Oceguera-Cervantes Alejandro, Carrillo-García Agustín, López Néstor, Bolaños-Nuñez Sandra, Cruz-Gómez M Javier, Wacher Carmen, Loza-Tavera Herminia
Departamento de Bioquímica, Facultad de Química, Universidad Nacional Autónoma de México, Cd. Universitaria, 04510 México, D.F. México.
Appl Environ Microbiol. 2007 Oct;73(19):6214-23. doi: 10.1128/AEM.01230-07. Epub 2007 Aug 10.
Two bacterial strains (BQ1 and BQ8) were isolated from decomposed soft foam. These were selected for their capacity to grow in a minimal medium (MM) supplemented with a commercial surface-coating polyurethane (PU) (Hydroform) as the carbon source (MM-PUh). Both bacterial strains were identified as Alicycliphilus sp. by comparative 16S rRNA gene sequence analysis. Growth in MM-PUh showed hyperbolic behavior, with BQ1 producing higher maximum growth (17.8 +/- 0.6 mg.ml(-1)) than BQ8 (14.0 +/- 0.6 mg.ml(-1)) after 100 h of culture. Nuclear magnetic resonance, Fourier transform infrared (IR) spectroscopy, and gas chromatography-mass spectrometry analyses of Hydroform showed that it was a polyester PU type which also contained N-methylpyrrolidone (NMP) as an additive. Alicycliphilus sp. utilizes NMP during the first stage of growth and was able to use it as the sole carbon and nitrogen source, with calculated K(s) values of about 8 mg.ml(-1). Enzymatic activities related to PU degradation (esterase, protease, and urease activities) were tested by using differential media and activity assays in cell-free supernatants of bacterial cultures in MM-PUh. Induction of esterase activity in inoculated MM-PUh, but not that of protease or urease activities, was observed at 12 h of culture. Esterase activity reached its maximum at 18 h and was maintained at 50% of its maximal activity until the end of the analysis (120 h). The capacity of Alicycliphilus sp. to degrade PU was demonstrated by changes in the PU IR spectrum and by the numerous holes produced in solid PU observed by scanning electron microscopy after bacterial culture. Changes in the PU IR spectra indicate that an esterase activity is involved in PU degradation.
从分解的软泡沫中分离出两种细菌菌株（BQ1和BQ8）。选择它们是因为它们能够在补充有商业表面涂层聚氨酯（PU）（Hydroform）作为碳源的基本培养基（MM）（MM-PUh）中生长。通过比较16S rRNA基因序列分析，这两种细菌菌株均被鉴定为嗜环脂芽孢杆菌属（Alicycliphilus sp.）。在MM-PUh中的生长呈现双曲线行为，培养100小时后，BQ1的最大生长量（17.8±0.6 mg.ml⁻¹）高于BQ8（14.0±0.6 mg.ml⁻¹）。对Hydroform进行核磁共振、傅里叶变换红外（IR）光谱和气相色谱 - 质谱分析表明，它是一种聚酯型PU，还含有N - 甲基吡咯烷酮（NMP）作为添加剂。嗜环脂芽孢杆菌属在生长的第一阶段利用NMP，并能够将其用作唯一的碳源和氮源，计算得出的K(s)值约为8 mg.ml⁻¹。通过使用差异培养基和在MM-PUh中细菌培养物的无细胞上清液中的活性测定来测试与PU降解相关的酶活性（酯酶、蛋白酶和脲酶活性）。在培养12小时时，观察到接种的MM-PUh中酯酶活性的诱导，但未观察到蛋白酶或脲酶活性的诱导。酯酶活性在18小时达到最大值，并在分析结束（120小时）前一直维持在其最大活性的50%。通过PU红外光谱的变化以及细菌培养后扫描电子显微镜观察到的固体PU中产生的大量孔洞，证明了嗜环脂芽孢杆菌属降解PU的能力。PU红外光谱的变化表明酯酶活性参与了PU的降解。
