Abstract

Nine chitin-degrading isolates of moderately thermophilic bacteria with temperature optimum for growth and chitin destruction at 50–55°C were isolated from soils of the New Athos Cave (Abkhazia). Four most active bacterial cultures with chitinase production yields 0.11–0.28 U mL^–1 (at 48°C) were screened from seven isolates forming aerial mycelium. Selected isolates were identified as Laceyella sp. species based on their cultural, morphological, physiological, and biochemical characteristics, as well as on phylogenetic analysis of their 16S rRNA gene sequences; these formed a cluster with L. sacchari, L. sediminis, and L. tengchongensis on the phylogenetic tree with sequence identity of 96.43–97.21%. Occurrence of isolated thermoactinomycetes in the cave was confined to tour circuit zones and the area inundated with flood waters. Laceyella spp. strains NAC-16-5 A-4 and NAC-16-5 A-5 degraded 85–100% of colloidal chitin (5 g L^–1) after 96 h of submerged cultivation (48°C). Inducible synthesis of chitinolytic enzymes was observed in all selected strains and reached its maximum in the presence of crab shell chitin. The enzymatic complex of Laceyella sp. NAC-16-5 A-4 was active in pH range 4–10.5 with two optima at pH 5.5 and 7.0. While crude chitinases of all studied strains exhibited maximal activity at 60–70°C with similar temperature optima (65°C), the enzyme complexes from strains NAC-16-5 A-2 and NAC-16-5 A-4 were most stable at 70°C.

中文翻译：

---

新型几丁质降解花边杆菌的特征。来自新阿索斯洞穴（阿布哈兹）的菌株产生热稳定的几丁质酶

摘要

从新阿索斯洞（Abkhazia）的土壤中分离了9种降解几丁质的嗜中性嗜热细菌分离株，它们的温度最适于生长和几丁质在50-55°C的破坏。从形成气生菌丝体的七个分离物中筛选出四种最活跃的几丁质酶产量为0.11-0.28 U mL ^-1（48°C）的细菌培养物。选定的菌株被鉴定为Laceyella sp.。根据其文化，形态，生理和生化特性以及对它们的16S rRNA基因序列的系统发育分析得出的物种；它们与糖乳杆菌（L. sacchari），塞氏乳杆菌（L. sediminis）和腾冲乳杆菌（L. tengchongensis）形成簇。在系统发育树上的序列同一性为96.43–97.21％。洞穴中孤立的热放线菌的发生仅限于巡回赛区域和被洪水淹没的区域。蕾丝菌属 NAC-16-5 A-4和NAC-16-5 A-5菌株在深水培养（48°C）96小时后降解了85-100％的胶质几丁质（5 g L ^–1）。在所有选定的菌株中均观察到了几丁质酶的诱导合成，在蟹壳甲壳质的存在下达到了最大值。蕾丝菌的酶复合物sp。NAC-16-5 A-4在4–10.5的pH范围内有活性，在pH 5.5和7.0时有两个最佳值。尽管所有研究菌株的粗壳多糖酶在60–70°C时均表现出最大活性，且最佳最佳温度（65°C）相似，但NAC-16-5 A-2和NAC-16-5 A-4菌株的酶复合物最多在70°C稳定。