Evaluation of temperature, pH and nutrient conditions in bacterial growth and extracellular hydrolytic activities of two Alicyclobacillus spp. strains.

Extremophile bacteria have developed the metabolic machinery for living in extreme temperatures, pH, and high-salt content. Two novel bacterium strains Alicyclobacillus sp. PA1 and Alicyclobacillus sp. PA2, were isolated from crater lake El Chichon in Chiapas, Mexico. Phylogenetic tree analysis based on the 16SrRNA gene sequence revealed that the strain Alicyclobacillus sp. PA1 and Alicyclobacillus sp. PA2 were closely related to Alicyclobacillus species (98% identity and 94.73% identity, respectively). Both strains were Gram variable, and colonies were circular, smooth and creamy. Electron microscopy showed than Alicyclobacillus sp. PA1 has a daisy-like form and Alicyclobacillus sp. PA2 is a regular rod. Both strains can use diverse carbohydrates and triglycerides as carbon source and they also can use organic and inorganic nitrogen source. But, the two strains can grow without any carbon or nitrogen sources in the culture medium. Temperature, pH and nutrition condition affect bacterial growth. Maximum growth was produced at 65 °C for Alicyclobacillus sp. PA1 (0.732 DO) at pH 3 and Alicyclobacillus sp. PA2 (0.725 DO) at pH 5. Inducible extracellular extremozyme activities were determined for β-galactosidase (Alicyclobacillus sp. PA1: 88.07 ± 0.252 U/mg, Alicyclobacillus sp. PA2: 51.57 ± 0.308 U/mg), cellulose (Alicyclobacillus sp. PA1: 141.20 ± 0.585 U/mg, Alicyclobacillus sp. PA2: 51.57 ± 0.308 U/mg), lipase (Alicyclobacillus sp. PA1: 138.25 ± 0.600 U/mg, Alicyclobacillus sp. PA2: 175.75 ± 1.387 U/mg), xylanase (Alicyclobacillus sp. PA1: 174.72 ± 1.746 U/mg, Alicyclobacillus sp. PA2: 172.69 ± 0.855U/mg), and protease (Alicyclobacillus sp. PA1: 15.12 ± 0.121 U/mg, Alicyclobacillus sp. PA2: 15.33 ± 0.284 U/mg). These results provide new insights on extreme enzymatic production on Alicyclobacillus species.