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The development of industrial biotechnology has created an increasing demand for alkaline lipolytic enzymes with functional diversity. In this study, an alkaline soil metagenomic library was constructed to search for new lipolytic enzymes. Two novel gene encoded alkaline esterases(designated as estA and estB) were isolated by functional screening from the library. The estA gene consisted of 834 bp and coded for 277 amino acids with a molecular mass of 29998. Amino acid sequence homology analysis indicates that EstA belongs to α/β hydrolase fold family 4.4(abH4.4), with EstA being the smallest member of that family yet reported. The estB gene consisted of 1185 bp and encoded 394 amino acids with a theoretical molecular mass of 40090. Its conserved domain analysis shows that EstB belongs to the GDSL hydrolase superfamily. Both EstA and EstB exhibit only moderate identity(