Bauer S, Tholen A, Overmann J, Brune A
Institut für Chemie und Biologie des Meeres, Universität Oldenburg, Germany.
Arch Microbiol. 2000 Feb;173(2):126-37. doi: 10.1007/s002039900120.
Lactic acid bacteria have been identified as typical and numerically significant members of the gut microbiota of Reticulitermes flavipes and other wood-feeding lower termites. We found that also in the guts of the higher termites Nasutitermes arborum (wood-feeding), Thoracotermes macrothorax, and Anoplotermes pacificus (both soil-feeding), lactic acid bacteria represent the largest group of culturable carbohydrate-utilizing bacteria (3.6-5.2x10(4) bacteria per gut; 43%-54% of all colonies). All isolates were coccoid and phenotypically difficult to distinguish, but their enterobacterial repetitive intergenic consensus sequence (ERIC) fingerprint patterns showed a significant genetic diversity. Six different genotypes each were identified among the isolates from R. flavipes and T. macrothorax, and representative strains were selected for further characterization. By 16S rRNA gene sequence analysis, strain RfL6 from R. flavipes was classified as a close relative of Enterococcus faecalis, whereas strain RfLs4 from R. flavipes and strain TmLO5 from T. macrothorax were closely related to Lactococcus lactis. All strains consumed oxygen during growth on glucose and cellobiose; oxygen consumption of these and other isolates from both termite species was due to NADH and pyruvate oxidase activities, but did not result in H2O2 formation. In order to assess the significance of the isolates in the hindgut, denaturing gradient gel electrophoresis was used to compare the fingerprints of 16S rRNA genes in the bacterial community of R. flavipes with those of representative isolates. The major DNA band from the hindgut bacterial community was further separated by bisbenzimide-polyethylene glycol electrophoresis, and the two resulting bands were sequenced. Whereas one sequence belonged to a spirochete, the second sequence was closely related to the sequences of the Lactococcus strains RfLs4 and TmLO5. Apparently, those isolates represent strains of a new Lactococcus species which forms a significant fraction of the complex hindgut community of the lower termite R. flavipes and possibly also of other termites.
乳酸菌已被鉴定为黄胸散白蚁和其他以木材为食的低等白蚁肠道微生物群中的典型且数量可观的成员。我们发现，在高等白蚁如树鼻白蚁（以木材为食）、大胸象白蚁和太平洋无齿象白蚁（均以土壤为食）的肠道中，乳酸菌也是可培养的利用碳水化合物细菌中的最大群体（每个肠道中有3.6 - 5.2×10⁴个细菌；占所有菌落的43% - 54%）。所有分离株均为球状，在表型上难以区分，但其肠杆菌重复基因间共有序列（ERIC）指纹图谱显示出显著的遗传多样性。在黄胸散白蚁和大胸象白蚁的分离株中分别鉴定出六种不同的基因型，并选择代表性菌株进行进一步表征。通过16S rRNA基因序列分析，黄胸散白蚁的菌株RfL6被归类为粪肠球菌的近亲，而黄胸散白蚁的菌株RfLs4和大胸象白蚁的菌株TmLO5与乳酸乳球菌密切相关。所有菌株在葡萄糖和纤维二糖上生长时都会消耗氧气；这些以及来自两种白蚁的其他分离株的氧气消耗是由于NADH和丙酮酸氧化酶的活性，但不会导致过氧化氢的形成。为了评估这些分离株在肠道后端的重要性，采用变性梯度凝胶电泳比较黄胸散白蚁细菌群落中16S rRNA基因的指纹图谱与代表性分离株的指纹图谱。通过双苯甲酰亚胺 - 聚乙二醇电泳进一步分离来自肠道后端细菌群落的主要DNA条带，并对产生的两条条带进行测序。其中一个序列属于螺旋体，第二个序列与乳酸乳球菌菌株RfLs4和TmLO5的序列密切相关。显然，这些分离株代表了一种新的乳酸乳球菌物种的菌株，它在低等白蚁黄胸散白蚁以及可能其他白蚁的复杂肠道后端群落中占很大比例。
