l-Tyrosine, which is widely used in the medical field and the food and chemical industries, is a high-value-added compound. In this research, we explored the ability to synthesize l-tyrosine from pyruvate using a Pichia pastoris whole-cell biocatalyst with Symbiobacterium toebii tyrosine phenol lyase (TPL) displayed on the surface. The optimal enzymatic reaction conditions consisted of 1 M ammonium chloride, 125 mM phenol, 200 mM HEPES, pH 8.0, and 60 °C. Under optimal conditions, the conversion rate was 76.7% at 5 h and the maximum conversion rate was >80% at 8 h. We then analyzed the reuse of our biocatalyst in three batches. In a 10 mL reaction system, the conversion rate at 5 h was 79.1% for the first batch, 67.9% for the second batch, and 58.6% for the third batch. In conclusion, our biocatalyst can synthesize high-value-added l-tyrosine at high temperatures within a short period of time and can be easily reused several times.

Bisphenol A (BPA) and heavy metals are widespread contaminants in the environment. However, the combined toxicities of these contaminants are still unknown. In this study, the bioluminescent bacteria Vibrio qinghaiensis Q67 was used to detect the single and combined toxicities of BPA and heavy metals, then the joint effects of these contaminants were evaluated. The results show that chronic toxicities of chromium (Cr), cadmium (Cd), lead (Pb), arsenic (As), mercury (Hg), nickel (Ni), and BPA were time–dependent; in fact, the acute toxicities of these contaminants were stronger than the chronic toxicities. Furthermore, the combined toxicities of BPA and heavy metals displayed BPA + Hg > BPA + Cr > BPA + As > BPA + Ni > BPA + Pb > BPA + Cd in the acute test and BPA + Hg > BPA + Cd > BPA + As > BPA + Cd in the chronic test, which suggested that the combined toxicity of BPA and Hg was stronger than that of other mixtures in acute as well as chronic tests. Additionally, both CA and IA models underestimated the toxicities of mixtures at low concentrations but overestimated them at high concentrations, which indicates that CA and IA models were not suitable to predict the toxicities of mixtures of BPA and heavy metals. Moreover, the joint effects of BPA and heavy metals mainly showed antagonism and additive in the context of acute exposure but synergism and additive in the context of chronic exposure. Indeed, the difference in the joint effects on acute and chronic exposure can be explained by the possibility that mixtures inhibited cell growth and luminescence in chronic cultivation. The chronic toxicity of the mixture should be considered if the mixture results in the inhibition of the growth of cells.