Symbiotic Communities Research Articles

A newly discovered Gigantidas bivalve mussel from the Onnuri Vent Field in the northern Central Indian Ridge

We describe a new vent mussel species, Gigantidas vrijenhoeki n. sp., from material collected at a depth of 2022 m in the newly discovered Onnuri Vent Field (OVF) during the 2018 expedition to the Central Indian Ridge. This large modioliform mussel thrives around diffusive vents in aggregation with another dominant hydrothermal vent mussel, Bathymodiolus marisindicus. G. vrijenhoeki n. sp. was distinguished from its neighboring B. marisindicus by its distinct shell profile, which consists of an elongated shell with a short and low anterior region, high expanded posterior region, and deep ventral concavity. Visually, the new mussel species resembles G. securiformis; however, it is clearly distinguished by several shell and anatomical features. Genetically, the new species is closely related to two undescribed Gigantidas species found in the cold seeps of the western Pacific. Phylogenetic analysis of G. vrijenhoeki n. sp. supports the connectivity of vent fauna between the Indian Ocean and the western Pacific in the past. To the best of our knowledge, this is the first record of a Gigantidas species in the Indian Ocean. In addition, we found gill-associated sulfur-oxidizing and methane-oxidizing bacteria, Gammaproteobacteria and Epsilonproteobacteria, symbionts present on this new species. Their composition was clearly different from symbionts found on the co-occurring B. marisindicus at the OVF. Notably, the sulfurovum-related Epsilonproteobacteria on the G. vrijenhoeki n. sp. were phylogenetically distinct from the family of Bathymodiolinae-related Epsilonproteobacteria. Taken together, the co-occurrence of two mussel species at the new vent field and their distinct gill symbiotic communities provides a useful setting in which to study the genetic connectivity of vent mussels along the Central Indian Ridge and the evolutionary dynamics between host mussels and symbionts.

Periodontopathogens: a new view. Systematic review. Part 1

Relevance. The modern view of periodontitis as a dysbiotic disease that occurs as a result of changes in the microbial composition of the subgingival region is considered in a systematic review. Purpose. To study a new paradigm of development of generalized periodontitis. Materials and methods. Randomized controlled trials (RCTS) were selected for the study, including cluster RCTS, controlled (non-randomized) microbiological and clinical studies of the oral microbiome in adult patients with generalized periodontitis over the past 10 years. Results. The development of periodontal dysbiosis occurs over a period of time, which slowly turns the symbiotic association of the host and microbe into a pathogenic one. This review examines the current paradigm of periodontitis progression, which calls into question the traditional concept of a disease induced by several particular periodontal pathogens belonging to the red complex.Conclusions. As follows from modern literature periodontitis is to a certain extent caused by the transition from a harmonious symbiotic bacterial community to a dysbiotic one. Recent scientific studies have shown that not single microorganism is not able to cause disease but the microbial community as a whole leads to the development of pathology.

What Is in Umbilicaria pustulata? A Metagenomic Approach to Reconstruct the Holo-Genome of a Lichen.

Lichens are valuable models in symbiosis research and promising sources of biosynthetic genes for biotechnological applications. Most lichenized fungi grow slowly, resist aposymbiotic cultivation, and are poor candidates for experimentation. Obtaining contiguous, high-quality genomes for such symbiotic communities is technically challenging. Here, we present the first assembly of a lichen holo-genome from metagenomic whole-genome shotgun data comprising both PacBio long reads and Illumina short reads. The nuclear genomes of the two primary components of the lichen symbiosis—the fungus Umbilicaria pustulata (33 Mb) and the green alga Trebouxia sp. (53 Mb)—were assembled at contiguities comparable to single-species assemblies. The analysis of the read coverage pattern revealed a relative abundance of fungal to algal nuclei of ∼20:1. Gap-free, circular sequences for all organellar genomes were obtained. The bacterial community is dominated by Acidobacteriaceae and encompasses strains closely related to bacteria isolated from other lichens. Gene set analyses showed no evidence of horizontal gene transfer from algae or bacteria into the fungal genome. Our data suggest a lineage-specific loss of a putative gibberellin-20-oxidase in the fungus, a gene fusion in the fungal mitochondrion, and a relocation of an algal chloroplast gene to the algal nucleus. Major technical obstacles during reconstruction of the holo-genome were coverage differences among individual genomes surpassing three orders of magnitude. Moreover, we show that GC-rich inverted repeats paired with nonrandom sequencing error in PacBio data can result in missing gene predictions. This likely poses a general problem for genome assemblies based on long reads.

Long-lasting effects of antibiotics on bacterial communities of adult flies.

Insect symbionts benefit their host and their study requires large spectrum antibiotic use like tetracycline to weaken or suppress symbiotic communities. While antibiotics have a negative impact on insect fitness, little is known about antibiotic effects on insect microbial communities and how long they last. We characterized the bacterial communities of adult cabbage root fly Delia radicum in a Wolbachia-free population and evaluated the effect of tetracycline treatment on these communities over several generations. Three D. radicum generations were used: the first- and second-generation flies either ingested tetracycline or not, while the third-generation flies were untreated but differed with their parents and/or grandparents that had or had not been treated. Fly bacterial communities were sequenced using a 16S rRNA gene. Tetracycline decreased fly bacterial diversity and induced modifications in both bacterial abundance and relative frequencies, still visible on untreated offspring whose parents and/or grandparents had been treated, therefore demonstrating long-lasting transgenerational effects on animal microbiomes after antibiotic treatment. Flies with an antibiotic history shared bacterial genera, potentially tetracycline resistant and heritable. Next, the transmission should be investigated by comparing several insect development stages and plant compartments to assess vertical and horizontal transmissions of D. radicum bacterial communities.

A Simple Method for Extraction of the Horse Feces Virome DNA, Suitable for Oxford Nanopore Sequencing

Metagenomics of the viromes associated with symbiotic microbial communities is a rapidly expanding field of research. Most of the relevant studies deal with the viral communities of human or animal feces. The novel technology of long-reads sequencing from Oxford Nanopore that became available during the last years provides outstanding new possibilities for research of uncultured viral communities. However, compared to classical NGS sequencing, this technology is much more sensitive to the quantity and quality of sequenced DNA. We developed a simple, cheap, and efficient protocol for extraction of total virome DNA from horse feces yielding the DNA samples suitable for long-read sequencing. This method can be adapted for the work with other difficult objects.

Симбіонтні мікробні угруповання комах: функціонування та ініціація потенціалу ентомопатогенної дії на прикладі Bacillus thuringiensis

Симбіонтні мікробні угруповання комах: функціонування та ініціація потенціалу ентомопатогенної дії на прикладі Bacillus thuringiensis

Changes in the community structure of the symbiotic microbes of wild amphibians from the eastern edge of the Tibetan Plateau

Environment has a potential effect on the animal symbiotic microbiome. Here, to study the potential relationship of the symbiotic microbiomes of wild amphibians with altitude, we collected the gut and skin samples from frogs (nine species) and the environmental samples (water and soil samples) from the Leshan Mountains (altitude: 360–410 m) and Gongga Mountains (altitude: 3340–3989 m) on the eastern edge of the Tibetan Plateau. Bufo gargarizans (Bg) samples were collected from both the Leshan and Gongga mountain regions (Bg was the only species sampled on both mountains). The DNA extracted from each sample was performed high‐throughput sequencing (MiSeq) of bacterial 16S rRNA gene amplicons. High relative abundance of Caulobacteraceae and Sphingomonadaceae was found in skin samples from both Bg and the other high‐altitude amphibians (nine species combined). High relative abundance of Coxiellaceae and Mycoplasmataceae was found in gut samples from both Bg and the other high‐altitude amphibians. Furthermore, the alpha and beta diversities of skin and gut samples from Bg and the other amphibian species (nine species combined) were similar. In terms of the symbiotic microbial community, the low‐altitude samples were less diverse and more similar to each other than the high‐altitude samples were. We speculated that extreme high‐altitude environments and host phylogeny may affect the amphibian microbiome. Despite the distinct microbial community differences between the skin and gut microbiomes, some functions were similar in the Bg and combined high‐altitude samples. The Bg and high‐altitude skin samples had higher oxidative stress tolerance and biofilm formation than the low‐altitude skin samples. However, the opposite results were observed for the Bg and high‐altitude gut samples. Further study is required to determine whether these characteristics favor high‐altitude amphibian adaptation to extreme environments.

Host population genetics and biogeography structure the microbiome of the sponge Cliona delitrix.

Sponges occur across diverse marine biomes and host internal microbial communities that can provide critical ecological functions. While strong patterns of host specificity have been observed consistently in sponge microbiomes, the precise ecological relationships between hosts and their symbiotic microbial communities remain to be fully delineated. In the current study, we investigate the relative roles of host population genetics and biogeography in structuring the microbial communities hosted by the excavating sponge Cliona delitrix. A total of 53 samples, previously used to demarcate the population genetic structure of C. delitrix, were selected from two locations in the Caribbean Sea and from eight locations across the reefs of Florida and the Bahamas. Microbial community diversity and composition were measured using Illumina‐based high‐throughput sequencing of the 16S rRNA V4 region and related to host population structure and geographic distribution. Most operational taxonomic units (OTUs) specific to Cliona delitrix microbiomes were rare, while other OTUs were shared with congeneric hosts. Across a large regional scale (>1,000 km), geographic distance was associated with considerable variability of the sponge microbiome, suggesting a distance–decay relationship, but little impact over smaller spatial scales (<300 km) was observed. Host population structure had a moderate effect on the structure of these microbial communities, regardless of geographic distance. These results support the interplay between geographic, environmental, and host factors as forces determining the community structure of microbiomes associated with C. delitrix. Moreover, these data suggest that the mechanisms of host regulation can be observed at the population genetic scale, prior to the onset of speciation.

The Diversity and Distribution of Wolbachia, Rhizobiales, and Ophiocordyceps Within the Widespread Neotropical Turtle Ant, Cephalotes atratus (Hymenoptera: Formicidae).

Ants are an ecologically and evolutionarily diverse group, and they harbor a wide range of symbiotic microbial communities that often greatly affect their biology. Turtle ants (genus Cephalotes) engage in mutualistic relationships with gut bacteria and are exploited by microbial parasites. Studies have shown that associations among these microbial lineages and the turtle ant hosts vary geographically. However, these studies have been limited, and thorough within-species analyses of the variation and structure of these microbial communities have yet to be conducted. The giant turtle ant, Cephalotes atratus (Linnaeus 1758), is a geographically widespread, genetically diverse Neotropical species that has been sampled extensively across its geographic range, making it ideal for analysis of microbial associations. In this study, we verified the presence, genetic variation, and geographic patterns at the individual, colony, and population level of three microbial groups associated with the giant turtle ant: Wolbachia, a genus of facultative bacteria which are often parasitic, affecting host reproduction; Rhizobiales, a mutualistic order of bacteria hypothesized to be an obligate nutritional symbiont in turtle ants; and Ophiocordyceps, a genus of endoparasitic fungi infecting many arthropod species by manipulating their behavior for fungal reproduction. In this study, we found varying degrees of prevalence for two distantly related genotypes (haplogroups) of Wolbachia and high degree of prevalence of Rhizobiales across colonies with little genetic variation. In addition, we found low occurrence of Ophiocordyceps. This study highlights a key first step in understanding the diversity, distribution, and prevalence of the microbial community of C. atratus.

疫區、口罩與無症狀感染者——新型冠狀病毒疫情如何破壞了我們的公共生活

LANGUAGE NOTE | Document text in Chinese; abstract also in English.新型冠狀病毒疫情所帶來的巨大的、彌散的、不確定的威脅，使社會公共生活中人們熟悉和信賴的闢係與界限變得糢糊。在這種情沉下，人們最需要的就是發現“敵人”，重新為人際闢係和公共生活找到確定性。在精準、高效的科學檢測手段獲得普及之前，人們不得不選擇簡易的標籤化方法進行區 分。疫區標籤是通過清潔與污染的劃分來保護現有的正常生活秩序，但在找到敵人的過程中有可能造成對無辜者的誤傷；口罩標數的使用則首先指向了人群的區分與界限，是想要在混亂之中先找到群體邊界和歸屬感，但有可能會轉變為主動去創造敵人。這些手段的根本目的都是為了實現自我保護，但在這樣的利害關係考量之外，還存在著某種個人對他人和公共生活的普遍義務，只有我們能夠在生存危機的巨大壓力下選擇堅持這一道德義務，才能為戰勝疫情奠定真正的希望。當代的公共生活是一個緊密地彼此闢聯、密切交通、相互滲入和共生性的整體，但這個共同體本身是十分脆弱的，在巨大的安全壓力之下很容易滑向分裂與隔離。新型冠狀病毒疫情既是一次嚴峻的挑戰，又是一次重要的演習，我們需要在其中學到足夠多的經驗，為未來可能出現的更大危機做好準備。The huge, diffuse, and uncertain threat brought about by the Covid-19 epidemic has blurred familiar and trusted relationships and the boundaries of public life. Under such circumstances, what people need most is to uncover the “enemy” and regain certainty in interpersonal relations and the public sphere. Before the popularization of accurate and efficient scientific detection methods, people used simple labeling methods to tell concepts apart. Labeling epidemic areas protects the status quo by demarcating cleanliness from pollution, but in finding the enemy, doing so may cause accidental injury to the innocent. Labeling masks allows distinctions in the crowd so that group boundaries and senses of belonging can be found in chaos. However, such labeling may lead to the creation of enemies. The fundamental goal of these methods is self-protection. Nevertheless, in addition to such considerations, individuals have a wider moral obligation to others and to public life. Only by choosing to adhere to our moral obligations under the enormous pressure of a survival crisis can we find true hope to defeat the epidemic. Contemporary public life is a symbiotic community that is closely related, in close communication, and mutually enmeshed. Such a community is very fragile, and it can easily slip into divisiveness and become isolated under huge security pressures. The Covid-19 epidemic is not only a serious challenge, but also an important exercise. We need to learn enough to prepare for greater crisis that may arise in the future.DOWNLOAD HISTORY | This article has been downloaded 31 times in Digital Commons before migrating into this platform.

Patterns and Mechanisms of Lexical Changes in the Languages of Symbiotic Communities: Kinship Terminology in Karashevo (Banat, Romania)

This article deals with the ethnolinguistic situation in one of the most archaic areas of language and cultural contact between South Slavic and Eastern Romance populations — the Karashevo microregion in Banat, Romania. For the first time, the lexical-semantic group of kinship terms in the Krashovani dialects from the Slavic-speaking village of Carașova and the Romanian-speaking village of Iabalcea is being analysed in a comparative perspective as two separate linguistic codes which “serve” the same local culture. The main goal of the research was to investigate patterns of borrowing mechanisms which could link lexical (sub)systems of spiritual cultureunder the conditions of intimate language contact in symbiotic communities. It will be shown that, in such situations, the equivalent translation becomes relevant as a specific strategy of linguistic code interrelationships. Even though kinship terminology in closely contacting dialectshas the potential to help linguists trace back the socio-historical conditions and outcomes of language contact (such as marriage patterns), linguistic methods have their limitations in the case of poorly documented vernaculars. These limitations could be overcome by compiling more data on “isocontacting” communities and, possibly, by analysing this data using quantitative tools.

Isolation and Characterization of the Strains Producing Bacterial Cellulose

Two new strains producing bacterial cellulose were isolated from the Kombucha and Tibicos symbiotic communities. Based on the 16S rRNA gene analysis and the morphological, biochemical, and physiological characteristics, the strains were identified as Komagataeibacter sucrofermentans H 110 and Komagataeibacter hansenii C 110; the strains were deposited to the All-Russian Collection of Industrial Microorganisms under accession nos. VKPM B-11267 and VKPM B-12950, respectively. The isolates have high productivity and form up to 8.2–9.5 g/L bacterial cellulose on media with food industry wastes.

Functioning of the Lubomirskia baicalensis symbiotic community under the conditions of a model experiment

Functioning of the Lubomirskia baicalensis symbiotic community under the conditions of a model experiment

The eukaryome: Diversity and role of microeukaryotic organisms associated with animal hosts

Abstract Awareness of the roles that host‐associated microbes play in host biology has escalated in recent years. However, microbiome studies have focused essentially on bacteria, and overall, we know little about the role of host‐associated eukaryotes outside the field of parasitology. Despite that, eukaryotes and microeukaryotes in particular are known to be common inhabitants of animals. In many cases, and/or for long periods of time, these associations are not associated with clinical signs of disease. Unlike the study of bacterial microbiomes, the study of the microeukaryotes associated with animals has largely been restricted to visual identification or molecular targeting of particular groups. So far, since the publication of the influential Human Microbiome Project Consortium paper in 2012, few studies have been published dealing with the microeukaryotes using a high‐throughput barcoding ‘microbiome‐like’ approach in animals. Nonetheless, microeukaryotes have an impact on the host physiology and lifestyle and also on the diversity and composition of the wider symbiotic community of bacteria and viruses. Beyond being parasites, microeukaryotes have many different roles in animals. For example, they directly interact with the host immune system in mammals; they have a key role on cellulose degradation, lignocellulose in xylophage termites and cockroaches; and they have an essential role in providing photosynthates to reef‐building corals. Certain microeukaryotic lineages have diversified within hosts more than others. These cases of co‐evolution led to different forms of symbiosis: from mutualism (like Symbiodinium in corals or parabasalians in termites), to commensalism (Blastocystis in humans) or to strict parasitism (apicomplexans or microsporidians in a broad range of hosts). We will review the ecological context and the evolutionary mechanisms that ended up in these different symbiotic scenarios, across the taxonomic range of both symbionts and their metazoan hosts. Host‐associated microeukaryotes have impacts at many levels, from individual animal health to ecosystems and to agroeconomy. Therefore, it is crucial to have a better understanding of their diversity and roles. Novel methodologies are being developed to access the eukaryotic fraction of the microbiome using high‐throughput methods. From ‐omics, to imaging and barcoding approaches biased against metazoans, these novel methodologies and strategies are helping us to increase and improve our knowledge of microeukaryotes in animal‐associated environments. A free Plain Language Summary can be found within the Supporting Information of this article.

Functional Genomics of a Symbiotic Community: Shared Traits in the Olive Fruit Fly Gut Microbiota.

The olive fruit fly Bactrocera oleae is a major pest of olives worldwide and houses a specialized gut microbiota dominated by the obligate symbiont “Candidatus Erwinia dacicola.” Candidatus Erwinia dacicola is thought to supplement dietary nitrogen to the host, with only indirect evidence for this hypothesis so far. Here, we sought to investigate the contribution of the symbiosis to insect fitness and explore the ecology of the insect gut. For this purpose, we examined the composition of bacterial communities associated with Cretan olive fruit fly populations, and inspected several genomes and one transcriptome assembly. We identified, and reconstructed the genome of, a novel component of the gut microbiota, Tatumella sp. TA1, which is stably associated with Mediterranean olive fruit fly populations. We also reconstructed a number of pathways related to nitrogen assimilation and interactions with the host. The results show that, despite variation in taxa composition of the gut microbial community, core functions related to the symbiosis are maintained. Functional redundancy between different microbial taxa was observed for genes involved in urea hydrolysis. The latter is encoded in the obligate symbiont genome by a conserved urease operon, likely acquired by horizontal gene transfer, based on phylogenetic evidence. A potential underlying mechanism is the action of mobile elements, especially abundant in the Ca. E. dacicola genome. This finding, along with the identification, in the studied genomes, of extracellular surface structure components that may mediate interactions within the gut community, suggest that ongoing and past genetic exchanges between microbes may have shaped the symbiosis.

The effects of glyphosate and AMPA on the mediterranean mussel Mytilus galloprovincialis and its microbiota

Glyphosate, the most widely used herbicide worldwide, targets the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) enzyme in the shikimate pathway found in plants and some microorganisms. While the potential for glyphosate to induce a broad range of biological effects in exposed organisms has been demonstrated, the global molecular mechanisms of toxicity and potential effects in bacterial symbionts remain unclear, in particular for ecologically important marine species such as bivalve molluscs. Here, the effects of glyphosate (GLY), its degradation product aminomethylphosphonic acid (AMPA), and a mixture of both (MIX) on the mussel M. galloprovincialis were assessed in a controlled experiment. For the first time, next generation sequencing (RNA-seq and 16S rRNA amplicon sequencing) was used to evaluate such effects at the molecular level in both the host and its respective microbiota. The results suggest that the variable capacity of bacterial species to proliferate in the presence of these compounds and the impairment of host physiological homeostasis due to AMPA and GLY toxicity may cause significant perturbations to the digestive gland microbiota, as well as elicit the spread of potential opportunistic pathogens such as Vibrio spp.. The consequent host-immune system activation identified at the molecular and cellular level could be aimed at controlling changes occurring in the composition of symbiotic microbial communities. Overall, our data raise further concerns about the potential adverse effects of glyphosate and AMPA in marine species, suggesting that both the effects of direct toxicity and the ensuing changes occurring in the host-microbial community must be taken into consideration to determine the overall ecotoxicological hazard of these compounds.

Community Detection Based on Symbiotic Organisms Search and Neighborhood Information

Modularity optimization methods based on nature-inspired metaheuristics are popular and competent for community detection in complex networks. However, on some real-world networks with complex and vague structures, most contemporary algorithms are difficult to obtain the global optimal partition. There are two key factors that are seriously affecting the global optimization capability: one is the convergence performance of the incorporated optimization strategy and the other is the sufficient and rational utilization of network topological information. In this article, a novel community detection method is proposed, named symbiotic organisms search community detection (SOSCD). The bio-inspired metaheuristic [symbiotic organisms search (SOS)] is discretized and utilized as the optimization strategy to improve global convergence performance of modularity optimization. Meanwhile, by utilizing neighborhood information of each node to guide community optimization, two different local search (LS) schemes are designed to intensify exploitation and, thus, assisting the global search, including the neighbor-based community modification (NCM) and the neighbor-based LS (NLS). Experimental results on both synthetic and real-world networks have validated the effectiveness and superiority of the proposed operations in SOSCD. Moreover, SOSCD can significantly improve the precision and stability of the identified optimal partition, comparing with many state-of-the-art modularity optimization algorithms.

Potential of a fly gut microbiota incorporated gel-based larval diet for rearing Bactrocera dorsalis (Hendel)

BackgroundThe Oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), is an important polyphagous pest of horticultural produce. The sterile insect technique (SIT) is a proven control method against many insect pests, including fruit flies, under area-wide pest management programs. High quality mass-rearing process and the cost-effective production of sterile target species are important for SIT. Irradiation is reported to cause severe damage to the symbiotic community structure in the mid gut of fruit fly species, impairing SIT success. However, studies have found that target-specific manipulation of insect gut bacteria can positively impact the overall fitness of SIT-specific insects.ResultsTwelve bacterial genera were isolated and identified from B. dorsalis eggs, third instars larval gut and adults gut. The bacterial genera were Acinetobacter, Alcaligenes, Citrobacter, Pseudomonas, Proteus, and Stenotrophomonas, belonging to the Enterobacteriaceae family. Larval diet enrichment with the selected bacterial isolate, Proteus sp. was found to improve adult emergence, percentage of male, and survival under stress. However, no significant changes were recorded in B. dorsalis egg hatching, pupal yield, pupal weight, duration of the larval stage, or flight ability.ConclusionsThese findings support the hypothesis that gut bacterial isolates can be used in conjunction with SIT. The newly developed gel-based larval diet incorporated with Proteus sp. isolates can be used for large-scale mass rearing of B. dorsalis in the SIT program.

A Natural High-Sugar Diet Has Different Effects on the Prokaryotic Community Structures of Lower and Higher Termites (Blattaria).

The lignocellulosic digestive symbiosis in termites is a dynamic survival adaptation system. While the contribution of hereditary and habitat factors to the development of the symbiotic bacterial community of termites had been confirmed, the manner in which these factors affect functional synergism among different bacterial lineages has still not been fully elucidated. Therefore, the 16S rRNA gene libraries of Odontotermes formosanus Shiraki (Blattodea: Termitidae) and Coptotermes formosanus Shiraki (Blattodea: Rhinotermitidae) sampled from sugarcane fields (high sugar) or pine tree forests (no free sugar) were sequenced. The results verify that the prokaryotic community structures of termites could be significantly reshaped by native dietary isolation within a species. Although the most dominant phyla are convergent in all samples, their relative abundances in these two termite species exhibited a reverse variation pattern when the termite hosts were fed on the high-sugar diet. Furthermore, we showed that the taxonomic composition of the dominant phyla at the family or genus level differentiate depending on the diet and the host phylogeny. We hypothesize that the flexible bacterial assemblages at low taxonomic level might exert variable functional collaboration to accommodate to high-sugar diet. In addition, the functional predictions of Tax4Fun suggest a stable metabolic functional structure of the microbial communities of the termites in both different diet habitats and taxonomy. We propose that the symbiotic bacterial community in different host termites developed a different functional synergistic pattern, which may be essential to maintain the stability of the overall metabolic function for the survival of termites.

Origins and Bioactivities of Natural Compounds Derived from Marine Ascidians and Their Symbionts.

Marine ascidians are becoming important drug sources that provide abundant secondary metabolites with novel structures and high bioactivities. As one of the most chemically prolific marine animals, more than 1200 inspirational natural products, such as alkaloids, peptides, and polyketides, with intricate and novel chemical structures have been identified from ascidians. Some of them have been successfully developed as lead compounds or highly efficient drugs. Although numerous compounds that exist in ascidians have been structurally and functionally identified, their origins are not clear. Interestingly, growing evidence has shown that these natural products not only come from ascidians, but they also originate from symbiotic microbes. This review classifies the identified natural products from ascidians and the associated symbionts. Then, we discuss the diversity of ascidian symbiotic microbe communities, which synthesize diverse natural products that are beneficial for the hosts. Identification of the complex interactions between the symbiont and the host is a useful approach to discovering ways that direct the biosynthesis of novel bioactive compounds with pharmaceutical potentials.