New insights into other importantPublisher: NPG; Journal: Nature: Nature; Article Type: Biology letter DOI: 10.1038/nature06269Page 2 of 33 symbiotic functions including H 2 metabolism, CO 2 -reductive acetogenesis and N 2 fixation are also provided by this first system-wide gene analysis of a microbial community specialized towards plant lignocellulose degradation. Our results underscore how complex even a 1-μl environment can be.All known termite species form obligate, nutritional mutualisms with diverse gut microbial species found nowhere else in nature 3 . Despite nearly a century of study, however, science still has only a meagre understanding of the exact roles of the host and symbiotic microbiota in the complex processes of lignocellulose degradation and conversion. Especially conspicuous is our poor understanding of the hindgut communities of wood-feeding 'higher'termites, the most species-rich and abundant of all termite lineages 4 . Higher termites do not contain hindgut flagellate protozoa, which have long been known to be sources of cellulases and hemicellulases in the 'lower' termites. The host tissue of all wood-feeding termites is known to be the source of one cellulase, a single-domain glycohydrolase family 9 enzyme that is secreted and active in the anterior compartments of the gut tract 5 . Only in recent years has research provided support for a role of termite gut bacteria in the production of relevant hydrolytic enzymes. That evidence includes the observed tight attachment of bacteria to wood particles, the antibacterial sensitivity of particle-bound cellulase activity 2 , and the discovery of a gene encoding a novel endoxylanase (glycohydrolase family 11) from bacterial DNA harvested from the gut tract of a Nasutitermes species 6 . Here, in an effort to learn about gene-centred details relevant to the diverse roles of bacterial symbionts in these successful wood-degrading insects,we initiated a metagenomic analysis of a wood-feeding 'higher' termite hindgut community, performed a proteomic analysis with clarified gut fluid from the same sample, and examined a set of candidate enzymes identified during the course of the study for demonstrable cellulase activity.A nest of an arboreal species closely related to Nasutitermes ephratae and N. corniger ( Supplementary Fig. 1) was collected near Guápiles, Costa Rica. From worker specimens, luminal contents were sampled specifically from the largest hindgut compartment, the microbedense, microlitre-sized region alternatively known as the paunch or the third proctodeal segment (P3; Fig. 1a). In the interest of interpretive clarity, we specifically excluded sampling from and analysis of the microbiota attached to the P3 epithelium and the other distinct microbial communities associated with the other hindgut compartments.Publisher: NPG; Journal: Nature: Nature; Article Type: Biology letter DOI: 10.1038/nature06269Page 3 of 33Total community DNA from pooled P3 luminal contents was purified, cloned and sequenced. About 71 million base pairs of Sang...

The guts of beetle larvae constitute a complex system where relationships among fungi, bacteria, and the insect host occur. In this study, we collected larvae of five families of wood-feeding Coleoptera in tropical forests of Costa Rica, isolated fungi and bacteria from their intestinal tracts, and determined the presence of five different pathways for lignocellulolytic activity. The fungal isolates were assigned to three phyla, 16 orders, 24 families, and 40 genera; Trichoderma was the most abundant genus, detected in all insect families and at all sites. The bacterial isolates were assigned to five phyla, 13 orders, 22 families, and 35 genera; Bacillus, Serratia, and Pseudomonas were the dominant genera, present in all the Coleopteran families. Positive results for activities related to degradation of wood components were determined in 65% and 48% of the fungal and bacterial genera, respectively. Our results showed that both the fungal and bacterial populations were highly diverse in terms of number of species and their phylogenetic composition, although the structure of the microbial communities varied with insect host family and the surrounding environment. The recurrent identification of some lignocellulolytic-positive inhabitants suggests that particular microbial groups play important roles in providing nutritional needs for the Coleopteran host.

Coleopterans are the most diverse insect order described to date. These organisms have acquired an array of survival mechanisms through their evolution, including highly efficient digestive systems. Therefore, the coleopteran intestinal microbiota constitutes an important source of novel plant cell wall-degrading enzymes with potential biotechnological applications. We isolated and described the cultivable fungi, actinomycetes and aerobic eubacteria associated with the gut of larvae and adults from six different beetle families colonizing decomposing logs in protected Costa Rican ecosystems. We obtained 611 isolates and performed phylogenetic analyses using the ITS region (fungi) and 16S rDNA (bacteria). The majority of fungal isolates belonged to the order Hypocreales (26% of 169 total), while the majority of actinomycetes belonged to the genus Streptomyces (86% of 241 total). Finally, we isolated 201 bacteria spanning 19 different families belonging into four phyla: Firmicutes, α, β and γ-proteobacteria. Subsequently, we focused on microbes isolated from Passalid beetles to test their ability to degrade plant cell wall polymers. Highest scores in these assays were achieved by a fungal isolate (Anthostomella sp.), two Streptomyces and one Bacillus bacterial isolates. Our study demonstrates that Costa Rican beetles harbor several types of cultivable microbes, some of which may be involved in symbiotic relationships that enable the insect to digest complex polymers such as lignocellulose.

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