Phylogenetic diversity of nitrogen fixation genes in the symbiotic microbial community in the gut of diverse termites.

Nitrogen fixation by the microorganisms in the gut of termites is one of the crucial aspects of symbiosis, since termites usually thrive on a nitrogen-poor diet. The phylogenetic diversity of the nitrogen-fixing organisms within the symbiotic community in the guts of various termite species was investigated without culturing the resident microorganisms. A portion of the dinitrogenase reductase gene (nifH) was directly amplified from DNA extracted from the mixed population in the termite gut. Analysis of deduced amino acid sequences of the products of the clonally isolated nifH genes revealed the presence of diverse nifH sequences in most of the individual termite species, and their constituents were considerably different among termite species. A majority of the nifH sequences from six lower termites, which showed significant levels of nitrogen fixation activity, could be assigned to either the anaerobic nif group (consisting of clostridia and sulfur reducers) or the alternative nif methanogen group among the nifH phylogenetic groups. In the case of three higher termites, which showed only low levels of nitrogen fixation activity, a large number of the sequences were assigned to the most divergent nif group, probably functioning in some process other than nitrogen fixation and being derived from methanogenic archaea. The nifH groups detected were similar within each termite family but different among the termite families, suggesting an evolutionary trend reflecting the diazotrophic habitats in the symbiotic community. Within these phylogenetic groups, the sequences from the termites formed lineages distinct from those previously recognized in studies using classical microbiological techniques, and several sequence clusters unique to termites were found. The results indicate the presence of diverse potentially nitrogen-fixing microbial assemblages in the guts of termites, and the majority of them are as yet uncharacterized.     

Formyltetrahydrofolate synthetase gene diversity in the guts of higher termites with different diets and lifestyles

In this study, we examine gene diversity for formyl-tetrahydrofolate synthetase (FTHFS), a key enzyme in homoacetogenesis, recovered from the gut microbiota of six species of higher termites. The "higher" termites (family Termitidae), which represent the majority of extant termite species and genera, engage in a broader diversity of feeding and nesting styles than the "lower" termites. Previous studies of termite gut homoacetogenesis have focused on wood-feeding lower termites, from which the preponderance of FTHFS sequences recovered were related to those from acetogenic treponemes. While sequences belonging to this group were present in the guts of all six higher termites examined, treponeme-like FTHFS sequences represented the majority of recovered sequences in only two species (a wood-feeding Nasutitermes sp. and a palm-feeding Microcerotermes sp.). The remaining four termite species analyzed (a Gnathamitermes sp. and two Amitermes spp. that were recovered from subterranean nests with indeterminate feeding strategies and a litter-feeding Rhynchotermes sp.) yielded novel FTHFS clades not observed in lower termites. These termites yielded two distinct clusters of probable purinolytic Firmicutes and a large group of potential homoacetogens related to sequences previously recovered from the guts of omnivorous cockroaches. These findings suggest that the gut environments of different higher termite species may select for different groups of homoacetogens, with some species hosting treponeme-dominated homoacetogen populations similar to those of wood-feeding, lower termites while others host Firmicutes-dominated communities more similar to those of omnivorous cockroaches.     

Lignocellulose degradation by microorganisms from termite hills and termite guts: A survey on the present state of art

Abstract: In several aspects termites are a fascinating group of insects having attracted the interest of many researchers. They exhibit a complex social behavior and caste differentiation occurring elsewhere only among the hymenoptera. In an enlarged part of the hindgut, the paunch, termites have established a unique symbiotic association with prokaryotic and eukaryotic microorganisms. A similar flora is also found in wood-eating roaches of the genus Cryptocercus . The study of symbiosis between termites and their intestinal microbes is of general interest, because due to this symbiotic interaction termites can feed on complex biopolymers such as wood. Flagellates and bacteria occur in the gut of lower termites, while higher termites possess only bacteria. In particular spirochetes are abundant in the termite gut. Apart from spirochetes and other more common bacteria, actinomycetes, yeasts and fungi have also been isolated from different species of termites. This review summarizes the distinct role of the intestinal flora in degradation of wood components such as cellulose, hemicellulose and lignin.     

Molecular phylogenetic profiling of prokaryotic communities in guts of termites with different feeding habits

Termites are an important group of terrestrial insects that harbor an abundant gut microbiota, many of which contribute to digestion, termite nutrition and gas (CH(4), CO(2) and H(2)) emission. With 2200 described species, termites also provide a good model to study relationships between host diet and gut microbial community structure and function. We examined the relationship between diet and gut prokaryotic community profiles in 24 taxonomically and nutritionally diverse species of termites by using nucleic acid probes targeting 16S-like ribosomal RNAs. The relative abundance of domain-specific 16S-like rRNAs recovered from gut extracts varied considerably (ranges: Archaea (0-3%); Bacteria (15-118%)). Although Bacteria were always detectable and the most abundant, differences in domain-level profiles were correlated with termite diet, as evidenced by higher relative abundances of Archaea in guts of soil-feeding termites, compared to those of wood-feeding species in the same family. The oligonucleotide probes also readily distinguished gut communities of wood-feeding taxa in the family Termitidae (higher termites) from those of other wood-feeding termite families (lower termites). The relative abundances of 16S-like archaeal rRNA in guts were positively correlated with rates of methane emission by live termites, and were consistent with previous work linking high relative rates of methanogenesis with the soil (humus)-feeding habit. Probes for methanogenic Archaea detected members of only two families (Methanobacteriaceae and Methanosarcinaceae) in termite guts, and these typically accounted for 60% of the all archaeal probe signal. In four species of termites, Methanosarcinaceae were dominant, a novel observation for animal gut microbial communities, but no clear relationship was apparent between methanogen family profiles and termite diet or taxonomy.     

一株来源于海洋的抗肿瘤放线菌的分离鉴定

从福建东海海滩土样品中分离到一株海洋放线菌FIM02-523, 该菌株的发酵产物具有抗肿瘤活性。菌株FIM02-523在多数培养基上生长良好, 橙色-暗棕色, 无气生菌丝, 不产生可溶性色素。系统发育、化学分类特征、形态特征、生理生化特性等分析表明菌株FIM02-523是小单孢菌属(Micromonospora), 可能是模式菌种青铜小单孢菌(Micromonospora chalcea)的一个菌株。     

Detection of Mitochondrial COII DNA Sequences in Ant Guts as a Method for Assessing Termite Predation by Ants

Termites and ants contribute more to animal biomass in tropical rain forests than any other single group and perform vital ecosystem functions. Although ants prey on termites, at the community level the linkage between these groups is poorly understood. Thus, assessing the distribution and specificity of ant termitophagy is of considerable interest. We describe an approach for quantifying ant-termite food webs by sequencing termite DNA (cytochrome c oxidase subunit II, COII) from ant guts and apply this to a soil-dwelling ant community from tropical rain forest in Gabon. We extracted DNA from 215 ants from 15 species. Of these, 17.2 % of individuals had termite DNA in their guts, with BLAST analysis confirming the identity of 34.1 % of these termites to family level or better. Although ant species varied in detection of termite DNA, ranging from 63 % (5/7; Camponotus sp. 1) to 0 % (0/7; Ponera sp. 1), there was no evidence (with small sample sizes) for heterogeneity in termite consumption across ant taxa, and no evidence for species-specific ant-termite predation. In all three ant species with identifiable termite DNA in multiple individuals, multiple termite species were represented. Furthermore, the two termite species that were detected on multiple occasions in ant guts were in both cases found in multiple ant species, suggesting that ant-termite food webs are not strongly compartmentalised. However, two ant species were found to consume only Anoplotermes-group termites, indicating possible predatory specialisation at a higher taxonomic level. Using a laboratory feeding test, we were able to detect termite COII sequences in ant guts up to 2 h after feeding, indicating that our method only detects recent feeding events. Our data provide tentative support for the hypothesis that unspecialised termite predation by ants is widespread and highlight the use of molecular approaches for future studies of ant-termite food webs.     

Behavioral responses of two subterranean termite species (Isoptera: Rhinotermitidae) to instant freezing or chilling temperatures

The behavioral responses to instant freezing or chilling temperatures and survivorship of the Formosan subterranean termite, Coptotermes formosanus Shiraki, and the Eastern subterranean termite, Reticulitermes flavipes (Kollar), were studied using a novel experimental design that closely simulated subterranean termites' natural in-ground environment. Both termite species responded to changes in temperature by exhibiting a downward mass movement from the cold to warmer area of constant temperature. However, the degrees of response were specific to the species and temperature regimen. Approximately 88 and 96% of R. flavipes escaped from instant 0 degrees C and chilling regimens (from 24 to 0 degrees C at a rate of 1 degrees C/h or 1 degrees C/12 h), respectively, compared with approximately 77 and 91% of C. formosanus. No significant difference was detected between the two cooling regimens in either termite species. Controls resulted in a relatively even distribution within test tubes in both termite species. The small portion of the termites that did not escape endured a cold coma at a 24-h 0 degrees C and had low mortality of 2.2 and <1% in R. flavipes and <5.2 and <3% in C. formosanus at instant and chilling regimens, respectively. This result may have implications for understanding group intelligence and decision making evolved by subterranean termites to survive temporary freezing cold.     

白蚁及共生微生物木质纤维素水解酶的种类

白蚁是热带生态系统重要的木质纤维素降解者。白蚁种类丰富,可分成高等白蚁和低等白蚁,食性也具有各自特点。白蚁自身可以产生纤维素酶,主要是GHF9的内切葡聚糖酶(EG),也有β-葡萄糖苷酶(GB)。低等白蚁共生的原虫中已发现丰富的纤维素酶基因,属于GHF5,7和45。同时还有其他相关功能基因,如木聚糖酶和果胶类物质水解酶。高等白蚁肠道中没有共生原虫。高等培菌白蚁可以利用共生蚁巢伞属真菌促进木质纤维素降解,真菌可以产生纤维素酶,果胶质水解酶类、木聚糖酶,同时还产生可能与木质素分解相关的一种漆酶,但是从分子水平,关于共生真菌纤维素水解酶的研究还较少。白蚁肠道已分离出许多具有木质纤维素降解能力的菌株,最近的研究也发现了大量细菌纤维素酶基因。白蚁-共生系统丰富的木质纤维素水解酶类为发展生物方法开发纤维素乙醇这一思路提供有价值的资源。     

Iron reduction in the metal-rich guts of wood-feeding termites

Termites play important roles in lignocellulose and humus turnover in diverse terrestrial ecosystems, and are significant sources of global atmospheric methane and carbon dioxide. All known termite species engage in obligate, complex nutritional symbioses with their gut microbes to carry out such processes. Several hundred microbial species, representing a broad phylogenetic and physiological diversity, are found within the well‐bounded, microliter‐in‐scale gut ecosystem of a given termite. However, most of these species have never been obtained in laboratory culture, and little can be said about their functional roles in the gut community or symbiosis. Herein, an unappreciated facet of the gut chemistry and microbiology of wood‐feeding termites is revealed: the redox metabolism of iron. Gut fluids from field‐collected termites contained millimolar amounts of ferrous iron and other heavy metals. When iron(III) hydroxides were amended to a filter paper diet of Zootermopsis nevadensis, a dampwood termite collected in the San Gabriel Mountains of Southern California, the specimens accumulated high levels of iron(II) in their guts. Additionally, iron was reduced at rapid initial rates in anoxic gut homogenates prepared from field‐collected Z. nevadensis specimens. A Clostridium sp. and a Desulfovibrio sp. were isolated from dilution‐to‐extinction enrichments of Z. nevadensis gut contents and were found to reduce iron(III), as did the termite gut spirochete Treponema primitia. The iron in the guts of wood‐feeding termites may influence the pathways of carbon‐ and electron‐flow, as well as microbial community composition in these tiny ecosystems of global importance.     

New species of Actinoplanes cyanea sp. nov. and its antagonistic properties

An actinomycete stain 1569 isolated from a Siberian soil sample is described as a representative of a new species, designated as Actinoplanes cyaneus sp. nov. The actinomycete cell wall contains meso-diaminopimelic acid, arabinose, xylose and a non-identified analogue of diaminopimelic acid. The actinomycete forms spherical sporangia with mobile spores. The aerial mycelium is absent. The isolate produces a soluble blue pigment on synthetic media. The pygment investigation showed that it belonged to the group of celicomycin-actinorodine.     

一株根际放线菌的分离鉴定及其生物活性初探

从四川重庆药用植物蒿本根际土中分离到一株放线菌I06-02658,该菌株的发酵产物具有Caspase7抑制活性。菌株I06-02658在供试培养基上生长良好,形成丰富的基内菌丝,颜色从乳白到肉粉。在部分供试培养基上形成丰富的气生菌丝,产生浅黄至浅粉色可溶性色素。系统发育、化学分类特征、形态特征、生理生化特性等分析表明菌株I06-02658是糖霉菌属(Glycomyces)的一个菌株。     

A chitinolytic actinomycete complex in black soil

A chitinolytic actinomycete complex in chernozem soil has a specific taxonomic composition, which differs from that of the actinomycete complex which is typically isolated on standard nutrient media containing sugars and organic acids as carbon sources. The actinomycete complex that was isolated by using nutrient media with chitin as the source of carbon and nitrogen was dominated by representatives of the genus Streptosporangium, and the actinomycete complex that was isolated by using nutrient media with sugars and organic acids as the carbon sources was dominated by representatives of the genus Streptomyces. The confirmation to the ability of actinomycetes to utilize chitin as a sole source of carbon and nitrogen came from the augmented length and biomass of the mycelium, the increased number and biomass of the actinomycete spores, the production of carbon dioxide, and the accumulation of NH4+ ions in the culture liquid of the actinomycetes that are grown in the nutrient media with chitin.     

New producer of carminomycin, Actinomycer cremeospinus sp. nov.]

An actinomycete strain No. 85 was isolated from a soil sample on media with bleomycin. It was described as a representative of a new species. Actinomyces cremeospinus sp. nov. An antibiotic substance identical with carminomycin, an antitumor antibiotic was isolated from the culture fluid of the strain.     

Development of an efficient method for screening microorganisms by using symbiotic association between <Emphasis Type="Italic">Nasutitermes takasagoensis</Emphasis> and intestinal microorganisms

Screening method of microorganisms that utilized the symbiotic association between insect (Nasutitermes takasagoensis: Nt) and intestinal microorganisms was developed. The existence of desired microorganisms that grew by degrading difficult-to-degrade materials in the gut was detected using survivability of Nt as an indicator. The desired microorganisms were isolated from the survived Nt. It was thought that guts of Nt behave as continuous culture systems whereby microorganisms that cannot degrade diet components are washed out, whereas those that can degrade it are retained and concentrated in the gut. About 60% of Nt fed with phenol artificial diet (PAD) died within 7 days, while 4% of termites survived for 9 days. The structure of intestinal microorganisms of the survived Nt fed with PAD differed from the bacterial communities obtained from enrichment culture (which contained phenol) of wood-feeding Nt. Relatively high colonies (650-times) were detected in the gut of Nt fed on phenol artificial diet compared with those obtained when Nt was fed on wood. Seven denaturing gradient gel electrophoresis (DGGE) bands were detected from gut of wood-feeding Nt, whereas 11 DGGE-bands were detected from that of phenol-feeding Nt. Out of 11 DGGE-bands, 5 of them were sequenced, and bacterial species including phenol-degrading bacteria were identified.     

Studies on the distribution of alkalophilic and alkali-tolerant soil fungi II: Fungal flora in two limestone caves in Japan

In a series of studies on the distribution of alkalophilic and alkali-tolerant fungi, soil fungi were isolated from five alkaline calcareous soil samples in two closely located limestone caves (stalactite caves) in Japan using slightly acidic and alkaline media. Some common soil fungi that can grow in alkaline conditions were obtained in high frequencies. The growth response to pH of the isolates revealed that approximately one third (30.8%) of the isolates had the optimum pH in the alkaline range. All isolates of fourAcremonium species and twoChrysosporium species grew well in alkaline conditions, of whichAcremonium sp. andChrysosporium sp. were pronounced alkalophiles. These fungi were thought to be indigenous species in this alkaline environment. The fungal flora in the Japanese alkaline soils was considerably different from the flora reported in alkaline environments in other countries.     

Use of Genetically Engineered Escherichia coli to Monitor Ingestion, Loss, and Transfer of Bacteria in Termites

Escherichia coli was transformed with a recombinant plasmid (pEGFP) containing the genes for ampicillin resistance and Green Fluorescent Protein (GFP). Escherichia coli expressing GFP (E. coli/GFP+) was then fed to workers of the termite Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae). The transformed bacteria in the termite guts were detected by growing the gut flora under selective conditions and then checking the cultures for fluorescence. Recombinant plasmids in the termite gut were detected by plasmid extraction with subsequent restriction enzyme digest. The presence of the GFP gene in the gut of termites fed with E. coli/GFP+ was verified by PCR amplification. Transformed E. coli were ingested rapidly when workers fed on filter paper inoculated with E. coli/GFP+. After 1 day, 42% of termite guts harbored E. coli/GFP+. Transfer of E. coli/GFP+ from donor termites (fed with E. coli/GFP+) to recipients (fed with moist filter paper) occurred within 1 day. However, without continuous inoculation, termites lost the transformed bacteria within 1 week.     

1株新抑锈病素产生菌FIM03-1149的分离鉴别

在寻找新型抗真菌抗生素的过程中,从海洋放线菌FIM03-1149发酵液中分离到抗真菌抗生素新抑锈病素(Neorustmicin)。菌株FIM03-1149在多数培养基上生长良好,淡黄-橙黄色,无气生菌丝,不产生可溶性色素。形态特征、化学分类特征和生理生化特性等研究表明菌株FIM03-1149属于小单孢菌属。16SrRNA基因序列分析也表明菌株FIM03-1149属于小单孢菌属,但与最接近已知种Micromonospora siamensisTT2-4T处于不同的进化分支,2个菌株在某些生理生化特性上也有不同。基于上述数据,菌株FIM03-1149可能是小单孢菌属的1个新种。     

Nitrogen-fixing Enterobacter agglomerans isolated from guts of wood-eating termites.

Two strains of facultatively anaerobic, N2-fixing bacteria were isolated from guts of Coptotermes formosanus and identified as Enterobacter agglomerans. The deoxyribonucleic acid base composition of isolates was 52.6 and 53.1 mol% guanine plus cytosine. Both isolates and a known strain of E. agglomerans carried out a mixed acid type of glucose fermentation. N2 fixation by E. agglomerans was inhibited by O2; consequently, N2 served as an N source only for cells growing anaerobically in media lacking a major source of combined N. However, peptone, NH4Cl, or KNO3 served as an N source under either aerobic or anaerobic conditions. It was estimated that 2 x 10(2) cells of E. agglomerans were present per termite gut. This value was 100-fold lower than expected, based on N2 fixation, low recoveries of E. agglomerans may be related to the marked decrease in N2 fixation rates observed when intact termites or their extracted guts were manipulated for the isolation of bacteria. It was concluded that the N2-fixing activity of E. agglomerans may be important to the N economy of C. formosanus.     

A Chitinolytic Actinomycete Complex in Chernozem Soil

A chitinolytic actinomycete complex in chernozem soil has a specific taxonomic composition, which differs from that of the actinomycete complex typically isolated on standard nutrient media containing sugars and organic acids as carbon sources. The actinomycete complex that was isolated by using nutrient media with chitin as the source of carbon and nitrogen was dominated by representatives of the genus Streptosporangium, and the actinomycete complex that was isolated by using nutrient media with sugars and organic acids as the carbon sources was dominated by representatives of the genus Streptomyces. The confirmation of the ability of actinomycetes to utilize chitin as a sole source of carbon and nitrogen came from the augmented length and biomass of the mycelium, the increased number and biomass of the actinomycete spores, the production of carbon dioxide, and the accumulation of NH₄ ⁺ ions in the culture liquid of the actinomycetes grown in the nutrient media with chitin.     

Whole-Genome Sequence of Nocardiopsis alba Strain ATCC BAA-2165, Associated with Honeybees

The actinomycete Nocardiopsis alba was reportedly associated with honeybees in separate occurrences. We report the complete genome of Nocardiopsis alba ATCC BAA-2165 isolated from honeybee guts. It will provide insights into the metabolism and genetic regulatory networks of this genus of bacteria that enable them to live in a range of environments.