Bacterial communities in the waterlogged wooden cultural relics from the “Nanhai No. 1” shipwreck

Abstract:

[Objective] To understand the distribution of microorganisms and their effects on the waterlogged wooden relics collected from the "Nanhai No. 1" shipwreck. [Methods] Prokaryotic microorganisms in 10 wooden relics samples collected from the "Nanhai No. 1" shipwreck were identified by using high throughput sequencing technique. The composition and diversity of the bacterial communities in each sample were analyzed. [Results] Total 121 394 313 bacterial sequences with an average reading length of 458 bp were obtained. There were 3 780 different OTUs based on the similarity of the 97% sequences. According to the sequence in the GenBank database, 34 orders, 35 families and 187 genera of bacteria were involved in the wooded relics. Among these bacteria, most species were from Proteobacteria, and the species from Bacteroidetes ranked in the second. In the class level, the species from γ-Proteobacteria and α-Proteobacteria contributed more on community diversity. Hydrogenophaga, Lacibacter cauensis, Acidovorax delafieldii, Devosia, Sediminibacterium, Brevundimonas diminuta and Pseudomonas mendocina were found in all samples, and Muricauda, Thiobacillus, Rhodoplanes, Emticicia, Methylotenera mobilis and Flavobacterium were appeared with higher frequency of bacterial taxa. Principal component analysis showed that there were some differences in the composition of the bacterial community in different cultural relics. [Conclusion] There were rich biodiversity in prokaryotic microorganisms, both aerobic and anaerobic, in the archaeological wood from "Nanhai No. 1" shipwreck. The bacteria species, which participate in the decomposition of cellulose in the bacterial communities, resulted in a great challenge to the protection of cultural relics. At the same time, impact from iron-sulfur cycle bacteria should be taken into consideration due to they were existing in these relics.