 2 significantly reduced the cyanobacterial population whereas F. limi BUZ 3 did not. Physical contact between heterotrophs and autotroph was observed and the cyanobacterial cells showed some level of damage and lysis. Therefore, either contact lysis or entrapment with production of extracellular compounds in close vicinity of host cells could be considered as potential modes of action. The supernatants from pure heterotrophic cultures did not have an effect on Nostoc cultures. However, supernatant from mixed cultures of BUZ 2 and Nostoc had a negative effect on cyanobacterial growth, indicating that the lytic compounds were only produced in the presence of Nostoc. The growth and survival of tested heterotrophs was enhanced by the presence of Nostoc or its metabolites, suggesting that the heterotrophs could utilize the autotrophs and its products as a nutrient source. However, the autotroph could withstand and out-compete the heterotrophs under nutrient poor conditions.

Conclusions

Our results suggest that the nutrients in cultivation media, which boost or reduce the number of heterotrophs, were the important factor influencing the outcome of the interplay between filamentous heterotrophs and autotrophs. For better understanding of these interactions, additional research is needed. In particular, it is necessary to elucidate the mode of action for lysis by heterotrophs, and the possible defense mechanisms of the autotrophs.

Active Methylotrophs In the Sediments of Lonar Lake, a Saline and Alkaline Ecosystem Formed by Meteor Impact

by Rich Boden

ISME Journal

Authors:

Antony CP, Kumaresan D, Ferrando L, Boden R, Moussard H, Scavino AF, Shouche YS, Murrell JC.

Lonar Lake is a unique saline and alkaline ecosystem formed by meteor impact in the Deccan basalts in India around... more Lonar Lake is a unique saline and alkaline ecosystem formed by meteor impact in the Deccan basalts in India around 52,000 years ago. To investigate the role of methylotrophy in the cycling of carbon in this unusual environment, stable-isotope probing (SIP) was carried out using the one-carbon compounds methane, methanol and methylamine. Denaturing gradient gel electrophoresis fingerprinting analyses performed with heavy (13)C-labelled DNA retrieved from sediment microcosms confirmed the enrichment and labelling of active methylotrophic communities. Clone libraries were constructed using PCR primers targeting 16S rRNA genes and functional genes. Methylomicrobium, Methylophaga and Bacillus spp. were identified as the predominant active methylotrophs in methane, methanol and methylamine SIP microcosms, respectively. Absence of mauA gene amplification in the methylamine SIP heavy fraction also indicated that methylamine metabolism in Lonar Lake sediments may not be mediated by the methylamine dehydrogenase enzyme pathway. Many gene sequences retrieved in this study were not affiliated with extant methanotrophs or methylotrophs. These sequences may represent hitherto uncharacterized novel methylotrophs or heterotrophic organisms that may have been cross-feeding on methylotrophic metabolites or biomass. This study represents an essential first step towards understanding the relevance of methylotrophy in the soda lake sediments of an unusual impact crater structure.

Novel Methylotrophic Bacteria Isolated From the River Thames (London, UK)

by Rich Boden

Environmental Microbiology

Authors:

Boden R, Thomas E, Savani P, Kelly DP, Wood AP

Enrichment and elective culture for methylotrophs from sediment of the River Thames in central London yielded a... more Enrichment and elective culture for methylotrophs from sediment of the River Thames in central London yielded a diversity of pure cultures representing several genera of Gram-negative and Gram-positive bacteria, which were mainly of organisms not generally regarded as typically methylotrophic. Substrates leading to successful isolations included methanol, monomethylamine, dimethylamine, trimethylamine, methanesulfonate and dimethylsulfone. Several isolates were studied in detail and shown by their biochemical and morphological properties and 16S rRNA gene sequencing to be Sphingomonas melonis strain ET35, Mycobacterium fluoranthenivorans strain DSQ3, Rhodococcus erythropolis strain DSQ4, Brevibacterium casei strain MSQ5, Klebsiella oxytoca strains MMA/F and MMA/1, Pseudomonas mendocina strain TSQ4, and Flavobacterium sp. strains MSA/1 and MMA/2. The results show that facultative methylotrophy is present across a wide range of Bacteria, suggesting that turnover of diverse C1-compounds is of much greater microbiological and environmental significance than is generally thought. The origins of the genes encoding the enzymes of methylotrophy in diverse heterotrophs need further study, and could further our understanding of the phylogeny and antiquity of methylotrophic systems.

Contrasting patterns in elevational diversity between microorganisms and macroorganisms

by jianjun wang

Wang, Jianjun. Soininen, Janne. Zhang, Yong. Wang, Beixin. Yang, Xiangdong. Shen, Ji. (2011) Contrasting patterns in elevational diversity between microorganisms and macroorganisms. Journal of Biogeography: 38: 595-603. DOI: 10.1111/j.1365-2699.2010.02423.x.

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Similiar references (But different patterns for microbes):
Bahram M, Põlme S, Kõljalg U, Zarre S, Tedersoo L (2011) Regional and local patterns of ectomycorrhizal fungal diversity and community structure along an altitudinal gradient in the Hyrcanian forests of northern Iran. New Phytologist, DOI: 10.1111/j.1469-8137.2011.03927.x
Singh D, Takahashi K, Kim M, Chun J, Adams JM (2011) A Hump-Backed Trend in Bacterial Diversity with Elevation on Mount Fuji, Japan. Microbial Ecology, DOI: 10.1007/s00248-00011-09900-00241.
Fierer, N., McCain, C., Meir, P., Zimmerman, M., Rapp, J., Silman, M., and Knight, R. (2011) Microbes do not follow the elevational diversity patterns of plants and animals. Ecology 92: 797-804.
Bryant, J.A., Lamanna, C., Morlon, H., Kerkhoff, A.J., Enquist, B.J., and Green, J.L. (2008) Microbes on mountainsides: Contrasting elevational patterns of bacterial and plant diversity. Proc Natl Acad Sci USA 105: 11505-11511.

Aim  Data and analyses of elevational gradients in diversity have been central to the development and evaluation of a... more Aim  Data and analyses of elevational gradients in diversity have been central to the development and evaluation of a range of general theories of biodiversity. Elevational diversity patterns have, however, been severely understudied for microbes, which often represent decomposer subsystems. Consequently, generalities in the patterns of elevational diversity across different trophic levels remain poorly understood. Our aim was to examine elevational gradients in the diversity of macroinvertebrates, diatoms and bacteria along a stony stream that covered a large elevational gradient.

Location  Laojun Mountain, Yunnan province, China.

Methods  The sampling scheme included 26 sites spaced at elevational intervals of 89 m from 1820 to 4050 m elevation along a stony stream. Macroinvertebrate and diatom richness were determined based on the morphology of the specimens. Taxonomic richness for bacteria was quantified using a molecular fingerprinting method. Over 50 environmental variables were measured at each site to quantify environmental variables that could correlate with the patterns of diversity. We used eigenvector-based spatial filters with multiple regressions to account for spatial autocorrelation.

Results  The bacterial richness followed an unexpected monotonic increase with elevation. Diatoms decreased monotonically, and macroinvertebrate richness showed a clear unimodal pattern with elevation. The unimodal richness pattern for macroinvertebrates was best explained by the mid-domain effect (r2 = 0.72). The diatom richness was best explained by the variation in nutrient supply, and the increase in bacterial richness with elevation may be related to an increased carbon supply.

Main conclusions  We found contrasting patterns in elevational diversity among the three studied multi-trophic groups comprising unicellular and multicellular aquatic taxa. We also found that there may be fundamental differences in the mechanisms underlying these species diversity patterns.


Keywords: Bacteria; biogeography; China; diatoms; elevational gradient; macroecology; macroinvertebrates; mid-domain effect; species diversity patterns; streams