The invention concerns a solid state fermenter in particular for
large volumes as well as a procedure for solid state fermentation.
The task of the present invention was the development of a solid
state fermenter for large volumes and of a procedure for solid state
fermentation, that allows an economic application of the solid state
fermentation for little competitive micro-organisms in large fermenters.
The solid state fermenter according to the invention is characterized
by representing a module fermenter, where at least two module bases,
that are permeable for air and water, are arranged on top of each
other, which are connected with the wall of the vessel in such a
manner, that neither air nor water can pass laterally, the existence
of a cultivation substrate for the micro-organisms, which have to
be cultivated, on the module bases, a cooling device below every
module base and the fermenter being closed with a lid.
What is claimed is:
1. A solid state fermenter comprising at least two module bases
that are permeable to air and water and that are arranged one above
the other, wherein the module bases contact a wall of the vessel
thereby preventing the lateral passage of water or air, the fermenter
further comprising on each of the module bases a cultivation substrate
suitable for cultivating microorganisms, and a cooling unit mounted
below each module base, and a lid.
2. The fermenter according to claim 1, wherein the fermenter comprises
a patent cylindrical, oval, rectangular or differently angular container
with at least one orifice (3) for the inoculum.
3. The fermenter according to claim 1, wherein metal plates with
a high thermal conductivity that protrude from the cooling device,
through the respective module base into the cultivation substrate.
4. The fermenter according to claim 1, wherein the existence of
a water supply (8) on the container, of an air-inlet (7) on the
bottom of the fermenter as well as of a water discharge (9) and
the existence of an orifice on the lid (1) for the outlet of air
(2), module bases (4) filled with cultivation substrate (5), that
were placed one after the other, for which rings or devices of different
shape (11) are mounted in the interior of the container for the
support of the module bases (4), that are equipped with a heat resistant
seal (10) and module bases having an edge (12), whose height depends
of the thickness of the layer of the cultivation substrate as well
as cooling devices (6) that are connected via a quick coupling (13)
with pipes (14) for discharge and supply of the cooling liquid,
which are outside of the fermenter.
5. The fermenter according to claim 4, wherein the mounting place
of the water supply (8) is in the bottom or in the lid of the fermenter.
6. The fermenter according to claim 1 wherein the lid comprises
an orifice for the inoculum and if necessary additional orifices
for the inoculation arranged between the single module bases.
7. The fermenter according to one of the claim 1, wherein the fermenter
containing several cylindrical, oval or prismatic containers, that
serve as modules, and that are arranged on top of each other in
such a way that the first container is supported below on the fermenter
bottom and that the last one is closed with a lid (1), and that
the containers are sealed from each other with heat resistant seals
(15) and are equipped with an exterior ring (16), the existence
of a base (4) that is permeable for air and water in each of the
containers, where the cultivation substrate (5) is located and below
which cooling device (6) is, which is connected by means of a coupling
(17) with the inflow and outflow pipes (14) for the cooling liquid,
that are outside of the fermenter.
8. The fermenter according to claim 1, wherein the cultivation
substrate being porous granulates with an added nutrient solution
or being natural granular materials.
9. The fermenter according to claim 8, wherein cereals, pellets
of bran or waste from the sugar production are natural granular
10. The fermenter according to claim 1, wherein the existence of
a moistening layer, which is at least on the lowest module base.
11. The fermenter according to claim 10, wherein the moistening
layer being a granular material capable of absorbing water with
an extremely high pore volume.
12. A procedure for solid state fermentation with a device according
to claim 1, wherein a cultivation substrate, which is in several
module bases in the fermenter, evenly inoculated, completely flowed
through by a relatively low air volume flow and for which the optimum
temperature is adjusted by means of the cooling system for the respective
13. The procedure according to claim 12, wherein a realization
of the inoculation with the micro-organism, which is to be multiplied
by filling up water in the fermenters, to which the germs are added
in a sufficient amount and in a manner, that all the layers are
evenly and flowed through during the filling as well as during the
14. The procedure according to claim 12, wherein the cooling capacity
is regulated in dependence of the volume of the cultivation substrate
in such a manner that the whole heat of reaction is evacuated from
BACKGROUND OF THE INVENTION
The invention concerns a solid-state fermenter in particular for
high volumes as well as a procedure for solid-state fermentation.
STATE OF THE ART
The submerged or solid-state fermentation is used for the mass
cultivation of microorganisms with the goal of either isolating
the microorganisms themselves or the metabolic product or a microbial
altered substrate (e.g. in the food-processing industry). Whereas
nowadays submerged fermenters (fermenters with a liquid nutritive
substrate) already are built with a capacity of up to 200.000 liters,
it has still not yet been achieved to build solid state fermenters
(fermenter with a solid nutritive substrate) with economically relevant
volumes, that can be kept free of contaminations by foreign micro-organisms
for longer periods and that allow an optimum in cultivation care
at the same time. However, certain filamentous fungi need surface
structures, which allow them to develop and sporulate there. The
largest fermenter for the production of filamentous fungi, which
avoids any foreign contamination is located in the INRA in France
(Durand 1997, verbal communication) and has a capacity of 50 liters.
However, the capacity of this fermenter is not at all sufficient
for an economic production of fungal spores that can be used, e.g.,
as biological agricultural pesticides.
The solid-state fermentation (SSF) is defined as growth of microorganisms--usually
fungi--on solid substrates in a defined gas phase, but without a
free water phase. SSF was already used for the production of fermented
food, of enzyme products (Koji) or of edible mushrooms in certain
territories of the Orient, Asia and Africa in the Ancient World.
The efforts in the Western countries were focused on the submerged
fermentation since 1940; whereas the SSF was only used for a reprocessing
of organic waste. However, many institutes and firms recently show
their interest in the SSF, because there are certain advantages
compared to the submerged fermentation. Such advantages compared
to the submerged fermentation are: Possibility of an effective production
of secondary metabolites such as enzymes, aroma substances, aromatic
substances and coloring substances as well as pharmaceutically active
substances Possibility of a production of microorganisms as biological
agents in agricultural pesticides Elimination of toxins or other
detrimental substances from food and feeding stuff or enrichment
of proteins or vitamins this stuff.
Fundamentally, there are 6 types of solid-state fermenters: 1.
tray bioreactor 2. packed bed bioreactor 3. rotary drum bioreactor
4. swing solid state bioreactor 5. stirred vessel bioreactor 6.
air solid fluidized bed bioreactor
The first type--the tray bioreactor--, where the substrate to be
fermented is spread out flatly in a container especially intended
for this purpose and that is incubated in a room, which is especially
air-conditioned for this reason (`Koji`--Raum, Ramana Murthy, M.
V.; Karanth, N. G.; Raghava Rao, K. S. M. S.: Advance in Applied
Microbiology 38 (1993), 99-147), can be used for the production
of large amounts of the product, however, it has to be possible
to neglect a small contamination by nucleus of crystallization by
this method. Moreover, reactor and method are very space- and labor-intensive.
The fermented substrate has to be moved manually within the containers.
It is not appropriate for the production of large amounts of fungal
spores of little competitive species.
In the `packed bed bioreactor` a moist granular substrate, which
is located in a closed container, is inoculated with a micro-organism,
which develops in there without the substrate being moved. For that
purpose, the substrate has to be perfused constantly by air. The
following problems occur, that do not allow the use of large amounts
of substrate from the beginning. 1. The micro-organism produces
heat (300 kJ per kg dry weight and hour, Saucedo-Castaneda, G.;
Gutierrez-Rojas, M.; Bacquet, G.; Raimbault, M.; Viniegra-Gonzalez,
G.: Biotechnologie and Bioengeniering 35 (1990), 802-808), which
can either be evacuated through the outer wall of the container
or through an increased air-circulation (evaporation coldness).
This is not possible, if the containers have large volumes. The
micro-organisms slow down their growth with an increase in heat
evolution and finally necrotize. 2. A constant aeration dries the
substrate out. Thus, the `loss` caused by this, creates air-channels.
Their existence cannot guarantee an even aeration of the substrate
any longer. The gradual drying out of the substrate also leads to
deterioration in growth of the micro-organism.
The `rotary drum bioreactor` consists of a cylindrical container,
which is allocated horizontally and pivoted. The container is filled
up to no more than one third of its volume with a granular cultivation
substrate, where the micro-organism grows. The heat generated by
the growth of the micro-organism can be evaporated to a large extent
by the partially cooled shell of the container. This happens during
the cylinder's slow rotation, which leads to the result, that the
substrate comes again and again into contact with the shell and
that it can evolve heat to it. However, the method has the disadvantage,
that shear forces have an effect within the moving substrate, which
lead especially to a destruction of fungal structures in development
(mycelium, sporangium, fructovegetative body). In this way, it is,
for example, for many fungi from the beginning not possible to obtain
the goal of a high yield in spores. The problem of exsiccation is
solved in this type of fermenter to a large extent by an aeration
with moist air, because it is not necessary to evaporate the water
from the substrate (evaporation coldness is not necessary). Moreover,
spray nozzles, could achieve a moistening of the substrate, too
providing a good distribution of free water by means of the movement.
However, large amounts of cultivation substrate lead to other problems
in this type of fermenter: 1. The design of large fermenters is
very costly. 2. The continuous movement of the fermenter can bring
about an agglomeration of the moist substrate. 3. Interfaces to
the exterior are necessary (air inlet and air outlet, water supply),
which could easily become sources of foreign contamination by the
rotation of the fermenter.
A similar fermenter as the `rotary drum bioreactor` is the `swing
solid state bioreactor`, with the only difference that the mixing
of the substrate is not caused by rotary movement here, but by a
shaking movement. Otherwise, the same, already mentioned advantages
and disadvantages apply. An additional limitation of the volume
for this type of fermenter is, however, applies, because the construction
of the complicated shaking mechanism would hardly allow a weight
of more than 100 kg for the filled container.
The `stirred vessel bioreactor` can be described as a closed tank
with a stirrer moving within. The problems for the use of large
amounts of substrate are inevitable for this type of reactor, as
these amounts can no longer be moved evenly without causing destructions
in the structure of the substrates.
The cultivation substrate for the micro-organisms is kept constantly
in a fluidized bed in the `air solid fluidized bed bioreactor`,
which makes a relatively large volume of the reactor room necessary.
The necessary air for keeping the fluidized bed up is conducted
in a circulation. The air must be kept with an exactly calculated
moisture content. This procedure requires a lot of energy for keeping
the fluidized bed up. It could be demonstrated in an AiF project
already conducted (Bahr, d.; Menner, M.: BIOforum 18 (1995), 16-21),
that the cultivation of yeast cells is possible in the fluidized
However, this was only achieved on a relatively small scale and
at with rather small yields in comparison to the submerged fermentation.
A cultivation of filamentous fungi on large amounts of granular
cultivation substrate (more than 100 kg per batch) over several
weeks with this technique is only possible at high costs, which
are out of court.
Other state-of-the-art fermenters are too small to gain with them
an economically profitable amount of fungal spores (EP-A1-0 683
815 and FR 85.08555), or it is not possible to exclude for a sufficient
fermenter capacity a contamination of the cultivation substrate
with nucleus of crystallization over a longer period of time (DE
SUMMARY OF THE INVENTION
Thus, the task for the present invention was to develop a SSF fermenter
for large volumes and to provide a procedure for solid-state fermentation,
which allows an economic application of the SSF of little competitive
microorganisms in large fermenters.
It has to: 1. avoid a foreign contamination of the fermenter (keeping
up of sterile conditions during the entire process of fermentation),
2. evacuate the heat, which is caused by the fungal metabolism without
an exsiccation of the substrate (by increased air flow and use of
the evaporation coldness), 3. avoid the occurrence of shear forces
in the fermenter (no movement of the cultivation substrate) and
4. guarantee an even aeration (avoiding the exsiccation) and control
over the temperature of the substrate.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1--principle drawing of the fermenter;
FIG. 2--cooling device of the fermenter with thermally conducting
FIG. 3--selection of a fermenter consisting of a patent cylinder;
FIG. 4--section of an assembled fermenter.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The task was solved according to the invention by a module fermenter,
which has a capacity of at least 50 liters, preferably 500 liters
to 1000 liters, but also allows higher capacities. The entire construction
consists of a cylindrical or oval vessel (FIG. 1), that can be closed
on top by a lid 1, which can be equipped, if necessary, with an
air outlet 2 as well as with an orifice 3 for the inoculation of
The vessel, which is constructed as a shell impermeable to air
and water, contains module bases 4 that are arranged in tiers and
are permeable to air and vapor, which are for taking up of a cultivation
substrate 5 for the micro-organisms to be cultivated.
The cultivation substrate consists of different materials according
to the respective nutrient requirement of the microorganism, which
has to be cultivated. This material preferably has a granular structure
in order to guarantee a sufficient permeability for air. It can,
for example, consist of cereals, pellets of bran or other organic
waste products, waste from the sugar production or granulates soaked
The number of tiers depends of the requirements of the cultivation
of the microorganism to be cultivated as well as of the ease of
servicing of the entire fermenter. Too many tiers could disturb
the necessary supply of oxygen for the growth of the microorganisms
(see below) in the upper layers of the cultivation substrate. Very
many tiers deteriorate the ease of servicing of the fermenter, too.
However, according to the invention, 20 or more tiers could be mounted
in the fermenter.
The module bases are connected to the wall of the vessel in such
a way, that neither air nor water can flow past them laterally.
The distance between the module bases depends of the optimum layer
thickness of the cultivation substrate, which is determined, on
the other hand, by the requirements of the microorganism to be cultivated.
There are cooling devices 6 located below the module bases, which
can be designed either as cooling coils or as cooling plates. They
allow the evacuation of the heat of the reaction from the cultivation
substrate. In a preferred variation, metal plates with a high thermal
conductivity can reach into the cultivation substrate through the
particular module base from each cooling device (FIG. 2). This makes
the evacuation of the heat of the reaction easier. After completion
of the fermentation process, the cooling device is pulled out together
with the cooling plates in downwards direction from the module base
for a removal of the cultivation substrate. Afterwards, it is possible
to take out the cultivation substrate with the grown microorganisms,
without an interference of the cooling plates.
It is also possible to mount the cooling devices in a certain distance
above the module bases. In this case, they should be installed in
such a manner, that they run in the middle of the layer of the cultivation
substrate. The installation of the cooling devices within the substrate
layers (parallel to the module bases) is especially to be included
in the case when very much heat of reaction is produced in the process
The base of the fermenter contains an air-inlet 7, where sterile,
moistened air is blown into the fermenter. The air circulates through
all layers of substrate and leaves the fermenter through the air-outlet
2 mounted on the lid.
The interstices located between the modules, which also house cooling
devices, guarantee an even distribution of the air in the entire
fermenter. If no moistened air is available for the aeration of
the fermenter, the air can also be moistened within the fermenter.
This is realized by not filling up at least the lowest module base
with a cultivation substrate, but with a granular material, which
can absorb water, which is circulated first with the blown-in air
before the air penetrates further into the fermenter. This moistens
the air. If a large amount of water is required for the microorganism
in development, several of such modules for moistening of the air
can be installed with certain distances in the fermenter. The amount
of air to be blown in depends of the oxygen requirement of the microorganism
to be cultivated. It can vary between 1 and 100 liters per hour
per liter of cultivation substrate.
The fermenter is filled with sterile water up to uppermost layer
of cultivation substrate for the inoculation of the cultivation
substrate with the microorganism to be cultivated after a sterilization
of its content. A water inlet 8 is mounted for that reason, which
has a sterile filter inserted. However, the water inlet can also
be installed in a different place of the fermenter (e.g. on the
lid). After the filling up, the inoculum is inserted through an
orifice 3 in the lid, which is intended for this. Such orifices
3 for the inoculation of the fermenter can also be mounted between
the single module bases especially if there are very many modules.
In the first case the distribution of the inoculum in the fermenter
is realized exclusively by letting out the water through an orifice
9 in the bottom of the fermenter, which is designed for this purpose.
The inoculum (suspension of micro-organisms) flows through all
layers of cultivation substrate in this kind and remains in a sufficient
amount with the adherent water on them. If there are to many layers,
which have to be circulated, an effect of dilution can occur in
dependence of the constitution of the cultivation substrate. This
means that the microorganisms will be filtered through the cultivation
substrate through which it has to circulate. Thus their concentration
in the water decreases the lower they are. In order to prevent this,
orifices for the insertion of the inoculum into the fermenter can
also be mounted between the module bases in another variation. Inoculum
can already inserted by their usage during the filling of the fermenter
with water, which is distributed then with the water flow, which
is directed upwards as well with the water flow, which is directed
The inoculum, which is used for the inoculation of the fermenter,
consists of a highly concentrated suspension of small germinable
units (preferably of spores, conidiospores or bacterial germs) of
the microorganisms to be cultivated.
Under the condition of an even and sufficient inoculation of the
inoculation vessel, the course of the cultivation (duration of the
cultivation and yield of the product) as well as the quality of
the cultivation product (e.g. fungal spores) mainly depends of the
parameters of the cultivation care. It consists primarily in letting
in moistened air and control of the temperature. The air volume
flow has to be adjusted to the capacity of the air sterile filter.
The control of the temperature in the fermenter is secured by the
use of the cooling device, which is installed in the fermenter.
The cooling capacity has to be designed in such a way, that it is
possible to evacuate all the heat of reaction from the cultivation
substrate and maintain an optimum temperature for the cultivation
of the microorganism. The necessary cooling capacity also depends
of the layer thickness and thus of the volume of the cultivation
substrate. The more cultivation substrate is available for the growth
of the microorganisms, the more heat of reaction is produced. That
is why both parameters have to be optimized. Target is a development
of the micro-organisms, that is as quick as possible, as well as
a high yield of product, where the products can be depending on
the aim of the fermentation, fungal spores, bacterial cells, enzymes,
antibiotics, coloring substances and other substances.
Two design variations of the fermenter according to the invention
Variation 1. (FIG. 3)
The fermenter consists of a patent cylinder or a prism, which are
tightly closed on the bottom. The cylinder (usually a circular cylinder)
or the prism can have a diameter of 1 m and more. Its height is
limited by the technical ease of servicing as well as by the possibility
of maintaining optimum conditions for the microorganisms, which
have to be calculated. It is possible to realize heights of 2 m
The module bases 4 filled with cultivation substrate 5 are inserted
from above in this cylinder or the prism. Rings, or in case of the
use of a prismatic housing, devices of a different shape 11, are
mounted in the interior of the container for the support of the
module bases. Every ring or differently shaped support device is
equipped with a heat resistant seal 10, e.g. of silicone, where
the module bases are put on with their outer edges, which provides
a seal between the module base and the vessel wall, that is impermeable
for air and water. It is possible to take out the rings or differently
shaped support devices from the housing. The cooling unit 6 below
the module base, which can consist e.g. of a cooling coil made of
copper, is connected by a quick coupling 13 with the pipes 14 to
the inlet and outlet of the cooling liquid, which are located outside
of the fermenter. Every module base is provided with an edge 12,
whose height is adjusted according to layer thickness of the cultivation
substrate. This avoids that the cultivation substrate falls into
the fermenter vessel and its pollution.
The fermenter is tightly closed on top with the lid 1. It is designed
as a pressure vessel and can be sterilized because of this by the
entrainment of hot vapor, which is under pressure. Therefore, it
is not necessary to use an autoclave.
Variation 2. (FIG. 4)
The fermenter consists of several cylinders or prisms always of
little height (preferably about 7-30 cm), that can have a circular,
oval, rectangular or another angular base. A bottom permeable for
air and water is in each case mounted in all the single cylinders
or prisms. The cooling device is located below the bottom, and on
the bottom is the substrate for the cultivation of the microorganisms.
The cylinders or prisms are used as modules 4 for the composite
fermenter. They are arranged on top of each other and sealed from
each other by heat resistant seals 15, which are located on the
edges. The first module lies flush below against the fermenter bottom,
and the last module is closed on top by the fermenter lid. Thus
the fermenter can be assembled preferably of 10 or more modules.
As it is difficult to design such a composite fermenter as a pressure
vessel, the sterilization of the fermenter and of the cultivation
substrate within is realized in an autoclave. Thus the height of
the fermenter is in the first place dependant of the capacity of
the autoclave that is available. As a result, it will have to be
limited in most cases to a volume of 500-1000 liters. During the
autoclaving the fermenter is still open, that means, the single
modules are slightly (approximately 5 mm) lifted from each other.
This allows a good feeding of the hot vapor into the interior of
the fermenter, which causes the sterilization. The fermenter is
closed tightly after the autoclaving. Every module is equipped with
an exterior ring 16, which is designed for overlapping the existing
gap between the modules, when the fermenter is opened, in order
to avoid a contamination of the fermenter with nucleus of crystallization
after the autoclaving and before the closing, i.e. when the fermenter
is taken out from the autoclave.
After the fermenter is closed the cooling devices 6, which are
located below the module bases are connected by a coupling 17 with
the pipes 14, which are used for the supply and drain of the cooling
In a preferred design variation a granular cultivation substrate,
where microorganisms shall develop, consists of a 5-6 cm thick layer.
Up to 10 of such layers are arranged on top of each other. The granular
cultivation substrate, which is arranged in layers, is each time
put on a perforated bottom and thus, on a bottom permeable for air,
below which is a cooling coil (wound copper pipe), which can be
used for evacuating the heat, that is generated in the substrate.
The supply of the sterile filtered air comes from below. The air
is forced to circulate all the modules (layers of cultivation substrate)
evenly, because of the lateral hermetic sealing, before it can leave
the fermenter again on the top end. On the lowest module base is
a water-saturated layer, preferably SERAMIS granulate, through which
the air is conducted moistening it in such a way.
The sterilization of the fermenter together with the already inserted
cultivation substrate is realized preferably by vapor, that is heated
up to 121.degree. C., preferably in autoclaves, whereas the single
modules are slightly lifted from each other during the autoclaving
process, thus allowing the hot vapor to intrude into the modules.
Further data: volume: 500 liters amount cultivation substrate: 250
liters air volume flow: 1500 liters per hour power of the cooling
system: 2.5 kW
Differently to the types used so far (swing solid state fermenter
or rotary fermenter), where a constant overturn of the cultivation
substrate has to be realized for a heat removal, aeration and water
supply, it is no longer necessary to move the substrate with the
use of the method according to the invention. The storage of the
cultivation substrate in tiers of layers, which are sheathed as
a whole by a closed shell provides the following advantages:
1. The own weight of the cultivation substrate does not lead to
a densification and as a result of that to a reduction of permeability
for air of it.
2. The installation of a cooling device below the single modules
allows an easier evacuation of the generated heat.
3. Due to a relatively small thickness of the modules as well as
the spaces between the modules an even aeration of the substrate
layers is guaranteed.
4. As the aeration of the substrate is only used for supplying
oxygen as well as for evacuating generated gases and not for the
cooling of the substrate, it is possible to work with a very low
air volume flow, which does no longer lead to an exsiccation of
the substrate a the air is moistened.
5. As it is no longer necessary to move the substrate, mechanical
destruction of fungal structures (sporangium, fructovegetative body
etc.) can be ruled out.
Mass Cultivation of beauveria brongniartii for the Purpose of Yielding
The fermenter used for the cultivation of beauveria brogniartii
has a capacity of about 50 liters. It has the shape of a cylinder
with a diameter of 30 cm and a height of 70 cm. The outer shell
of the fermenter is made of heat resistant glass. Eight modules
were mounted in the fermenter, whose bottoms consist of a stainless
screen with a screen aperture of 3 mm. The distance between the
module bases was 8 cm. The lower bottom was filled with a 6 cm thick
layer of SERAMIS granulate. The 7 modules arranged above contained
crushed barleycorns as cultivation substrate. The layer thickness
of the cultivation substrate was approximately 6 cm. In total 30
liters of cultivation substrate were used.
The fermenter was sterilized by an autoclave. For this purpose,
the content of the fermenter was heated by hot vapor to 121.degree.
C. for a period of half an hour. The lid of the fermenter was slightly
opened during the process of autoclaving in order to allow the permeation
of the vapor into the interior of the fermenter. It was closed immediately
The fermenter was filled over the uppermost layer of the cultivation
substrates with sterile water for the inoculation. A 500 cm.sup.2
capsule of the type S+S-EXELON PES 20/5 HC (Schleicher und Schuell,
Dassel) was used for this. After that, the inoculum was inserted
through an orifice in the lid designed for this purpose. The inoculation
of the fermenter occurred under a laminar box. The used inoculum
was a 100 ml of a conidium suspension with 1.times.10.sup.9 conidii
per ml. After the insertion of the inoculum over the upper layer
of the cultivation substrate, the water was drained through a valve
in the fermenter bottom. All the layers of substrate were contaminated
evenly with fungal conidii.
After the inoculation of the fermenter, it was incubated in a room
with a temperature of 20.degree. C. A connection to the air supply
as well as to the cooling system followed. The air volume flow during
the entire fermentation process was 150 liters per hour. Water was
used as cooling liquid with a supply temperature of 17.degree. C.
The control of the cooling was adjusted in such a way, that the
cooling liquid was pumped through the cooling coil, if 22.degree.
C. were exceeded in the cultivation substrate, until it had cooled
down again to 20.degree. C. In this way, an average substrate temperature
of about 21.degree. C. could be maintained during the entire time
of the cultivation.
The goal of the cultivation was a yield of as many fungal conidii
as possible. The glass sheathe of the fermenter allowed a very good
observation of the course of the cultivation. The entire cultivation
substrate was covered by a white mycelium after about 10 days. This
mycelium changed its appearance form the 13.sup.th day on because
of the build-up of conidii and of conidiophores. It changed to a
powdered structure. The fermenter had a clear decrease in metabolism
activity after about 19 days. The evolution of heat decreased, which
clearly reduced the cooling frequency. The cultivation substrate
was taken out 21days after the inoculation of the fermenter and
the conidii were extracted by a special filtration technique from
the cultivation substrate, which then was completely grown with
beauveria brogniartii. A total amount of 3.3.times.10.sup.13 conidii
could be extracted with the module fermenter.
LIST OF REFERENCE SIGNS 1 lid 2 air-outlet 3 fermenter 4 module
base permeable for air 5 cultivation substrate 6 cooling device
7 air-inlet 8 water supply 9 water discharge 10 heat resistant seal
11 support device for the module base 12 edge of the module base
13 quick coupling 14 pipe for the inflow and outflow of the cooling
liquid 15 heat resistant seal 16 exterior ring 17 coupling