Recycling of the nitrogenous waste uric acid (UA) of wood-feeding termites by their gut bacteria is one of the significant aspects of symbiosis for the conservation of nitrogen sources. Diverse anaerobic UA-degrading bacteria comprising 16 species were isolated from the gut of eight termite species, and were assigned to Clostridia, Enterobacteriaceae, and low G+C Gram-positive cocci. UA-degrading Clostridia had never been isolated from termite guts. UA-degrading ability was sporadically distributed among phylogenetically various culturable anaerobic bacteria from termite guts. A strain of Clostridium sp., which was commonly isolated from three termite species and represented a probable new species in cluster XIVa of clostridia, utilized UA as a nitrogen source but not as a sole carbon and energy source. This feature is in clear contrast to that of well-studied purinolytic clostridia or previously isolated UA degraders from termite guts, which also utilize UA as a sole carbon and energy source. Ammonia is the major nitrogenous product of UA degradation. Various purines stimulated the growth of this strain when added to an otherwise growth-limiting, nitrogen poor medium. The bacterial species involved the recycling of UA nitrogen in the gut microbial community of termites are more diverse in terms of both taxonomy and nutritional physiology than previously recognized.

Genotyping based on variable-number tandem repeats (VNTR) is currently a very promising tool for studying the molecular epidemiology and phylogeny of Mycobacterium tuberculosis. Here we investigate the polymorphisms of 48 loci of direct or tandem repeats in M. tuberculosis previously identified by our group. Thirty-nine loci, including nine novel ones, were polymorphic. Ten VNTR loci had high allelic diversity (Nei's diversity indices > 0.6) and subsequently were used as the representative VNTR typing set for comparison to IS6110-based restriction fragment length polymorphism (RFLP) typing. The 10-locus VNTR set, potentially providing >2 ؋ 10 9 allele combinations, obviously showed discriminating capacity over the IS6110 RFLP method for M. tuberculosis isolates with fewer than six IS6110-hybridized bands, whereas it had a slightly better resolution than IS6110 RFLP for the isolates having more than five IS6110-hybridized bands. Allelic diversity of many VNTR loci varied in each IS6110 RFLP type. Genetic relationships inferred from the 10-VNTR set supported the notion that M. tuberculosis may have evolved from two different lineages (high and low IS6110 copy number). In addition, we found that the lengths of many VNTR loci had statistically significant relationships to each other. These relationships could cause a restriction of the VNTR typing discriminating capability to some extent. Our results suggest that VNTR-PCR typing is practically useful for application to molecular epidemiological and phylogenetic studies of M. tuberculosis. The discriminating power of the VNTR typing system can still be enhanced by the supplementation of more VNTR loci.Over a decade, the fingerprinting method based on restriction fragment length polymorphism (RFLP) of IS6110 insertion sequences has been established as the standard for typing strains of Mycobacterium tuberculosis. IS6110 RFLP fingerprinting is very powerful when it is used to classify M. tuberculosis isolates harboring a large number of IS6110 in their chromosomes (33). However, the prevalence of M. tuberculosis strains harboring no, single, or few copies of IS6110 in their chromosomes dramatically lowers the discriminating efficiency of the method (1). In this regard, many alternative RFLPbased fingerprinting methods, e.g., direct repeat (DR) and polymorphic GC-rich repetitive sequence RFLP fingerprinting, are supplementarily used for differentiation (10, 24). In addition, various methods based on PCR, for example, ligation-mediated PCR, mixed-linker PCR, double repetitive element PCR, and DR-based spoligotyping, were developed mainly in order to avoid the technical demand of RFLP (5, 11, 14, 21). However, most PCR-based methods displayed poor discrimination power compared to the standard IS6110 RFLP typing, whereas others were critically confronted with limitations with respect to reproducibility and reliability (16).Variable-number tandem repeats (VNTR), often referred to as micro-or minisatellite DNA, are ubiquitous in eukaryotes and humans. They have been extensiv...

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