红海榄根际土壤中短小芽孢杆菌菌株DH-11的鉴定及其抗菌活性的分析

Identification of a Bacillus Pumilus Strain DH-11 from the Rhizospheric Soil of Rhizophora Stylosa Griff and Its Antibacterial Activities Analysis

根据菌体的形态、生理生化特征以及16s rDNA序列分析结果,将一株分离自中国海南东寨港红树林保护区红海榄根际土壤的细菌菌株DH-11鉴定为芽孢杆菌属的短小芽孢杆菌(Bacillus pumilus strain DH-11)。菌株DH-11是一种革兰阳性短杆菌,大小约为(0.5～0.6)μm×(0.7～1.5)μm,卵圆形芽孢侧端生。其细胞中的主要脂肪酸为Iso-C15∶0和Anteiso-C15∶0,它们的含量占菌体总脂肪酸含量的47.49%和26.21%,其它脂肪酸还包括Iso-C17∶1(7.27%)、Anteiso-C17∶0(6.92%)、C16∶1 N Alcohol(3.45%)以及C16∶0(2.33%)等。与已报道的短小芽孢杆菌菌株B.pumilus ATCC 7061的不同之处在于:菌株DH-11不能利用木糖和甘露醇产酸,且硝酸盐还原呈阳性。进一步的研究显示:菌株DH-11在改良马铃薯培养基中培养时,获得的培养液及其提取浸膏不能抑制革兰阴性细菌Escherichia coli和Pseudomonas aeruginosus的生长,但对革兰阳性菌Staphylococcus epidermidis、Staphy-lococcus aureus、Bacillus subtilis和Sarcina lutea的生长具有一定的抑制作用:其中发酵液浸膏1和浸膏2对上述菌株的最低抑菌浓度(MIC)分别为500.0和250μg/mL,浸膏2还可抑制真菌Candida albicans的生长,其MIC为500μg/mL。

The bacterium strain DH-11 ,which was isolated from the rhizospheric soil of Rhizophora stylosa Griff in Dongzhai harbor mangrove forest conservation in China, was identified as Bacillus pumilus according to its morphology, physiological characters, and 16s rDNA sequence analysis. The cells of strain DH-11 were 0.7 - 1.5 μm long and 0.5 - 0.6 μm wide, and Gram-positive rods with a lateral side spore in each cell. Its major cellular fatty acids were iso-C15：0 and anteiso -C15：0, which were about 47. 49% and 26. 21% of the total cellular fatty acids ,respectively. Other fatty acids included iso-C17：1 （7.27%） ,anteiso-C17： 0（6.92% ）, C16：1 N alcohol（3.45% ） ,C16：0（2.33% ） ,etc. However,unlike the strain ofB. pumilus ATCC 7061 ,strain DH-11 could not grow in the medium with 7% NaCl and produce acid with D-Xylose and D-Mannitol, and the reaction of nitrate reduction was positive. The fermentation broth of this strain cultured in the modified potato medium showed apparently antibacterial activity against the Grampositive bacteria, such as Staphylococcus epidermidis, Staphylococcus aureus, Bacillus subtilis and Sarcina lutea, while it could not suppress the growth of Gram-negative bacteria, such as Escherichia coli and Pseudomonas aeruginosus. Further analysis showed the extract 1 and extract 2 from the fermentation broth could suppress the growth of Gram-negative bacteria with the minimal inhibition concentration（MIC） of 500 μg/mL and 250 μg/mL,respectively. At the same time,the extract 2 could also suppress the growth of Candida albicans with MIC of 500μg/mL.