NOVELTY - A protein (I) with the activity of a lytic enzyme comprising one or more of the amino acid (aa) sequences (S1), (S5), (S6) or (S7) fully defined in the specification or their mutants or variants, is new.    USE - (I), optionally mixed with other lytic enzymes or bacteria that express (I), are useful for decomposing biological materials, e.g. gram-positive or -negative bacteria, yeast, nematodes, fungi, alga, cellulose, chitinase and/or murein. Typical applications are pretreatment of activated sludge (to improve anaerobic conversion), treatment of microbially contaminated surfaces, e.g. foods; conversion of solid fermentation residues to soluble products, and as additives to washing compositions to kill bacteria at below 40 degrees C.    ADVANTAGE - (I) has high lytic activity on Gram-negative species and good activity on Gram-positive species. It has greater lytic activity than enzymes from L. enzymogenes strains 495 or AL1.    DETAILED DESCRIPTION - A protein (I) with the activity of a lytic enzyme comprising one or more of the amino acid (aa) sequences (S1), (S5), (S6) or (S7) fully defined in the specification or their mutants or variants, where:    (1) AVPNGVNYVGXTSARTSXAGQAVXQARXYXENAKGYLNG (S1);    (2) T(F/D)WNA (S5);    (3) FA(E/C)NTPF (S6); and    (4) YTTW (S7).    INDEPENDENT CLAIMS are also included for the following:    (a) a mixture (A) of at least two proteins, each with the activity of a lytic enzyme, comprising (I) and at least one of the beta-lytic metallo-endopeptidase of Lysobacter enzymogenes or an alpha-lytic enzyme, from the same species, that includes the sequence (S3), or its mutant variants or derivatives, where (S3) is ANIVGLIEYSINNASLXS;    (b) bacteria able to produce and/or secrete (I);    (c) a nucleic acid (II) that encodes (I);    (d) a vector containing (II);    (e) a host cell containing the vector of (d);    (f) preparation of a protein, especially (I), having the activity of a lytic enzyme by growing the cells of (e), or the bacteria of (b);    (g) a protein (Ia) produced by method (f); and    (h) an antibody (Ab) that specifically recognizes and binds to (I) or (Ia).