Epiphytic bacteria, Ulva lactuca, culture-based bioprospecting, genome of a producer bacteria of laccases. Evaluation of the enzymatic activity (Ulvano-lyase and laccase) in epiphytic bacteria of macroalgae of the species Ulva lactuca, present in the rocky coastline "La Punta de la Loma" (Santa Marta - Colombia)

Marine enzymes have characteristics of interest in various biotechnological processes, because, many are active under exceptional physicochemical conditions. In this sense, the epiphytic bacterial communities of macroalgae of the species U. lactuca are a promising source of novel enzymes produced by the bacteria to metabolize different substrates provided by the macroalgal surface. In this study, functional screening of two enzymes (ulvane-lyases and lacases) was performed on 90 epiphytic bacteria isolated from the surface of U. lactuca, collected in La punta de la Loma, Santa Marta (Colombian Caribbean). A total of 24 isolates were screened positive to laccase activity tested in three substrates (guaiacol, 2,6-DMP, and tannic acid), belonging to the genera Bacillus, Brevibacterium, Lysinibacillus, Pseudomonas, Shewanella, Vibrio, Alcaligenes, and Achromobacter. The assess for lyases did not show conclusive results regarding the production of this type of enzyme in the isolates of interest. In order to corroborate the presence of laccase-coding genes in the isolates obtained, the Achromobacter denitrificans EPI-24 strain was selected due to its bioremediation potential. The in silico confirmation of the presence of laccase was verified by the assembly and annotation of its genome. The results identified two gene products (Multicopper Oxidase and Multicopper Polyphenol Oxidase), which could be responsible for the laccase activity detected in the plate, demonstrating the potential of epiphytic bacteria of U. lactuca in the production of enzymes, which could present unique functional properties under more versatile and efficient conditions, compared to conventional lacases produced by terrestrial fungi.

海洋酶在诸多生物技术流程中具备应用价值，因其多数可在极端理化条件下保持催化活性。据此而言，石莼（U. lactuca）这一大型藻类的附生细菌群落，是新型酶类的潜在来源——这些酶由附生细菌产生，用以代谢大型藻类表面提供的各类底物。本研究对从哥伦比亚加勒比圣玛尔塔市拉洛马角采集的石莼（U. lactuca）表面分离得到的90株附生细菌，开展了针对Ulvan裂解酶与漆酶的功能筛选。最终共有24株分离株在以愈创木酚、2,6-二甲氧基苯酚（2,6-DMP）和单宁酸为底物的检测中呈现漆酶活性阳性，这些菌株分属于芽孢杆菌属、短杆菌属、赖氨酸芽孢杆菌属、假单胞菌属、希瓦氏菌属、弧菌属、产碱杆菌属以及无色杆菌属。针对裂解酶的检测并未在目标分离株中获得该类酶产生的确定性结果。为验证所获分离株中漆酶编码基因的存在，研究选取了具备生物修复潜力的脱氮无色杆菌（Achromobacter denitrificans）EPI-24菌株作为研究对象。通过对该菌株的基因组组装与注释，完成了漆酶存在的计算机模拟（in silico）验证。研究结果鉴定出两种基因产物——多铜氧化酶（Multicopper Oxidase）与多铜多酚氧化酶（Multicopper Polyphenol Oxidase），它们可能是平板检测中漆酶活性的来源，这证实了石莼（U. lactuca）附生细菌具备产酶潜力；与陆生真菌所产的传统漆酶相比，这类酶或可在更通用、高效的条件下展现独特的功能特性。