de Almeida Couto Camila Rattes, Alvarez Vanessa Marques, Marques Joana Montezano, de Azevedo Jurelevicius Diogo, Seldin Lucy
Laboratório de Genética Microbiana, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Centro de Ciências da Saúde, Bloco I, Ilha do Fundão, Rio de Janeiro, RJ, CEP 21941-590, Brazil.
BMC Microbiol. 2015 Oct 28;15:240. doi: 10.1186/s12866-015-0575-5.
Biosurfactants are surface-active biomolecules with great applicability in the food, pharmaceutical and oil industries. Endospore-forming bacteria, which survive for long periods in harsh environments, are described as biosurfactant producers. Although the ubiquity of endospore-forming bacteria in saline and hypersaline environments is well known, studies on the diversity of the endospore-forming and biosurfactant-producing bacterial genera/species in these habitats are underrepresented.
In this study, the structure of endospore-forming bacterial communities in sediment/mud samples from Vermelha Lagoon, Massambaba, Dois Rios and Abraão Beaches (saline environments), as well as the Praia Seca salterns (hypersaline environments) was determined via denaturing gradient gel electrophoresis. Bacterial strains were isolated from these environmental samples and further identified using 16S rRNA gene sequencing. Strains presenting emulsification values higher than 30 % were grouped via BOX-PCR, and the culture supernatants of representative strains were subjected to high temperatures and to the presence of up to 20 % NaCl to test their emulsifying activities in these extreme conditions. Mass spectrometry analysis was used to demonstrate the presence of surfactin.
A diverse endospore-forming bacterial community was observed in all environments. The 110 bacterial strains isolated from these environmental samples were molecularly identified as belonging to the genera Bacillus, Thalassobacillus, Halobacillus, Paenibacillus, Fictibacillus and Paenisporosarcina. Fifty-two strains showed emulsification values of at least 30%, and they were grouped into 18 BOX groups. The stability of the emulsification values varied when the culture supernatants of representative strains were subjected to high temperatures and to the presence of up to 20% NaCl. The presence of surfactin was demonstrated in one of the most promising strains.
The environments studied can harbor endospore-forming bacteria capable of producing biosurfactants with biotechnological applications. Various endospore-forming bacterial genera/species are presented for the first time as biosurfactant producers.
生物表面活性剂是一类具有表面活性的生物分子，在食品、制药和石油工业中具有广泛的应用前景。能够形成芽孢的细菌可在恶劣环境中长时间存活，被认为是生物表面活性剂的生产者。尽管在盐碱和高盐环境中广泛存在能够形成芽孢的细菌已为人所知，但关于这些生境中形成芽孢并产生生物表面活性剂的细菌属/种的多样性研究却相对较少。
在本研究中，通过变性梯度凝胶电泳确定了来自Vermelha泻湖、马桑巴巴、多伊斯里奥斯和阿布拉昂海滩（盐碱环境）以及普拉亚塞卡盐场（高盐环境）的沉积物/泥浆样本中形成芽孢的细菌群落结构。从这些环境样本中分离出细菌菌株，并通过16S rRNA基因测序进一步鉴定。将乳化值高于30%的菌株通过BOX-PCR进行分组，并对代表性菌株的培养上清液进行高温处理以及在高达20% NaCl存在的条件下测试其在这些极端条件下的乳化活性。采用质谱分析来证明表面活性素的存在。
在所有环境中均观察到了多样的形成芽孢的细菌群落。从这些环境样本中分离出的110株细菌菌株经分子鉴定属于芽孢杆菌属、嗜盐芽孢杆菌属、盐芽孢杆菌属、类芽孢杆菌属、假芽孢杆菌属和类芽孢八叠球菌属。52株菌株的乳化值至少为30%，它们被分为18个BOX组。当代表性菌株的培养上清液经受高温以及在高达20% NaCl存在的条件下时，乳化值的稳定性有所不同。在其中一株最具潜力的菌株中证明了表面活性素的存在。
所研究的环境中可能存在能够产生具有生物技术应用价值的生物表面活性剂的形成芽孢的细菌。首次展示了多种形成芽孢的细菌属/种作为生物表面活性剂生产者的情况。
