The ISME JournalPub Date : 2024-04-22DOI: 10.1093/ismejo/wrae067
Josep Ramoneda, Kunkun Fan, Jane M Lucas, Haiyan Chu, Andrew Bissett, Michael S Strickland, Noah Fierer
{"title":"Ecological relevance of flagellar motility in soil bacterial communities","authors":"Josep Ramoneda, Kunkun Fan, Jane M Lucas, Haiyan Chu, Andrew Bissett, Michael S Strickland, Noah Fierer","doi":"10.1093/ismejo/wrae067","DOIUrl":"https://doi.org/10.1093/ismejo/wrae067","url":null,"abstract":"Flagellar motility is a key bacterial trait as it allows bacteria to navigate their immediate surroundings. Not all bacteria are capable of flagellar motility, and the distribution of this trait, its ecological associations, and the life history strategies of flagellated taxa remain poorly characterized. We developed and validated a genome-based approach to infer the potential for flagellar motility across 12 bacterial phyla (26 192 genomes in total). The capacity for flagellar motility was associated with a higher prevalence of genes for carbohydrate metabolism and higher maximum potential growth rates, suggesting that flagellar motility is more prevalent in environments with higher carbon availability. To test this hypothesis, we applied a method to infer the prevalence of flagellar motility in whole bacterial communities from metagenomic data, and quantified the prevalence of flagellar motility across 4 independent field studies that each captured putative gradients in soil carbon availability (148 metagenomes). As expected, we observed a positive relationship between the prevalence of bacterial flagellar motility and soil carbon availability in all datasets. Since soil carbon availability is often correlated with other factors that could influence the prevalence of flagellar motility, we validated these observations using metagenomic data acquired from a soil incubation experiment where carbon availability was directly manipulated with glucose amendments. This confirmed that the prevalence of bacterial flagellar motility is consistently associated with soil carbon availability over other potential confounding factors. This work highlights the value of combining predictive genomic and metagenomic approaches to expand our understanding of microbial phenotypic traits and reveal their general environmental associations.","PeriodicalId":516554,"journal":{"name":"The ISME Journal","volume":"19 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140637707","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The ISME JournalPub Date : 2024-04-18DOI: 10.1093/ismejo/wrae064
Heidi Abresch, Tisza Bell, Scott R Miller
{"title":"Diurnal transcriptional variation is reduced in a nitrogen-fixing diatom endosymbiont","authors":"Heidi Abresch, Tisza Bell, Scott R Miller","doi":"10.1093/ismejo/wrae064","DOIUrl":"https://doi.org/10.1093/ismejo/wrae064","url":null,"abstract":"Many organisms have formed symbiotic relationships with nitrogen (N)-fixing bacteria to overcome N limitation. Diatoms in the family Rhopalodiaceae host unicellular, N-fixing cyanobacterial endosymbionts called spheroid bodies (SBs). Although this relationship is relatively young, SBs share many key features with older endosymbionts, including coordinated cell division and genome reduction. Unlike free-living relatives that fix N exclusively at night, SBs fix N largely during the day; however, how SB metabolism is regulated and coordinated with the host is not yet understood. We compared four SB genomes, including those from two new host species (Rhopalodia gibba and Epithemia adnata), to build a genome-wide phylogeny which provides a better understanding of SB evolutionary origins. Contrary to models of endosymbiotic genome reduction, the SB chromosome is unusually stable for an endosymbiont genome, likely due to the early loss of all mobile elements. Transcriptomic data for the R. gibba SB and host organelles addressed whether and how the allocation of transcriptional resources depends on light and nitrogen availability. Whereas allocation to the SB was high under all conditions, relative expression of chloroplast photosynthesis genes increased in the absence of nitrate, but this pattern was suppressed by nitrate addition. SB expression of catabolism genes was generally greater during daytime rather than at night, although the magnitude of diurnal changes in expression was modest compared to free-living cyanobacteria. We conclude that SB daytime catabolism likely supports N-fixation by linking the process to host photosynthetic carbon fixation.","PeriodicalId":516554,"journal":{"name":"The ISME Journal","volume":"46 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140620064","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The ISME JournalPub Date : 2024-04-16DOI: 10.1093/ismejo/wrae060
Delaney G Beals, Aaron W Puri
{"title":"Linking methanotroph phenotypes to genotypes using a simple spatially resolved model ecosystem","authors":"Delaney G Beals, Aaron W Puri","doi":"10.1093/ismejo/wrae060","DOIUrl":"https://doi.org/10.1093/ismejo/wrae060","url":null,"abstract":"Connecting genes to phenotypic traits in bacteria is often challenging because of a lack of environmental context in laboratory settings. Laboratory-based model ecosystems offer a means to better account for environmental conditions compared to standard planktonic cultures, and can help link genotypes and phenotypes. Here, we present a simple, cost-effective, laboratory-based model ecosystem to study aerobic methane-oxidizing bacteria (methanotrophs) within the methane-oxygen counter gradient typically found in the natural environment of these organisms. Culturing the methanotroph Methylomonas sp. strain LW13 in this system resulted in formation of a distinct horizontal band at the intersection of the counter gradient, which we discovered was not due to increased numbers of bacteria at this location but instead to an increased amount of polysaccharides. We also discovered that different methanotrophic taxa form polysaccharide bands with distinct locations and morphologies when grown in the methane-oxygen counter gradient. By comparing transcriptomic data from LW13 growing within and surrounding this band, we identified genes upregulated within the band and validated their involvement in growth and band formation within the model ecosystem using knockout strains. Notably, deletion of these genes did not negatively affect growth using standard planktonic culturing methods. This work highlights the use of a laboratory-based model ecosystem that more closely mimics the natural environment to uncover bacterial phenotypes missing from standard laboratory conditions, and to link these phenotypes with their genetic determinants.","PeriodicalId":516554,"journal":{"name":"The ISME Journal","volume":"443 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140603663","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The ISME JournalPub Date : 2024-04-16DOI: 10.1093/ismejo/wrae061
Lauren E Manck, Tyler H Coale, Brandon M Stephens, Kiefer O Forsch, Lihini I Aluwihare, Christopher L Dupont, Andrew E Allen, Katherine A Barbeau
{"title":"Iron limitation of heterotrophic bacteria in the California current system tracks relative availability of organic carbon and iron","authors":"Lauren E Manck, Tyler H Coale, Brandon M Stephens, Kiefer O Forsch, Lihini I Aluwihare, Christopher L Dupont, Andrew E Allen, Katherine A Barbeau","doi":"10.1093/ismejo/wrae061","DOIUrl":"https://doi.org/10.1093/ismejo/wrae061","url":null,"abstract":"Iron is an essential nutrient for all microorganisms in the marine environment. Iron limitation of primary production has been well documented across a significant portion of the global surface ocean, but much less is known regarding the potential for iron limitation of the marine heterotrophic microbial community. In this work, we characterize the transcriptomic response of the heterotrophic bacterial community to iron additions in the California Current System, an eastern boundary upwelling system, to detect in situ iron stress of heterotrophic bacteria. Changes in gene expression in response to iron availability by heterotrophic bacteria were detected under conditions of high productivity when carbon limitation was relieved but when iron availability remained low. The ratio of particulate organic carbon to dissolved iron emerged as a biogeochemical proxy for iron limitation of heterotrophic bacteria in this system. Iron stress was characterized by high expression levels of iron transport pathways and decreased expression of iron-containing enzymes involved in carbon metabolism, where a majority of the heterotrophic bacterial iron requirement resides. Expression of iron stress biomarkers, as identified in the iron-addition experiments, was also detected in situ. These results suggest iron availability will impact the processing of organic matter by heterotrophic bacteria with potential consequences for the marine biological carbon pump.","PeriodicalId":516554,"journal":{"name":"The ISME Journal","volume":"74 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140603920","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The ISME JournalPub Date : 2024-04-16DOI: 10.1093/ismejo/wrae063
Mengxiong Wu, Xiawei Liu, J Pamela Engelberts, Gene W Tyson, Simon J McIlroy, Jianhua Guo
{"title":"Anaerobic oxidation of ammonium and short-chain gaseous alkanes coupled to nitrate reduction by a bacterial consortium","authors":"Mengxiong Wu, Xiawei Liu, J Pamela Engelberts, Gene W Tyson, Simon J McIlroy, Jianhua Guo","doi":"10.1093/ismejo/wrae063","DOIUrl":"https://doi.org/10.1093/ismejo/wrae063","url":null,"abstract":"The bacterial species ‘Candidatus Alkanivorans nitratireducens’ was recently demonstrated to mediate nitrate-dependent anaerobic oxidation of short-chain gaseous alkanes (SCGAs). In previous bioreactor enrichment studies1,2, the species appeared to reduce nitrate in two phases, switching from denitrification to dissimilatory nitrate reduction to ammonium (DNRA) in response to nitrite accumulation. The regulation of this switch or the nature of potential syntrophic partnerships with other microorganisms remains unclear. Here, we describe anaerobic multispecies cultures of bacteria which couple the oxidation of propane and butane to nitrate reduction and the oxidation of ammonium (anammox). Batch tests with 15N-isotope labelling and multi-omic analyses collectively supported a syntrophic partnership between ‘Ca. A. nitratireducens’ and anammox bacteria, with the former species mediating nitrate-driven oxidation of SCGAs, supplying the latter with nitrite for the oxidation of ammonium. The elimination of nitrite accumulation by the anammox substantially increased SCGA and nitrate consumption rates, whereas suppressing DNRA. Removing ammonium supply led to its eventual production, the accumulation of nitrite, and the upregulation of DNRA gene expression for the abundant ‘Ca. A. nitratireducens’. Increasing the supply of SCGA had a similar effect in promoting DNRA. Our results suggest that ‘Ca. A. nitratireducens’ switches to DNRA to alleviate oxidative stress caused by nitrite accumulation, giving further insight into adaptability and ecology of this microorganism. Our findings also have important implications for the understanding of the fate of nitrogen and SCGAs in anaerobic environments.","PeriodicalId":516554,"journal":{"name":"The ISME Journal","volume":"56 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140603758","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The ISME JournalPub Date : 2024-04-16DOI: 10.1093/ismejo/wrae062
Zachary K Garvin, Sebastian R Abades, Nicole Trefault, Fernando D Alfaro, Katie Sipes, Karen G Lloyd, Tullis C Onstott
{"title":"Prevalence of trace gas-oxidizing soil bacteria increases with radial distance from Polloquere hot spring within a high-elevation Andean cold desert","authors":"Zachary K Garvin, Sebastian R Abades, Nicole Trefault, Fernando D Alfaro, Katie Sipes, Karen G Lloyd, Tullis C Onstott","doi":"10.1093/ismejo/wrae062","DOIUrl":"https://doi.org/10.1093/ismejo/wrae062","url":null,"abstract":"High-elevation arid regions harbor microbial communities reliant on metabolic niches and flexibility to survive under biologically stressful conditions, including nutrient limitation that necessitates the utilization of atmospheric trace gases as electron donors. Geothermal springs present “oases” of microbial activity, diversity, and abundance by delivering water and substrates, including reduced gases. However, it is unknown whether these springs exhibit a gradient of effects, increasing the spatial reach of their impact on trace gas-oxidizing microbes in the surrounding soils. This study assessed whether proximity to Polloquere, a high-altitude geothermal spring in an Andean salt flat, alters the diversity and metabolic structure of nearby soil bacterial populations compared to the surrounding cold desert. Recovered DNA quantities and metagenomic analyses indicate that the spring represents an oasis for microbes in this challenging environment, supporting greater biomass with more diverse metabolic functions in proximal soils that declines sharply with radial distance from the spring. Despite the sharp decrease in biomass, potential rates of atmospheric hydrogen (H2) and carbon monoxide (CO) uptake increase away from the spring. Kinetic estimates suggest that this activity is due to high-affinity trace gas consumption, likely as a survival strategy for energy and/or carbon acquisition. These results demonstrate that Polloquere regulates a gradient of diverse microbial communities and metabolisms, culminating in increased activity of trace gas-oxidizers as the influence of the spring yields to that of the regional salt flat environment. This suggests that the spring holds local importance within the context of the broader salt flat and potentially represents a model ecosystem for other geothermal systems in high-altitude desert environments.","PeriodicalId":516554,"journal":{"name":"The ISME Journal","volume":"17 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140603756","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Lactic acid bacteria modulate the CncC pathway to enhance resistance to β-cypermethrin in the oriental fruit fly","authors":"Tian Zeng, Qianyan Fu, Fangyi Luo, Jian Dai, Rong Fu, Yixiang Qi, Xiaojuan Deng, Yongyue Lu, Yijuan Xu","doi":"10.1093/ismejo/wrae058","DOIUrl":"https://doi.org/10.1093/ismejo/wrae058","url":null,"abstract":"The gut microbiota of insects has been shown to regulate host detoxification enzymes. However, the potential regulatory mechanisms involved remain unknown. Here, we report that gut bacteria increase insecticide resistance by activating the cap “n” collar isoform-C (CncC) pathway through enzymatically generated reactive oxygen species (ROS) in Bactrocera dorsalis. We demonstrated that Enterococcus casseliflavus and Lactococcus lactis, two lactic acid (LA)-producing bacteria, increase the resistance of B. dorsalis to β-cypermethrin by regulating cytochrome P450 (P450) enzymes and α-glutathione S-transferase (GST) activities. These gut symbionts also induced the expression of CncC and muscle aponeurosis fibromatosis (Maf). BdCncC knockdown led to a decrease in resistance caused by gut bacteria. Ingestion of the ROS scavenger vitamin C (VC) in resistant strain (RS) affected the expression of BdCncC/BdKeap1/BdMafK, resulting in reduced P450 and GST activity. Furthermore, feeding with E. casseliflavus or L. lactis showed that BdNOX5 increased ROS production, and BdNOX5 knockdown affected the expression of the BdCncC/BdMafK pathway and detoxification genes. Moreover, LA feeding activated the ROS-associated regulation of P450 and GST activity. Collectively, our findings indicate that symbiotic gut bacteria modulate intestinal detoxification pathways by affecting physiological biochemistry, thus providing new insights into the involvement of insect gut microbes in the development of insecticide resistance.","PeriodicalId":516554,"journal":{"name":"The ISME Journal","volume":"248 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140556515","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The ISME JournalPub Date : 2024-02-12DOI: 10.1093/ismejo/wrae025
Lingrui Qu, Chao Wang, Stefano Manzoni, Marina Dacal, Fernando T Maestre, Edith Bai
{"title":"Stronger compensatory thermal adaptation of soil microbial respiration with higher substrate availability","authors":"Lingrui Qu, Chao Wang, Stefano Manzoni, Marina Dacal, Fernando T Maestre, Edith Bai","doi":"10.1093/ismejo/wrae025","DOIUrl":"https://doi.org/10.1093/ismejo/wrae025","url":null,"abstract":"Ongoing global warming is expected to augment soil respiration by increasing microbial activity, driving self-reinforcing feedback to climate change. However, the compensatory thermal adaptation of soil microorganisms and substrate depletion may weaken the effects of rising temperature on soil respiration. To test this hypothesis, we collected soils along a large-scale forest transect in eastern China spanning a natural temperature gradient, and incubated the soils at different temperatures with or without substrate addition. We combined the exponential thermal response function and a data-driven model to study the interaction effect of thermal adaptation and substrate availability on microbial respiration and compared our results to those from two additional continental and global independent datasets. Modelled results suggested that the effect of thermal adaptation on microbial respiration was greater in areas with higher mean annual temperatures, consistent with the compensatory response to warming. In addition, the effect of thermal adaptation on microbial respiration was greater under substrate addition than under substrate depletion, which was also true for the independent datasets reanalyzed using our approach. Our results indicate that thermal adaptation in warmer regions could exert a more pronounced negative impact on microbial respiration when substrate availability is abundant. These findings improve the body of knowledge on how substrate availability influences soil microbial community-temperature interactions, which could improve estimates of projected soil carbon losses to the atmosphere through respiration.","PeriodicalId":516554,"journal":{"name":"The ISME Journal","volume":"41 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139728099","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The ISME JournalPub Date : 2024-02-08DOI: 10.1093/ismejo/wrae024
Isabella T Ritchie, Brayan Vilanova-Cuevas, Ashley Altera, Kaileigh Cornfield, Ceri Evans, James S Evans, Maria Hopson-Fernandes, Christina A Kellogg, Elayne Looker, Oliver Taylor, Ian Hewson, Mya Breitbart
{"title":"Transglobal spread of an ecologically relevant sea urchin parasite","authors":"Isabella T Ritchie, Brayan Vilanova-Cuevas, Ashley Altera, Kaileigh Cornfield, Ceri Evans, James S Evans, Maria Hopson-Fernandes, Christina A Kellogg, Elayne Looker, Oliver Taylor, Ian Hewson, Mya Breitbart","doi":"10.1093/ismejo/wrae024","DOIUrl":"https://doi.org/10.1093/ismejo/wrae024","url":null,"abstract":"Mass mortality of the dominant coral reef herbivore Diadema antillarum in the Caribbean in the early 1980s led to a persistent phase shift from coral- to algal-dominated reefs. In 2022, a scuticociliate most closely related to Philaster apodigitiformis caused further mass mortality of D. antillarum across the Caribbean, leading to >95% mortality at affected sites. Mortality was also reported in the related species Diadema setosum in the Mediterranean in 2022, where urchins experienced gross signs compatible with scuticociliatosis. However, the causative agent of the Mediterranean outbreak has not yet been determined. In April 2023, mass mortality of D. setosum occurred along the Sultanate of Oman’s coastline. Urchins displayed signs compatible with scuticociliatosis including abnormal behavior, drooping and loss of spines, followed by tissue necrosis and death. Here we report the detection of an 18S rRNA gene sequence in abnormal urchins from Muscat, Oman that is identical to the Philaster strain responsible for D. antillarum mass mortality in the Caribbean. We also show that scuticociliatosis signs can be elicited in D. setosum by experimental challenge with the cultivated Philaster strain associated with Caribbean scuticociliatosis. These results demonstrate the Philaster sp. associated with D. antillarum mass mortality has rapidly spread to geographically distant coral reefs, compelling global-scale awareness and monitoring for this devastating condition through field surveys, microscopy, and molecular microbiological approaches, and prompting investigation of long-range transmission mechanisms.","PeriodicalId":516554,"journal":{"name":"The ISME Journal","volume":"221 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139716983","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The ISME JournalPub Date : 2024-02-05DOI: 10.1093/ismejo/wrae022
Mira D Liu, Yongle Du, Sara K Koupaei, Nicole R Kim, Monika S Fischer, Wenjun Zhang, Matthew F Traxler
{"title":"Surface-active antibiotic production as a multifunctional adaptation for postfire microorganisms","authors":"Mira D Liu, Yongle Du, Sara K Koupaei, Nicole R Kim, Monika S Fischer, Wenjun Zhang, Matthew F Traxler","doi":"10.1093/ismejo/wrae022","DOIUrl":"https://doi.org/10.1093/ismejo/wrae022","url":null,"abstract":"Wildfires affect soils in multiple ways, leading to numerous challenges for colonizing microorganisms. While it is thought that fire-adapted microorganisms lie at the forefront of postfire ecosystem recovery, the specific strategies that these organisms use to thrive in burned soils remain largely unknown. Through bioactivity screening of bacterial isolates from burned soils, we discovered that several Paraburkholderia spp. isolates produced a set of unusual rhamnolipid surfactants with a natural methyl ester modification. These rhamnolipid methyl esters (RLMEs) exhibited enhanced antimicrobial activity against other postfire microbial isolates, including pyrophilous Pyronema fungi and Amycolatopsis bacteria, compared to the typical rhamnolipids made by organisms such as Pseudomonas spp. RLMEs also showed enhanced surfactant properties and facilitated bacterial motility on agar surfaces. In vitro assays further demonstrated that RLMEs improved aqueous solubilization of polycyclic aromatic hydrocarbons, which are potential carbon sources found in char. Identification of the rhamnolipid biosynthesis genes in the postfire isolate, Paraburkholderia kirstenboschensis str. F3, led to the discovery of rhlM, whose gene product is responsible for the unique methylation of rhamnolipid substrates. RhlM is the first characterized bacterial representative of a large class of integral membrane methyltransferases that are widespread in bacteria. These results indicate multiple roles for RLMEs in the postfire lifestyle of Paraburkholderia isolates, including enhanced dispersal, solubilization of potential nutrients, and inhibition of competitors. Our findings shed new light on the chemical adaptations that bacteria employ to navigate, grow, and outcompete other soil community members in postfire environments.","PeriodicalId":516554,"journal":{"name":"The ISME Journal","volume":"10 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139700852","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}