Natucins were made from the CAMP of commensal bacteria, with the CAMP of Natucin C, D, F and P being from those of chicks, dairy cattles, fishes and pigs raised in a semi-wild state, respectively. The commensal bacteria were found to sequentially secrete CAMP and a protease to eliminate the over-produced CAMP when co-cultured with bacteria of another species, resulting in the in situ production of CAMP not enough to promote healthy growth under conditions of intensive management. The CAMP display similar physicochemical properties as follows:
(ⅰ) with molecular weight of about 6 kD（Fig. 5）.
Fig 5. Electrophoresis (SDS-PAGE) profiles. The Mw of CAMP included in Natucin C was 6.5 kD.
(ⅱ) tolerant to high temperature treatment (121℃ for 20 min） and digestion of proteases of animal origin, but sensitive to peptidases from environmental bacteria.
(ⅲ) still effective in inhibiting growth of E.coli.K12D31 resistant to antibiotics (eg. streptomycin)（Fig. 6）
Fig. 6. Comparison of inhibition zones for Natucin C（M1）, streptomycin sulfate（S）and lincomycin hydrochloride（H）. indicator, Ecoli K12D31 .
(ⅳ ) effective in inhibiting growth of both Gram-negative (Fig. 7) and Gram-positive (Fig. 8) bacteria, resulting in bacterial cell rupture and leakage of the cytoplasmic contents.
Fig. 7. Transmission electron microscope of Ecoli K12D31 exposed to Natucin C (left) and Natucin P (right).
Fig. 8. Transmission electron microscope of Staphyloccocus aureus ATCC25923 exposed to Natucin C (left) and Natucin P (right).