This disclosure describes recombinant Megasphaera microbes designed to include increased consumption of acetate, increased carbon flux to butyryl-CoA and/or hexanoyl-CoA, increased production of butyrate and/or hexanoate, or a combination thereof, than a comparable control. This disclosure also describes methods that generally include growing such recombinant microbes under conditions effective for the recombinant microbes to consume greater amounts of acetate, produce increased amounts of butyryl-CoA and/or hexanoyl-CoA, produce increased amounts of butyrate and/or hexanoate, or a combination thereof.

Provided are mutants PHY1, PHY4 and PHY5 of a wild-type phytase APPA. After being treated for 10 min at 80° C., the residual enzyme activities of the mutants PHY1, PHY4 and PHY5 are respectively higher by 33.85%, 53.11% and 75.86% compared with that of APPA-M; after being treated for 5 min at 85° C., the residual enzyme activities of the mutants PHY1, PHY4 and PHY5 are respectively higher by 14.89%, 28.45% and 44.94% compared with that of APPA-M, and the heat resistance of these mutants is significantly higher than that of APPA-M.

Provided are a phytase mutant and a coding DNA molecule thereof, a vector, and a host cell. The phytase mutant comprises an amino acid sequence having at least 90% identity with SEQ ID NO: 3, and compared with SEQ ID NO: 3, and contains an amino acid substitution at at least one position selected from the group consisting of 36, 126, 211, 253, 258, and 266. The heat resistance of the mutant is significantly improved, thus facilitating the wide application of phytase in feed.

Provided are mutants PHY1, PHY4 and PHY5 of a wild-type phytase APPA. After being treated for 10 min at 80° C., the residual enzyme activities of the mutants PHY1, PHY4 and PHY5 are respectively higher by 33.85%, 53.11% and 75.86% compared with that of APPA-M; after being treated for 5 min at 85° C., the residual enzyme activities of the mutants PHY1, PHY4 and PHY5 are respectively higher by 14.89%, 28.45% and 44.94% compared with that of APPA-M, and the heat resistance of these mutants is significantly higher than that of APPA-M.

Provided are mutants PHY1, PHY4 and PHY5 of a wild-type phytase APPA. After being treated for 10 min at 80° C., the residual enzyme activities of the mutants PHY1, PHY4 and PHY5 are respectively higher by 33.85%, 53.11% and 75.86% compared with that of APPA-M; after being treated for 5 min at 85° C., the residual enzyme activities of the mutants PHY1, PHY4 and PHY5 are respectively higher by 14.89%, 28.45% and 44.94% compared with that of APPA-M, and the heat resistance of these mutants is significantly higher than that of APPA-M.

Provided are mutants PHY1, PHY4 and PHY5 of a wild-type phytase APPA. After being treated for 10 min at 80 C., the residual enzyme activities of the mutants PHY1, PHY4 and PHY5 are respectively higher by 33.85%, 53.11% and 75.86% compared with that of APPA-M; after being treated for 5 min at 85 C., the residual enzyme activities of the mutants PHY1, PHY4 and PHY5 are respectively higher by 14.89%, 28.45% and 44.94% compared with that of APPA-M, and the heat resistance of these mutants is significantly higher than that of APPA-M.