Apparatus for obtaining containers from a sheet material, said apparatus comprising: - an operating unit (12, 24) for processing said sheet material, said operating unit (12, 24) comprising an upper operating part (15, 31) for interacting with an upper face of said sheet material and a lower operating part (17, 32) for interacting with a lower face of said sheet material; - sterilising means (67, 68, 167, 168) for sterilising a space adjacent to said upper operating part (15, 31) and to said lower operating part (17, 32), so as to create a substantially aseptic environment (59, 159) above and below said sheet material; - said apparatus further comprising a shaft member (41, 70, 141) for moving said lower operating part (17, 32) and/or said upper operating part (15, 31), said shaft member (41, 70, 141) being slidable inside a tubular element (45, 76); characterized in that between said shaft member (41, 70, 141) and said tubular element (45, 76) there is defined an annular chamber supplied with a contamination-inhibiting fluid to prevent contaminating of said lower operating part (17, 32) and/or said upper operating part (15, 31) with possible contaminating substances that penetrate between said shaft member (41, 70, 141) and said tubular element (45, 76) and reach said substantially aseptic environment (59, 159), and in that said tubular element has an inlet conduit, that leads said contamination-inhibiting fluid into said annular chamber, and an outlet conduit that enables said contamination-inhibiting fluid to be evacuated from said annular chamber, wherein said inlet conduit and said outlet conduit have a first portion that extends in a transverse flange, an intermediate portion that extends in a tubular portion parallel to a longitudinal axis, and a second portion that extends in said tubular portion transversely to said longitudinal axis, such as to connect said intermediate portion with said annular chamber. - an operating unit (12, 24) for processing said sheet material, said operating unit (12, 24) comprising an upper operating part (15, 31) for interacting with an upper face of said sheet material and a lower operating part (17, 32) for interacting with a lower face of said sheet material; - sterilising means (67, 68, 167, 168) for sterilising a space adjacent to said upper operating part (15, 31) and to said lower operating part (17, 32), so as to create a substantially aseptic environment (59, 159) above and below said sheet material; - said apparatus further comprising a shaft member (41, 70, 141) for moving said lower operating part (17, 32) and/or said upper operating part (15, 31), said shaft member (41, 70, 141) being slidable inside a tubular element (45, 76); characterized in that between said shaft member (41, 70, 141) and said tubular element (45, 76) there is defined an annular chamber supplied with a contamination-inhibiting fluid to prevent contaminating of said lower operating part (17, 32) and/or said upper operating part (15, 31) with possible contaminating substances that penetrate between said shaft member (41, 70, 141) and said tubular element (45, 76) and reach said substantially aseptic environment (59, 159), and in that said tubular element has an inlet conduit, that leads said contamination-inhibiting fluid into said annular chamber, and an outlet conduit that enables said contamination-inhibiting fluid to be evacuated from said annular chamber, wherein said inlet conduit and said outlet conduit have a first portion that extends in a transverse flange, an intermediate portion that extends in a tubular portion parallel to a longitudinal axis, and a second portion that extends in said tubular portion transversely to said longitudinal axis, such as to connect said intermediate portion with said annular chamber.