Unraveling the impact of lanthanum on methane consuming microbial communities in rice field soils.

The discovery of the lanthanide requiring enzymes in microbes was a significant scientific discovery that opened a whole new avenue of biotechnological research of this important group of metals. However, the ecological impact of lanthanides on microbial communities utilizing methane (CH4) remains largely unexplored. In this study, a laboratory microcosm model experiment was performed using rice field soils with different pH origins (5.76, 7.2, and 8.36) and different concentrations of La3+ in the form of lanthanum chloride (LaCl3). Results clearly showed that CH4 consumption was inhibited by the addition of La3+ but that the response depended on the soil origin and pH. 16S rRNA gene sequencing revealed the genus Methylobacter, Methylosarcina, and Methylocystis as key players in CH4 consumption under La3+ addition. We suggest that the soil microbiome involved in CH4 consumption can generally tolerate addition of high concentrations of La3+, and adjustments in community composition ensured ecosystem functionality over time. As La3+ concentrations increase, the way that the soil microbiome reacts may not only differ within the same environment but also vary when comparing different environments, underscoring the need for further research into this subject.

Interactions between Cyanobacteria and Methane Processing Microbes Mitigate Methane Emissions from Rice Soils.

Cyanobacteria play a relevant role in rice soils due to their contribution to soil fertility through nitrogen (N2) fixation and as a promising strategy to mitigate methane (CH4) emissions from these systems. However, information is still limited regarding the mechanisms of cyanobacterial modulation of CH4 cycling in rice soils. Here, we focused on the response of methane cycling microbial communities to inoculation with cyanobacteria in rice soils. We performed a microcosm study comprising rice soil inoculated with either of two cyanobacterial isolates (Calothrix sp. and Nostoc sp.) obtained from a rice paddy. Our results demonstrate that cyanobacterial inoculation reduced CH4 emissions by 20 times. Yet, the effect on CH4 cycling microbes differed for the cyanobacterial strains. Type Ia methanotrophs were stimulated by Calothrix sp. in the surface layer, while Nostoc sp. had the opposite effect. The overall pmoA transcripts of Type Ib methanotrophs were stimulated by Nostoc. Methanogens were not affected in the surface layer, while their abundance was reduced in the sub surface layer by the presence of Nostoc sp. Our results indicate that mitigation of methane emission from rice soils based on cyanobacterial inoculants depends on the proper pairing of cyanobacteria-methanotrophs and their respective traits.

Methanogenesis in biogas reactors under inhibitory ammonia concentration requires community-wide tolerance.

Ammonia (NH3) inhibition represents a major limitation to methane production during anaerobic digestion of organic material in biogas reactors. This process relies on co-operative metabolic interactions between diverse taxa at the community-scale. Despite this, most investigations have focused singularly on how methanogenic Archaea respond to NH3 stress. With a high-NH3 pre-adapted and un-adapted community, this study investigated responses to NH3 inhibition both at the community-scale and down to individual taxa. The pre-adapted community performed methanogenesis under inhibitory NH3 concentrations better than the un-adapted. While many functionally important phyla were shared between the two communities, only taxa from the pre-adapted community were robust to NH3. Functionally important phyla were mostly comprised of sensitive taxa (≥ 50%), yet all groups, including methanogens, also possessed tolerant individuals (10-50%) suggesting that potential mechanisms for tolerance are non-specific and widespread. Hidden Markov Model-based phylogenetic analysis of methanogens confirmed that NH3 tolerance was not restricted to specific taxonomic groups, even at the genus level. By reconstructing covarying growth patterns via network analyses, methanogenesis by the pre-adapted community was best explained by continued metabolic interactions (edges) between tolerant methanogens and other tolerant taxa (nodes). However, under non-inhibitory conditions, sensitive taxa re-emerged to dominate the pre-adapted community, suggesting that mechanisms of NH3 tolerance can be disadvantageous to fitness without selection pressure. This study demonstrates that methanogenesis under NH3 inhibition depends on broad-scale tolerance throughout the prokaryotic community. Mechanisms for tolerance seem widespread and non-specific, which has practical significance for the development of robust methanogenic biogas communities. KEY POINTS: • Ammonia pre-adaptation allows for better methanogenesis under inhibitory conditions. • All functionally important prokaryote phyla have some ammonia tolerant individuals. • Methanogenesis was likely dependent on interactions between tolerant individuals.

On How to Be Liked in First Encounters: The Effects of Agentic and Communal Behaviors on Popularity and Unique Liking.

When meeting other people for the first time, how should one behave in order to be liked? We investigated the effects of agentic and communal behaviors on two forms of being liked: popularity (being generally liked by others) and unique liking (being uniquely liked by specific interaction partners). In a round-robin study, 139 unacquainted German adults had dyadic conversations and provided liking ratings afterward. The conversations were recorded on video, and four agentic behaviors (leading, dominant, confident, boastful) and four communal behaviors (polite, benevolent, warm, friendly) were each rated by trained observers. Participants who generally showed agentic and communal behavior were also generally liked (popularity). When participants' level of communal, but not agentic, behavior exceeded their personal standards during an interaction, they were particularly well-liked by the respective interaction partner (unique liking). The behavioral predictors of being liked thus differ, depending on whether one focuses on popularity or unique liking.

Positivity in peer perceptions over time: Personality explains variation at zero-acquaintance, popularity explains differential change.

People have characteristic ways of perceiving others' personalities. When judging others on several traits, some perceivers tend to form globally positive and others tend to form globally negative impressions. These differences, often termed perceiver effects, have mostly been conceptualized as a static construct that taps perceivers' personal stereotypes about the average other. Here, we assessed perceiver effects repeatedly in small groups of strangers who got to know each other over the course of 2-3 weeks and examined the degree to which positivity differences were stable versus developed systematically over time. Using second-order latent growth curve modeling, we tested whether initial positivity (i.e., random intercepts) could be explained by several personality variables and whether change (i.e., random slopes) could be explained by these personality variables and by perceivers' social experiences within the group. Across three studies (ns = 439, 257, and 311), personality variables characterized by specific beliefs about others, such as agreeableness and narcissistic rivalry, were found to explain initial positivity but personality was not reliably linked to changes in positivity over time. Instead, feeling liked and, to a lesser extent, being liked by one's peers partially explained changes in positivity. The results suggest that perceiver effects are best conceptualized as reflecting personal generalized stereotypes at an initial encounter but group-specific stereotypes that are fueled by social experiences as groups get acquainted. More generally, these findings suggest that perceiver effects might be a key variable to understanding reciprocal dynamics of small groups and interpersonal functioning. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Soil aeration rather than methanotrophic community drives methane uptake under drought in a subtropical forest.

Little information is available about the effects of drought on soil methane (CH4) uptake and the underlying feedback of the soil microbial community in forest biomes. More importantly, a meta-analysis of the current literature on this topic revealed that there are virtually no data available in subtropical forests. To fill the abovementioned knowledge gap, we carried out a 3-year investigation of in situ CH4 efflux under drought in a subtropical forest, and found that drought significantly increased soil CH4 uptake (P < 0.001). However, drought did not change oxidation potentials and abundances of methanotrophs, and similar methanotrophic communities were observed between the drought and ambient control sites based on metagenomic sequencing analysis. Active methanotrophic communities were dominated by the genus Methylosinus based on DNA stable-isotope probing analysis. Structural equation model analysis indicated that direct drought-derived pathway, i.e., increasing soil aerations, outweighs the indirect pathway, i.e., altering methanotrophic communities and activities, and plays a predominant role in driving soil CH4 uptake in forest ecosystems. To our knowledge, our work is the first study to investigate the effects of drought on in situ CH4 efflux and the underlying microbial mechanisms in subtropical forests.

Investigating contributors to performance evaluations in small groups: Task competence, speaking time, physical expressiveness, and likability.

This study compared the impacts of actual individual task competence, speaking time and physical expressiveness as indicators of verbal and nonverbal communication behavior, and likability on performance evaluations in a group task. 164 participants who were assigned to 41 groups first solved a problem individually and later solved it as a team. After the group interaction, participants' performance was evaluated by both their team members and qualified external observers. We found that these performance evaluations were significantly affected not only by task competence but even more by speaking time and nonverbal physical expressiveness. Likability also explained additional variance in performance evaluations. The implications of these findings are discussed for both the people being evaluated and the people doing the evaluating.

Recovery in methanotrophic activity does not reflect on the methane-driven interaction network after peat mining.

Aerobic methanotrophs are crucial in ombrotrophic peatlands, driving the methane and nitrogen cycles. Peat mining adversely affects the methanotrophs, but activity and community composition/abundances may recover after restoration. Considering that the methanotrophic activity and growth are significantly stimulated in the presence of other microorganisms, the methane-driven interaction network, encompassing methanotrophs and non-methanotrophs (i.e., methanotrophic interactome), may also be relevant in conferring community resilience. Yet, little is known of the response and recovery of the methanotrophic interactome to disturbances. Here, we determined the recovery of the methanotrophic interactome as inferred by a co-occurrence network analysis, comparing a pristine and restored peatland. We coupled a DNA-based stable isotope probing (SIP) approach using 13C-CH4 to a co-occurrence network analysis derived from the 13C-enriched 16S rRNA gene sequences to relate the response in methanotrophic activity to the structuring of the interaction network. Methanotrophic activity and abundances recovered after peat restoration since 2000. 'Methylomonaceae' was the predominantly active methanotrophs in both peatlands, but differed in the relative abundance of Methylacidiphilaceae and Methylocystis However, bacterial community composition was distinct in both peatlands. Likewise, the methanotrophic interactome was profoundly altered in the restored peatland. Structuring of the interaction network after peat mining resulted in the loss of complexity and modularity, indicating a less connected and efficient network, which may have consequences in the event of recurring/future disturbances. Therefore, determining the response of the methane-driven interaction network, in addition to relating methanotrophic activity to community composition/abundances, provided a more comprehensive understanding of the resilience of the methanotrophs.Importance The resilience and recovery of microorganisms from disturbances are often determined with regard to their activity and community composition/abundances. Rarely has the response of the network of interacting microorganisms been considered, despite accumulating evidence showing that microbial interaction modulates community functioning. Comparing the methane-driven interaction network of a pristine and restored peatland, our findings revealed that the metabolically active microorganisms were less connected and formed less modular 'hubs' in the restored peatland, indicative of a less complex network which may have consequences with recurring disturbances and environmental changes. This also suggests that the resilience and full recovery in the methanotrophic activity and abundances do not reflect on the interaction network. Therefore, it is relevant to consider the interaction-induced response, in addition to documenting changes in activity and community composition/abundances, to provide a comprehensive understanding of the resilience of microorganisms to disturbances.

No Tangible Effects of Field-Grown Cisgenic Potatoes on Soil Microbial Communities.

DNA modification techniques are increasingly applied to improve the agronomic performance of crops worldwide. Before cultivation and marketing, the environmental risks of such modified varieties must be assessed. This includes an understanding of their effects on soil microorganisms and associated ecosystem services. This study analyzed the impact of a cisgenic modification of the potato variety Desirée to enhance resistance against the late blight-causing fungus Phytophthora infestans (Oomycetes) on the abundance and diversity of rhizosphere inhabiting microbial communities. Two experimental field sites in Ireland and the Netherlands were selected, and for 2 subsequent years, the cisgenic version of Desirée was compared in the presence and absence of fungicides to its non-engineered late blight-sensitive counterpart and a conventionally bred late blight-resistant variety. At the flowering stage, total DNA was extracted from the potato rhizosphere and subjected to PCR for quantifying and sequencing bacterial 16S rRNA genes, fungal internal transcribed spacer (ITS) sequences, and nir genes encoding for bacterial nitrite reductases. Both bacterial and fungal communities responded to field conditions, potato varieties, year of cultivation, and bacteria sporadically also to fungicide treatments. At the Dutch site, without annual replication, fungicides stimulated nirK abundance for all potatoes, but with significance only for cisgenic Desirée. In all other cases, neither the abundance nor the diversity of any microbial marker differed between both Desirée versions. Overall, the study demonstrates environmental variation but also similar patterns of soil microbial diversity in potato rhizospheres and indicates that the cisgenic modification had no tangible impact on soil microbial communities.

The Predictive Validity of Explicit and Implicit Partner Evaluations for Relationship Behaviors: An Actor-Partner Interdependence Analysis.

This research introduced novel measures of explicit and implicit romantic partner evaluations and tested whether these measures predict video-observed relationship behaviors. One hundred and eighty heterosexual participants (90 couples) completed 2 measures of explicit partner evaluations, the Relationship Assessment Scale (RAS) and a short form of the Trier Partnership Inventory (TPI-S). Participants also completed measures of implicit partner evaluations, namely 2 variants of an affective priming task (APT), one of them focusing on reaction times (RT-APT) and the other one focusing on errors (EB-APT), and a facial electromyography (fEMG) task. Relationship behaviors were video-recorded in the laboratory and coded by a total of 34 independent observers. Actor-partner interdependence models were used to test whether partner evaluations predicted participants' own relationship behaviors (actor effects), and the behaviors of the partner (partner effects). Furthermore, we examined how explicit and implicit partner evaluations are related to the behaviors of the couple as a whole. Relationship behaviors were indeed predicted on all 3 levels by the RAS, the TPI-S, the EB-APT, and the fEMG, but not by the RT-APT. The research thus provides researchers with novel tools to assess explicit and implicit partner evaluations that are linked to relationship behaviors.

Environmental legacy contributes to the resilience of methane consumption in a laboratory microcosm system.

The increase of extreme drought and precipitation events due to climate change will alter microbial processes. Perturbation experiments demonstrated that microbes are sensitive to environmental alterations. However, only little is known on the legacy effects in microbial systems. Here, we designed a laboratory microcosm experiment using aerobic methane-consuming communities as a model system to test basic principles of microbial resilience and the role of changes in biomass and the presence of non-methanotrophic microbes in this process. We focused on enrichments from soil, sediment, and water reflecting communities with different legacy with respect to exposure to drought. Recovery rates, a recently proposed early warning indicator of a critical transition, were utilized as a measure to detect resilience loss of methane consumption during a series of dry/wet cycle perturbations. We observed a slowed recovery of enrichments originating from water samples, which suggests that the community's legacy with a perturbation is a contributing factor for the resilience of microbial functioning.

Accuracy of Self-Esteem Judgments at Zero Acquaintance.

OBJECTIVE: Perceptions of strangers' self-esteem can have wide-ranging interpersonal consequences. Aiming to reconcile inconsistent results from previous research that had predominantly suggested that self-esteem is a trait that can hardly be accurately judged at zero acquaintance, we examined unaquainted others' accuracy in inferring individuals' actual self-esteem. METHOD: Ninety-nine target participants (77 female; Mage = 23.5 years) were videotaped in a self-introductory situation, and self-esteem self-reports and reports by well-known informants were obtained as separate accuracy criteria. Forty unacquainted observers judged targets' self-esteem on the basis of these short video sequences (M = 23s, SD = 7.7). RESULTS: Results showed that both self-reported (r = .31, p = .002) and informant-reported self-esteem (r = .21, p = .040) of targets could be inferred by strangers. The degree of accuracy in self-esteem judgments could be explained with lens model analyses: Self- and informant-reported self-esteem predicted nonverbal and vocal friendliness, both of which predicted self-esteem judgments by observers. In addition, observers' accuracy in inferring informant-reported self-esteem was mediated by the utilization of targets' physical attractiveness. Besides using valid behavioral information to infer strangers' self-esteem, observers inappropriately relied on invalid behavioral information reflecting nonverbal, vocal, and verbal self-assuredness. CONCLUSIONS: Our findings show that strangers can quite accurately detect individuals' self-reported and informant-reported self-esteem when targets are observed in a public self-presentational situation.

Disentangling the Sources of Mimicry: Social Relations Analyses of the Link Between Mimicry and Liking.

Mimicry is an important interpersonal behavior for initiating and maintaining relationships. By observing the same participants ( N = 139) in multiple dyadic interactions (618 data points) in a round-robin design, we disentangled the extent to which mimicry is due to (a) the mimicker's general tendency to mimic (imitativity), (b) the mimickee's general tendency to evoke mimicry (imitatability), and (c) the unique dyadic relationship between the mimicker and the mimickee. We explored how these mimicry components affected liking and metaperceptions of liking (i.e., metaliking). Employing social relations models, we found substantial interindividual differences in imitativity, which predicted popularity. However, we found only small interindividual differences in imitatability. We found support for our proposition that mimicry is a substantially dyadic construct explained mostly by the unique relationship between two people. Finally, we explored the link between dyadic mimicry and liking, and we found that a person's initial liking of his or her interaction partner led to mimicry, which in turn increased the partner's liking of the mimicker.

Lanthanide-dependent cross-feeding of methane-derived carbon is linked by microbial community interactions.

The utilization of methane, a potent greenhouse gas, is an important component of local and global carbon cycles that is characterized by tight linkages between methane-utilizing (methanotrophic) and nonmethanotrophic bacteria. It has been suggested that the methanotroph sustains these nonmethanotrophs by cross-feeding, because subsequent products of the methane oxidation pathway, such as methanol, represent alternative carbon sources. We established cocultures in a microcosm model system to determine the mechanism and substrate that underlay the observed cross-feeding in the environment. Lanthanum, a rare earth element, was applied because of its increasing importance in methylotrophy. We used co-occurring strains isolated from Lake Washington sediment that are involved in methane utilization: a methanotroph and two nonmethanotrophic methylotrophs. Gene-expression profiles and mutant analyses suggest that methanol is the dominant carbon and energy source the methanotroph provides to support growth of the nonmethanotrophs. However, in the presence of the nonmethanotroph, gene expression of the dominant methanol dehydrogenase (MDH) shifts from the lanthanide-dependent MDH (XoxF)-type, to the calcium-dependent MDH (MxaF)-type. Correspondingly, methanol is released into the medium only when the methanotroph expresses the MxaF-type MDH. These results suggest a cross-feeding mechanism in which the nonmethanotrophic partner induces a change in expression of methanotroph MDHs, resulting in release of methanol for its growth. This partner-induced change in gene expression that benefits the partner is a paradigm for microbial interactions that cannot be observed in studies of pure cultures, underscoring the importance of synthetic microbial community approaches to understand environmental microbiomes.

A Synthetic Ecology Perspective: How Well Does Behavior of Model Organisms in the Laboratory Predict Microbial Activities in Natural Habitats?

In this perspective article, we question how well model organisms, the ones that are easy to cultivate in the laboratory and that show robust growth and biomass accumulation, reflect the dynamics and interactions of microbial communities observed in nature. Today's -omics toolbox allows assessing the genomic potential of microbes in natural environments in a high-throughput fashion and at a strain-level resolution. However, understanding of the details of microbial activities and of the mechanistic bases of community function still requires experimental validation in simplified and fully controlled systems such as synthetic communities. We have studied methane utilization in Lake Washington sediment for a few decades and have identified a number of species genetically equipped for this activity. We have also identified co-occurring satellite species that appear to form functional communities together with the methanotrophs. Here, we compare experimental findings from manipulation of natural communities involved in metabolism of methane in this niche with findings from manipulation of synthetic communities assembled in the laboratory of species originating from the same study site, from very simple (two-species) to rather complex (50-species) synthetic communities. We observe some common trends in community dynamics between the two types of communities, toward representation of specific functional guilds. However, we also identify strong discrepancies between the dominant methane oxidizers in synthetic communities compared to natural communities, under similar incubation conditions. These findings highlight the challenges that exist in using the synthetic community approach to modeling dynamics and species interactions in natural communities.

Compositional and functional stability of aerobic methane consuming communities in drained and rewetted peat meadows.

The restoration of peatlands is an important strategy to counteract subsidence and loss of biodiversity. However, responses of important microbial soil processes are poorly understood. We assessed functioning, diversity and spatial organization of methanotrophic communities in drained and rewetted peat meadows with different water table management and agricultural practice. Results show that the methanotrophic diversity was similar between drained and rewetted sites with a remarkable dominance of the genus Methylocystis. Enzyme kinetics depicted no major differences, indicating flexibility in the methane (CH4) concentrations that can be used by the methanotrophic community. Short-term flooding led to temporary elevated CH4 emission but to neither major changes in abundances of methane-oxidizing bacteria (MOB) nor major changes in CH4 consumption kinetics in drained agriculturally used peat meadows. Radiolabeling and autoradiographic imaging of intact soil cores revealed a markedly different spatial arrangement of the CH4 consuming zone in cores exposed to near-atmospheric and elevated CH4. The observed spatial patterns of CH4 consumption in drained peat meadows with and without short-term flooding highlighted the spatial complexity and responsiveness of the CH4 consuming zone upon environmental change. The methanotrophic microbial community is not generally altered and harbors MOB that can cover a large range of CH4 concentrations offered due to water-table fluctuations, effectively mitigating CH4 emissions.

Recurrence and Frequency of Disturbance have Cumulative Effect on Methanotrophic Activity, Abundance, and Community Structure.

Alternate prolonged drought and heavy rainfall is predicted to intensify with global warming. Desiccation-rewetting events alter the soil quality and nutrient concentrations which drive microbial-mediated processes, including methane oxidation, a key biogeochemical process catalyzed by methanotrophic bacteria. Although aerobic methanotrophs showed remarkable resilience to a suite of physical disturbances induced as a single event, their resilience to recurring disturbances is less known. Here, using a rice field soil in a microcosm study, we determined whether recurrence and frequency of desiccation-rewetting impose an accumulating effect on the methanotrophic activity. The response of key aerobic methanotroph subgroups (type Ia, Ib, and II) were monitored using qPCR assays, and was supported by a t-RFLP analysis. The methanotrophic activity was resilient to recurring desiccation-rewetting, but increasing the frequency of the disturbance by twofold significantly decreased methane uptake rate. Both the qPCR and t-RFLP analyses were congruent, showing the dominance of type Ia/Ib methanotrophs prior to disturbance, and after disturbance, the recovering community was predominantly comprised of type Ia (Methylobacter) methanotrophs. Both type Ib and type II (Methylosinus/Methylocystis) methanotrophs were adversely affected by the disturbance, but type II methanotrophs showed recovery over time, indicating relatively higher resilience to the disturbance. This revealed distinct, yet unrecognized traits among the methanotroph community members. Our results show that recurring desiccation-rewetting before a recovery in community abundance had an accumulated effect, compromising methanotrophic activity. While methanotrophs may recover well following sporadic disturbances, their resilience may reach a 'tipping point' where activity no longer recovered if disturbance persists and increase in frequency.

Trait-based approaches for understanding microbial biodiversity and ecosystem functioning.

In ecology, biodiversity-ecosystem functioning (BEF) research has seen a shift in perspective from taxonomy to function in the last two decades, with successful application of trait-based approaches. This shift offers opportunities for a deeper mechanistic understanding of the role of biodiversity in maintaining multiple ecosystem processes and services. In this paper, we highlight studies that have focused on BEF of microbial communities with an emphasis on integrating trait-based approaches to microbial ecology. In doing so, we explore some of the inherent challenges and opportunities of understanding BEF using microbial systems. For example, microbial biologists characterize communities using gene phylogenies that are often unable to resolve functional traits. Additionally, experimental designs of existing microbial BEF studies are often inadequate to unravel BEF relationships. We argue that combining eco-physiological studies with contemporary molecular tools in a trait-based framework can reinforce our ability to link microbial diversity to ecosystem processes. We conclude that such trait-based approaches are a promising framework to increase the understanding of microbial BEF relationships and thus generating systematic principles in microbial ecology and more generally ecology.

Conceptualizing functional traits and ecological characteristics of methane-oxidizing bacteria as life strategies.

Methane-oxidizing bacteria (MOB) possess the ability to use methane for energy generation and growth, thereby, providing a key ecosystem service that is highly relevant to the regulation of the global climate. MOB subgroups have different responses to key environmental controls, reflecting on their functional traits. Their unique features (C1-metabolism, unique lipids and congruence between the 16S rRNA and pmoA gene phylogeny) have facilitated numerous environmental studies, which in combination with the availability of cultured representatives, yield the most comprehensive ecological picture of any known microbial functional guild. Here, we focus on the broad MOB subgroups (type I and type II MOB), and aim to conceptualize MOB functional traits and observational characteristics derived primarily from these environmental studies to be interpreted as microbial life strategies. We focus on the functional traits, and the conditions under which these traits will render different MOB subgroups a selective advantage. We hypothesize that type I and type II MOB generally have distinct life strategies, enabling them to predominate under different conditions and maintain functionality. The ecological characteristics implicated in their adopted life strategies are discussed, and incorporated into the Competitor-Stress tolerator-Ruderal functional classification framework as put forward for plant communities. In this context, type I MOB can broadly be classified as competitor-ruderal while type II MOB fit more within the stress tolerator categories. Finally, we provide an outlook on MOB applications by exemplifying two approaches where their inferred life strategies could be exploited thereby, putting MOB into the context of microbial resource management.

Spatial patterns of methanotrophic communities along a hydrological gradient in a riparian wetland.

Microbial communities display a variety of biogeographical patterns mainly driven by large-scale environmental gradients. Here, we analysed the spatial distribution of methane-oxidizing bacteria (MOB) and methane oxidation in a strongly fluctuating environment. We investigated whether the spatial variability of the MOB community can be explained by an environmental gradient and whether this changes with different plot sizes. We applied a pmoA-specific microarray to detect MOB, measured methane oxidation, methane emissions and soil properties. All variables were measured in a 10 × 10 m, 1 × 1 m and 20 × 20 cm plot and interpreted using a geostatistical approach. Methane oxidation as well as MOB displayed spatial patterns reflected in the underlying flooding gradient. Overlapping and contrasting spatial patterns for type I and type II MOB suggested different ecological life strategies. With smaller plot size, the environmental gradient could not explain the variability in the data and local factors became more important. In conclusion, environmental gradients can generally explain variability in microbial spatial patterns; however, we think that this does not contribute to a mechanistic explanation for microbial diversity because the relevant scales for microorganisms are much smaller than those normally measured.