Instrument and method for transferring microbiological samples in a predeterminated gaseous environment

While transferring a portion of a microbiological culture medium from one receptacle to another by means of a needle disposed on a base, a flow of gas is directed from the base towards the needle to form a protective gaseous environment around the transferred culture medium portion.

The present invention relates to apparatus and a method for inoculating or 
transferring microbiological cultures. 
Stocks of bacteria are frequently cultured for medical or industrial 
purposes. Certain ones of these stocks require for survival and 
development a particular environment, especially as far as the ambient 
atmosphere is concerned. For example, certain stocks of bacteria are 
killed by the oxygen in the air. Therefore, while these bacterial cultures 
are transferred, particularly during inoculation, it is absolutely 
necessary to maintain a predetermined atmosphere around the transferred 
material. 
For this purpose, it has been proposed to use a fluid-tight handling 
chamber with a transparent wall and defining ports with gloves which 
permit an operator to manipulate instruments in the interior of the 
chamber. The chamber operates as a lock chamber and has means for control 
of its atmosphere. 
Operating in such a chamber from the outside is rather difficult. 
Furthermore, since the instruments must frequently be sterilized by heat, 
an electric heater must be mounted inside the chamber and this constitutes 
a source of heat which, in turn, requires cooling means or means for 
regenerating the atmosphere. 
It has also been proposed to make use of an installation with tubes 
directed to the culture medium and permitting the latter to be immersed in 
the desired atmosphere. But since it is necessary to provide a sufficient 
working space between the tubes and the culture medium, the protective gas 
also entrains ambient air, particularly in view of the turbulences due to 
the presence of the instruments in this working space. 
Furthermore, while the sample is transferred from one receptacle to 
another, it is exposed to the ambient atmosphere. 
It is the primary object of this invention to overcome these disadvantages 
and difficulties, and to enable the culture transfer to be effected in a 
desired atmosphere without recourse to fluid-tight operating chambers and 
to maintain the transferred sample in a protective gaseous environment 
during the entire transfer procedure from one receptacle to another. 
The above and other objects are accomplished according to the invention 
with an apparatus which comprises a needle for successively introducing a 
portion of a culture into different receptacles to transfer the culture 
from one receptacle to another receptacle, as base on which the needle is 
disposed and wherefrom it protrudes, and distributing means carried by the 
base and operable to direct a flow of gas along the needle to form a 
protective gaseous environment around the transferred portion of the 
culture. 
In accordance with another aspect of the present invention, microbiological 
cultures are inoculated or transferred by successively removing a portion 
of a culture from one receptacle by means of a needle disposed on a base, 
which includes the step of retracting the needle with the removed culture 
portion on an end of the needle from the one receptacle, and introducing 
the removed culture portion on the end of the needle into another 
receptacle to transfer the culture portion thereto, and directing a flow 
of gas from the base along the needle to provide a protective gaseous 
environment around the transferred portion of the culture while the needle 
is retracted from the one receptacle and the removed culture medium 
portion is introduced into the other receptacle.

Referring now to the drawing and first to FIG. 1, the illustrated apparatus 
is shown to comprise hand-held instrument 1 which includes needle 2 
disposed at a forward end of base 3. One form of this base is illustrated 
in FIG. 2 where it is shown to be constituted by hollow box 4 having inlet 
connection 5 at a rear end of the box. 
Illustrated box 4 is formed of three readily detachable parts 6, 7 and 8 
which are assembled by threaded connections 9 and 11. Filter 12 is mounted 
in box 4 and is arranged between front chamber 14 and rear chamber 13 
which is in communication with inlet connection 5 so that the filter is 
traversed by gas coming from the inlet connection. The filter is 
constituted by a removable filter unit disposed between two perforated 
disc 15 and 16 held in place between shoulders on center part 7 and the 
interior ends of parts 8 and 9 when the parts are screwed together. 
The inner end of needle 2 is positioned in axial bore 17 in front end 18 of 
the base and retained therein by set screw 19. 
As shown in FIGS. 2 and 3, distributing means is carried by base 3 and is 
operable to direct a flow of gas along needle 2 to form a protective 
gaseous environment around the transferred portion of the culture when the 
apparatus 1 is in use for inoculating or transferring microbiological 
cultures. The illustrated distributing means comprises a principal nozzle 
operable to expel the gas forwardly in a direction substantially parallel 
to needle 2, the nozzle being constituted by three longitudinal ducts 21 
in front section 18 of the base around the rear end of the needle to 
produce a gas flow 22 substantially parallel to the needle, as shown in 
FIG. 1. An auxiliary nozzle is operable to expel a flow of gas 24 
laterally at the rear end of the needle and is comprised of four radial 
ducts 23 in front end 18 of the base and positioned slightly behind the 
rear end of the needle (FIG. 2). 
A source of protective gas under pressure comprises a flask 27 holding the 
gas under pressure and having an output connected to a group of gas 
pressure regulators 28 in turn connected to valve 29 which may be 
push-controlled, for instance by a foot pedal, the output of the valve 
being connected to a gas flow meter 26. A flexible gas feed pipe 25 
connects inlet connection 5 to the flow meter. 
When the cock of the pressure regulator 28 is open and valve 29 is 
operated, the gas from flask 27 will enter into hollow base 3 through 
inlet connection 5, the flow of the gas being indicated by flow meter 26 
and being capable of being controlled by the pressure regulator. After the 
gas has traversed filter 12, it enters front chamber 14 whence it escapes 
in the form of an axial flow 22 and a lateral or radial flow 24 through 
ducts 21 and 23, respectively. These ducts serve as gas distributors 
assuring a protective gaseous environment around needle 2. 
In operating the illustrated apparatus for inoculating or transferring 
microbiological cultures, a portion of a culture is first removed from one 
receptacle 30 by means of needle 2 disposed on base 3, which includes the 
step of retracting the needle with the removed culture portion on an end 
of the needle from receptacle 30, and then introducing the removed culture 
portion on the end of the needle into another receptacle (not shown) to 
transfer the culture portion thereto, hand-held instrument 1 simply being 
moved from the one to the other receptacle. While needle 2 is retracted 
from receptacle 30 and the removed culture portion is introduced into the 
other receptacle, flow of gas 22 is directed from base 3 along needle 2 to 
provide a protective gaseous environment around the transferred portion of 
the culture. At the same time, the gas escaping through lateral ducts 23 
removes the air contained in receptacle 30. While the needle is retracted, 
the removed sample remains securely protected by gas curtain 22. The 
needle is then immersed into a second receptacle where the inoculation 
with the culture takes place still under the protection of principal gas 
flow 22 while auxiliary gas flow 24 also fills the second receptacle with 
the protective gas. In this manner, the inoculum remains protected during 
the entire transfer. 
In the modified base shown in FIG. 4, elongated hollow sleeve 31 
constitutes the base on which needle 2 is disposed and the sleeve has 
inlet connection 32 for the gas. Gas feed cartridge 33 containing the 
protective gas under pressure is detachably connected to inlet connection 
32 by a threaded joint. Ball valve 34 retains the gas under pressure in 
the cartridge, the ball of the valve being held in the closing position by 
compression spring 35. A valve operating element constituted by push rod 
36 is mounted in the interior of hollow sleeve 31 and exterior control 
member 37 constituted by a deformable hand lever operates push rod 36 to 
open the valve by axially moving the push rod against the ball of the 
valve and to permit gas under pressure to enter from cartridge 33 into 
hollow sleeve 31. The gas traverses filter 38 and enters into front 
chamber 39 of sleeve 31 whence it escapes through nozzle ducts in the same 
manner as described in connection with FIGS. 2 and 3. 
The position of cartridge 33 on inlet connection 32 may be controlled by 
nut 40 to regulate the maximum opening of the valve and the resultant gas 
flow. 
Obviously, the needle and the gas nozzles providing the protective gas flow 
around the needle may take various forms and, if desired, the base on 
which the needle is disposed may be part of a portable tool, such as a 
robot.