湖南益阳兔子山遗址出土竹简浸泡液可培养细菌的分离鉴定及部分功能特性

Isolation,identification,and functional characteristics of cultural bacteria in waterlogged bamboo slips unearthed from Tuzishan site in Yiyang,Hunan Province

出土竹简失水后易导致其收缩变形,因而采用了不同措施对竹简进行饱水保存,但在饱水保存期间竹简仍可能遭受微生物的侵蚀而损害.为制定科学、适宜的饱水保存方案,采用稀释涂平板法获得可培养菌株,通过菌株形态学及16S rRNA基因测序,对其进行系统发育分析,并结合菌株纤维素、木质素降解酶活测定及木材崩解实验,对其进行降解潜力分析,比较益阳兔子山遗址出土竹简不同保存状态浸泡液中的细菌群落结构与功能特征.结果显示,加入新洁尔灭抑菌剂的竹简浸泡液(CX)可培养细菌含量最低,而使用长试管保存的竹简浸泡液(CS)含量最高,出现明显变色的竹简浸泡液(CB)与无明显变化的竹简浸泡液(CQ)含量差异较小;共分离获得13株细菌,分属于伯克霍尔德菌属(Burkholderia)、假单胞属(Pseudomonas)、微杆菌属(Microbacterium)、贪铜菌属(Cupriavidus)、新鞘脂菌属(Novosphingobium)及Paraburkholderia 6个属,其中CX样品种群较丰富;纤维素、木质素降解功能筛选结果显示,具有降解能力的6株菌株均分离自CX、CS样品,其酶活在1.0-9.0 U/mL范围;6株具有降解酶活的菌株其竹材降解率均大于10%,在10.5%-16.5%范围.本研究表明不同保存方式的竹简浸泡液中细菌种群结构具有一定差异,其中还存在对饱水竹简具有潜在降解危害的微生物.因此,建议根据出土竹简的具体状况,采用适合的保存方式,并添加复合抑菌剂防止微生物损害饱水竹简.

To identify an effective storage approach for the preservation of bamboo slips,we studied the bacterial community structure and function of the soak solution of the waterlogged bamboo slips unearthed from a Han dynasty tomb located in Tuzishan of Yiyang,Hunan province.To avoid the deformation of bamboo slips due to water loss and shrinkage,different preservation measures can be undertaken.However,the waterlogged bamboo slips we found were probably spoilt by microbial attack.Culturable strains were isolated using the spread plate method,and the phylogenetic level of the isolates was analyzed based on morphological characteristics and 16S rRNA gene sequencing.The potential degradation of these strains was analyzed based on the activities of cellulose-and lignin-degrading enzymes and wood disintegration experiments.Results showed the number of bacteria in the sample with added bromo-geramine(CX)was lower than that in the other samples,while samples preserved in the long glass tube(CS)had the most diverse community;importantly,there was little difference between the sample with the color turning yellow(CB)and sample without obvious change(CQ).Thirteen strains were isolated using the culture-dependent method,belonging to the Burkholderia,Pseudomonas,Microbacterium,Cupriavidus,Novosphingobium,and Paraburkholderia genera;the community of sample CX was richer.The results showed that six strains isolated from CX and CS samples could degrade cellulose or lignin,and their enzymatic activities ranged from 1.0 to 9.0 U/mL.The efficiency of bamboo degradation by the six strains was higher than 10%,ranging from 10.5%to 16.5%.The bacterial community structure and function under different preservation conditions of waterlogged bamboo slips varied,and some isolates had potential degradation functions.Based on the above results,we suggest employing appropriate preservation measures and adding compound antimicrobial agents to the soak solution to avoid microbial attack.