WO2004016074A2

WO2004016074A2 - Mycoculture bottle cap filter assembly for use in bottle-based mushroom cultivation systems

Info

Publication number: WO2004016074A2
Application number: PCT/US2003/025541
Authority: WO
Inventors: Malcolm Clark; Thomas C. Hansen
Original assignee: Gourmet Mushrooms Inc.
Priority date: 2002-08-14
Filing date: 2003-08-14
Publication date: 2004-02-26
Also published as: AU2003259844A8; AU2003259844A1; WO2004016074A3

Abstract

An improved mycoculture bottle cap filter assembly for use in bottle-based mushroom cultivation systems, including a gasket (12) having surface structure on its upper surface (12a), wherein the gasket is interposed between the interior ledge (18) of a conventional mushroom bottle cap base (20) and the under structure of a bottle cap cover top (24). Microporous filter material (14) spanning the interior area of the gasket is securely held by the gasket (12) in the bottle cover cap. When the gasket and filter material are installed in a bottle cover cap on a mushroom cultivation bottle, the gasket surface structure engage the understructure of the bottle cap cover so as to create air passages (38) that allow for gas exchange between the mushroom cultivation bottle interior and the atmosphere, while simultaneously preventing the passage of destructive pests.

Description

MYCOCULTURE BOTTLE CAP FILTER ASSEMBLY

FOR USE IN BOTTLE-BASED

MUSHROOM CULTIVATION SYSTEMS

BACKGROUND OF THE INVENTION

Technical Field The present invention relates generally to caps for bottles, and more particularly to an improved mycoculture bottle cap filter assembly for use in mycoculture, and still more particularly to an improved bottle cap filter assembly for use in bottle-based mushroom cultivation systems.

Background Art

Until quite recently, mushroom cultivation relied heavily on a supply of a few different species of oak tree, including Quercus serrata and Quercus acutissima, and a species of beech, Fagus crenata, commonly referred to as Japanese beech. These trees (and other less preferable species) were used (and continue to be used) in what is known as the bed-log method of cultivating mushrooms. There are numerous disadvantages to employing this cultivation system. Firstly, the quality of the harvest is a function of the weather. Secondly, there is an increasing shortage of suitable bed logs. Thirdly, the cultivation period is relatively long, comprising roughly eighteen months to two years from inoculation to harvest. And fourthly, the system is labor intensive and generally not amenable to systematization and automation.

To overcome the problems of the bed log method, a bottle-based sawdust-medium system for mushroom cultivation was developed. Presently, several species of mushroom are now successfully cultivated in polypropylene bottles, including, among others, Flarnmulina velutipes, Pleurotus ostreatus, Hypsicygus tessulatus and Pholiota nameko. A very general outline of the method steps includes: selecting a medium, typically sawdust and/or sawdust with an additive, such as grain bran; adding water to bring the water content of the medium to a desired level; partially filling a polypropylene bottle with the medium and pressing and shaping it to accept an inoculation of spawn; stoppering the bottle with a bottle cap; autoclaving the bottle for a time sufficient to effectively sterilize it and the medium; cooling the bottle and medium; adding a spawn of a single species of mushroom; cultivating the mycelium in species-specific environmental conditions for a period of time sufficient to permit mycelium to colonize the medium and thereafter cultivating the mycelium for an additional period of one month or more months; removing the cap and preparing the surface of the medium to promote fruiting bodies; adding water if necessary; removing excess water after a predetermined period of time has passed; continuing cultivation under controlled temperature, humidity, and light to form primordia of fruiting bodies; and finally increasing the light intensity and cultivating the fruiting bodies to harvest.

This method provides uniformity and continuity in harvests and it provides a system that lends itself to automation and mass production. The mushroom industry has therefore moved in the direction of adopting the bottle-based sawdust medium method of mushroom cultivation. However, the bottle-based method is not without problems, foremost among them being vulnerability to infestation from mites.

Mites are not insects; rather, they are close relatives of ticks, spiders, scorpions, and harvestmen, and they constitute the subclass Acari, part of the arthropod class Arachnida.

Mite larvae generally have three pairs of legs, while nymphs and adults have four pairs. Depending on their family, they may be nude, covered with setae, or by a few or many hardened plates or shields.

Mites are the most diverse and abundant of the Acarina, but because of their small size, they are rarely seen. The largest are slightly more than 30 millimeters in length, the smallest only 0.1 millimeter in length. Most are virtually invisible to the unaided eye, though they can be detected when viewed on contrasting dark background. Red velvet mites, a giant among mites, can be found when hunting on the ground or on or near tree trunks. By contrast, the human follicle or the honeybee tracheal mite are small enough to breed within a human hair follicle or within a bee's respiratory tube. Water mites are so brightly colored that they may be seen as they rapidly move about.

Mites are of economic significance to humans. There are several plant-feeding and soil-residing species that affect the mushroom industry, though the oribatid or beetle mites are most significant. They cause untold economic damage to commercial mushroom growers. Patents disclosing illustrative systems for bottle-based mushroom cultivation include, inter alia, U.S. Pat. No. 6,334,274, to Inoue, et al, which discloses a method of sawdust- based cultivation shitake (Cortinellus shitake), including the steps of mixing saw-dust of a broad-leaved tree and wheat bran; adding water into the mixed saw-dust and wheat bran to make a mixture; introducing the mixture into a filtered culture container of polypropylene plastic to make a substrate; steam-sterilizing the culture container and the mixture; inoculating the sawdust-based substrate with mushroom spawn; cultivating the substrate at room temperature to form a brown spawn layer on a surface of the substrate, whereby mushroom fruiting bodies are formed; and harvesting said fruiting bodies. In this method, the number of cultivated primordia are decreased by temporarily elevating the temperature into a zone between 20 degree C. and 40 degree C. during/between the cultivation step and the growing step.

United States Pat. No. 4,674,228, to Murata , et al., teaches a process for preparing artificial bed blocks for "Shiitake" mushroom cultivation, comprising culturing lumps of spawn (mycelia) in a bottle, taking out the grown-up mycelia from the container to be kept in a closed space, keeping culturing while raising humidity in the space close to saturation to form a new aerial hypha layer on the whole surface of the lumps of spawn for higher resistance to weed fungi, then sprinkling with water over the lumps in open space to prevent weed fungi from depositing.

As concerns bottle-based mushroom cultivation systems, the foregoing patents reflect the current state of the art of which the present inventors are aware. Reference to, and discussion of, these patents is intended to aid in discharging Applicants' acknowledged duty of candor in disclosing information that may be relevant to the examination of claims to the present invention. However, it is respectfully submitted that none of the above-indicated patents disclose, teach, suggest, show, or otherwise render obvious, either singly or when considered in combination, the invention described and claimed herein. The foregoing patents and the bottle-based method of mushroom cultivation generally described above typically employs sterilized bottles containing a pasteurized or sterilized nutrient media in which mushroom mycelium grows and produces fruiting bodies. The bottles typically have a porous, gas permeable cap, and an opening through which the fruiting bodies emerge while the mycelium develops in the nutrient media. Conventional prior art bottle caps for polypropylene bottles employed in the bottle system have filters that allow for proper gas exchange, but they generally do not prevent entry of small insects, mites and mold spores. The prior art designs generally employ a cylindrical foam filter enclosed in the bottle cap with multiple openings to allow for gas exchange for the growing mycelium. Ubiquitous fungus-loving mites are attracted to the mycelium and/or the substrate in the bottle and can easily penetrate the cap and the enclosed filter because of their small size (i.e., generally between lOOμm and 240μm). The mites often carry with them competitor spores, pathogenic mold spores, and/or bacteria, all of which contaminate the substrate and render it unusable by the mycelium. Contaminated units must then be removed from the cultivation house and are lost for the production cycle, resulting in wasted manpower hours, materials, energy consumption, and fresh mushroom product.

Furthermore, contaminated bottles present a serious threat to surrounding, uncontaminated units as they serve as a breeding ground for additional populations of mites and foster further mite invasion. Mite loss is the leading cause of crop loss in the bottle-based mushroom cultivation industry in Japan. Therefore, it would be desirable to provide a mycoculture bottle cap filter assembly that allows for suitable gas exchange during mycelium cultivation but prevents infestation of the inoculated bottle with damaging microscopic pests. It would further be desirable that the filter assembly be capable of sterilization in an autoclave so that the filter could be reused in multiple cultivation cycles. Finally, it would be desirable to have a mycoculture bottle cap filter assembly suitable for use in a bottle-based mushroom cultivation system that employed inexpensive filter materials.

Disclosure of Invention

The mycoculture bottle cap filter assembly of the present invention comprises a hollow-bodied bottle cap, preferably polypropylene, which includes a microporous filter and a gasket. The gasket includes surface features, preferably cylindrically-shaped vertically disposed nubs having a conical top, and it is shaped and sized for placement on the interior ledge of the bottle cap base. It is securely held in place by being interposed between the interior ledge and either the lower rim of the bottle cap cover or the undersurface of the bottle cap cover top. When the cap cover is in place, the surface features on the gasket and the undersurface of the bottle cap cover top cooperate to define air gaps that permit gas exchanges between the atmosphere, the interior space of the cap, and the bottle chamber, while simultaneously preventing pest infestation. The gas exchange between the bottle chamber and both the interior space of the cap and the outside atmosphere takes place through the microporous filter.

The bottle cap/bottle cap filter combination of the present invention provides protection against mite-vectored contamination in mushroom cultivation systems employing the bottle method, thus solving the problems of the prior art bottle filter systems. Instead of a foam disc, the bottle cap filter used in the present invention employs a microporous filter disc and a gasket that uses a pressure contact seal to hold the filter in place. Components of the present inventive system may be autoclaved and reused for several production cycles. Furthermore, the inventive gasket and microporous filter disc combination of the present invention is well suited for installation in many existing bottle caps in use. The bottle cap may be retrofitted to accept the inventive filter simply by removing the conventionally used foam disc and replacing it with the inventive filter. The bottle cap filter assembly of the present invention does not allow the passage of or penetration by anything larger than ~1.0 μm. Even the smallest mites cannot penetrate the filter media and are prevented from contaminating bottles. The inventive apparatus thus limits losses and curtails the opportunity for further breeding. It also protects developing units from mold spore contamination caused by normal airflow into the filter cap.

It is therefore an object of the present invention to provide a new and improved mycoculture bottle cap filter assembly which allows gas exchange between a mycoculture bottle interior and the outside atmosphere while preventing pest infestation of the mycelium. It is another object of the present invention to provide a new and improved mycoculture bottle cap filter assembly that is inexpensive and permits repeated use.

A further object or feature of the present invention is a new and improved mycoculture bottle cap filter assembly in which all of the assembly components can be sterilized in an autoclave for reuse.

An even further object of the present invention is to provide a novel mycoculture bottle cap filter assembly in which filtration is effected by a combination flexible, deformable gasket and a thin microporous fabric filter.

Other novel features which are characteristic of the invention, as to organization and method of operation, together with further objects and advantages thereof will be better understood from the following description considered in connection with the accompanying drawing, in which preferred embodiments of the invention are illustrated by way of example. It is to be expressly understood, however, that the drawing is for illustration and description only and is not intended as a definition of the limits of the invention. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming part of this disclosure. The invention resides not in any one of these features taken alone, but rather in the particular combination of all of its structures for the functions specified.

There has thus been broadly outlined the more important features of the invention in order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described hereinafter and which will form additional subject matter of the claims appended hereto. Those skilled in the art will appreciate that the conception upon which this disclosure is based readily may be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.

Further, the purpose of the Abstract is to enable the national patent offices, the public generally, and especially the scientists, engineers and practitioners in the art who are not familiar with patent or legal terms or phraseology, to determine quickly from a cursory inspection the nature and essence of the technical disclosure of the application. The Abstract is neither intended to define the invention of this application, which is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way. Certain terminology and derivations thereof may be used in the following description for convenience in reference only, and will not be limiting. For example, words such as "upward," "downward," "left," and "right" would refer to directions in the drawings to which reference is made unless otherwise stated. Similarly, words such as "inward" and "outward" would refer to directions toward and away from, respectively, the geometric center of a device or area and designated parts thereof. References in the singular tense include the plural, and vice versa, unless otherwise noted.

Brief Description of the Drawings

Referring now to the several view of the drawings of the mycoculture bottle cap filter assembly for use in bottle-based mushroom cultivation systems of the present invention:

FIG. 1 is an exploded side view in perspective of the inventive mycoculture bottle cap filter assembly, showing the filter as it will be interposed between the bottle cap base and the bottle cap cover; FIG. 2 A is a exploded side view in elevation of the apparatus of FIG. 1 showing detail of the filter gasket and bottle cap base configurations;

FIG. 2B is a cross-sectional side view in elevation of the apparatus of FIG. 2A;

FIG. 3 A is a top plan view of the filter assembly of the inventive apparatus; FIG. 3B is a cross-sectional exploded side view in elevation of the inventive filter, showing a slightly different configuration of surface structure to create a tight seal;

FIG. 4 is a top view of an alternative embodiment of the filter assembly of the present invention having cross members spanning the diameter of the filter gasket to provide added structural support for the microporous filter material; FIG. 5 is a cross-sectional side view in elevation of the filter of FIG. 4;

FIG. 6 is a bottom view of the filter of FIGS. 4 and 5; and

FIG. 7 is a perspective view of the preferred embodiment of the gasket of the filter assembly of the present invention.

Drawings Reference Numerals: 10 mycoculture bottle-cap filter assembly

12 filter gasket 12a upper surface of gasket 12b lower surface of gasket 14 microporous filter material 16 gasket rim

18 interior ledge of standard mushroom bottle cap base 20 bottle cap base 22 lower rim of bottle cap cover 24 bottle cap cover 26 undersurface of bottle cap cover top 28 bottle cap cover top 30 side wall of bottle cap cover 32 interior space in bottle cap 34 interior circumferential walls of cap cover side wall

36 wall of bottle cap base

37 neck of bottle cap base

38 air gaps 39 opening in neck of bottle cap base

40 partition rim

42 bottle interior

44 surface structure on upper surface of filter gasket

45 air passages 50 alternative filter gasket assembly

52 cross member

54 interior diameter of filter gasket

56 microporous filter material 56

58 surface structure 60 filter gasket

70 preferred embodiment of filter gasket

72 upper surface

74 lower surface

76 rim 78 cylindrical projections

Best Mode for Carrying Out the Invention

Referring to Figs. 1 through 7, wherein like reference numerals refer to like components in the various views, FIG. 1 is an exploded side view in perspective showing a first preferred embodiment of the improved mycoculture bottle cap filter assembly for use in mushroom cultivation systems of the present invention, while FIGS. 2 A and 2B are, respectively, an exploded side view in elevation and a cross-sectional side view in elevation of the apparatus of FIG. 1. FIG. 3 A is a top plan view of the filter assembly of the inventive apparatus, while FIG. 3B is a cross-sectional exploded side view in elevation of the inventive filter assembly, showing a slightly different configuration of surface structure to create a tight seal.

These views collectively show that the inventive apparatus 10 comprises a filter gasket 12 having an upper surface 12a and a lower surface 12b with microporous filter material 14 preferably welded to at least the lower surface 12b, and preferably the lower surface and the gasket rimlδ. Alternatively, the filter material can be separate and discrete. The filter gasket is adapted for interposition between the interior ledge 18 of a standard mushroom bottle cap base 20 and either the lower rim 22 of the bottle cap cover 24, or the undersurface 26 of the cover top 28. The filter gasket is preferably fabricated from a resilient material, such as natural rubber, synthetic rubber, or another elastomer, and preferably has a Shore A hardness of between 40 and 90.

As is well known, the bottle cap cover has a side wall 30 that snap fits within and against the circumferential interior walls 34 of the cap cover side wall to define an interior void or space 32 in the bottle cap. The bottle cap base 20 includes a wall 36 that tightly fits onto a standard polypropylene bottle neck (not shown) with a compression fit. The base of the cap base 20 includes a neck 37 having an opening 39 into the bottle interior when installed on the bottle.

When the cap cover is in place, the assembled cap includes air gaps 38 defined by the cap cover side wall 34 and an interior partition rim 40 which permit the exchange of gases between the atmosphere and the bottle interior 42, via the interior space 32 of the cap, the filter 14, and the opening 39 of the bottle cap base neck 37. (The bottle interior 42 is indicated positionally in FIG. 2B, but is not depicted structurally.)

Most essential to the present invention, a plurality of spaced-apart surface structures 44 vertically disposed on the upper surface 12a of the filter gasket cooperate with the undersurface 26 of the cover top 28 to define a plurality of air passages 45 that allow for the gas exchange from the bottle interior, through the microporous filter material 14, the air gap 38, and the atmosphere. While allowing such gas exchange, these structures also function as pressure seal contacts that ensure that the gasket rim 16 is in hermetic registration with the bottle cap base ledge 18. Preferably the surface structure comprises a plurality of generally cylindrically-shaped projections having conically- or hemispherically-shaped tips.

Accordingly, the filter assembly of the present invention provides for gas exchange between the mycoculture bottle interior and the outside atmosphere only through the microporous filter disk 14, thereby preventing infestation by pests larger than the pore size of the microporous filter material. At a minimum the material must be a substantially planar thin film which is gas permeable and capable of sterilization in an autoclave without withering. Preferably, the filter material is high density polyethylene (HDPE) fibers, randomnly distributed, flash spun, and bonded by heat and pressure without binders or sizers, such as filter material selected from the group consisting of DuPont TYVEK® 1042B, 1059B, and 1073B, and AGRIBON™ Ag-15, Ag-19, Ag-20, Ag-30, Ag-50, and Ag-70 . The material preferably has a Gurley Hill porosity of between 10 and 25 seconds for 100 cubic centimeters of air to pass through one square inch of material under a pressure of approximately 4.9 inches of water, and a moisture vapor transmission rate (as tested via the Lyssy method) of between 1600 and

1650 g/m²/day. Porosity and MVTR outside these ranges may still provide for gas exchange and pest resistance, though cultivation of the mycelium may not be as efficient. In fact, selection of filter material is driven by species-specific optimum conditions, particularly with respect to gas and vapor permeability. Other filter materials could be employed as long as they possessed sufficient gas permeability, and water-, particle-, chemical-, puncture-, tear-, and abrasion-resistance. When TYVEK® material is employed, its rough side may be welded to the lower surface 12b of filter gasket 12, if deemed necessary; however, as noted, the filter material may remain separate and discrete and may simply be captured underneath the lower surface of the filter gasket which is interposed between the bottle cap cover and the bottle cap base.

FIGS. 4, 5 and 6 are, respectively, top, side elevation, and bottom views of a second preferred embodiment 50 of the present invention having at least one cross member 52 spanning the interior diameter 54 of the filter gasket to provide structural support for the microporous filter material 56. Otherwise the structure and function of this embodiment is identical to that of the first preferred embodiment, including provision of surface structure 58 disposed on the upper surface of the gasket 60.

FIG. 7 shows details of the preferred embodiment of the filter gasket 70 employed in the present invention. As will be readily appreciated, the filter gasket comprises a ring of preferably deformable material having an upper surface 72, a lower surface 74, and a rim 76. A plurality of generally cylindrical, deformable projections 78 are disposed on the upper surface and terminate at their upper ends in a taper of some kind, preferably dome-shaped or conically- shaped. This taper allows the tip to deform outwardly when under compressive forces from the bottle cap cover.

It will be appreciated, then, that the present invention, in its most essential aspect, comprises a bottle cap base having an interior ledge and interior circumferential walls, and a neck with an opening; a bottle cap cover having a cover top, an undersurface, and a lower rim, in which the rim is adapted to fit within the interior circumferential walls of the bottle cap base in such a manner as to bring the lower rim of the cover into proximity with the interior ledge of the base. The base and the cover thereby define an interior space and at least one air passage between the interior space and the outside atmosphere. A filter gasket is interposed between the undersurface of the cover and the interior ledge of the base. The filter gasket has a rim, an upper surface and a lower surface, and includes a plurality of spaced-apart surface structures on the upper surface. The surface structures engage the undersurface of the cover to define a plurality of air passageways that permit gas exchange between the mushroom cultivation bottle interior and the outside atmosphere, via the interior space and the opening in said neck of said bottle cap base. Finally, a thin, planar microporous filter disk is interposed and captured between the lower surface of the filter gasket and the interior ledge of the base, such that gas exchange takes place only through the microporous filter.

The foregoing disclosure is sufficient to enable one having skill in the art to practice the invention without undue experimentation, and provides the best mode of practicing the invention presently contemplated by the inventor. While there is provided herein a full and complete disclosure of the preferred embodiments of this invention, it is not intended to limit the invention to the exact construction, dimensional relationships, and operation shown and described. Various modifications, alternative constructions, changes and equivalents will readily occur to those skilled in the art and may be employed, as suitable, without departing from the true spirit and scope of the invention. Such changes might involve alternative materials, components, structural arrangements, sizes, shapes, forms, functions, operational features or the like.

Accordingly, the proper scope of the present invention should be determined only by the broadest inteφretation of the appended claims so as to encompass all such modifications as well as all relationships equivalent to those illustrated in the drawings and described in the specification.

Claims

CLAIMS What is claimed as invention is:

1. A bottle cap filter assembly for attachment to a mycoculture bottle used in a bottle-based mushroom cultivation system, comprising: a bottle cap base having connection means for attaching said bottle cap base to the mycoculture bottle; a bottle cap cover attached to said bottle cap base and defining an interior space and at least one air passage between the interior space and the outside atmosphere; a filter gasket inteφosed between said bottle cap cover and said bottle cap base, said filter gasket having an upper surface with surface structure such that said filter gasket and said bottle cap cover define at least one air passageway that permits gas exchange between the outside atmosphere and the interior space defined by said bottle cap base and said bottle cap cover; and a gas-permeable, microporous filter adapted for inteφosition between said filter gasket and said bottle cap base, such that gas exchange between the mycoculture bottle interior and the outside atmosphere takes places only through said microporous filter.

2. The apparatus of claim 1, wherein said connection means is a compression fit wall.

3. The apparatus of claim 1, wherein said bottle cap base includes an interior ledge and an interior circumferential wall, said bottle cap cover has a cover top with an undersurface, and a sidewall with a lower rim, and wherein said filter gasket is inteφosed between said lower rim and said interior ledge.

4. The apparatus of claim 3, wherein said filter gasket has a lower surface, and wherein said microporous filter is inteφosed between said lower surface and said interior ledge of said bottle cap base.

5. The apparatus of claim 1 , wherein said microporous filter comprises high density polyelthylene (HDPE) fibers.

6. The apparatus of claim 6, wherein said HDPE fibers are randomnly distributed.

7. The apparatus of claim 1, wherein said microporous filter comprises material selected from the group consisting of DuPont TYVEK® 1042B, 1059B, and 1073B and AGRIBON™ Ag-15, Ag-19, Ag-20, Ag-30, Ag-50, and Ag-70.

8. The apparatus of claim 1, wherein said microporous filter comprises material should having a Gurley Hill porosity of between 10 and 25 seconds.

9. The apparatus of claim 1, wherein said microporous filter comprises material having a moisture vapor transmission rate of between 1600 and 1650 g/m²/day.

10. The apparatus of claim 1, wherein said microporous filter is welded to said filter gasket.

11. The apparatus of claim 1, wherein said filter gasket is fabricated from resilient material having a Shore A hardness of between 40 and 90.

12. A bottle cap filter assembly for use in bottle-based mushroom cultivation systems, comprising: a bottle cap base having an interior ledge and interior circumferential walls, and a neck with an opening, said bottle cap base adapted for connection to a bottle; a bottle cap cover having a cover top, an undersurface, and a lower rim, said rim adapted to fit within said circumferential walls of said bottle cap base so as to bring said lower rim into proximity with said interior ledge of said bottle cap base, said bottle cap base and bottle cap cover defining an interior space and at least one air passage between the interior space and the outside atmosphere; a filter gasket inteφosed and captured between said undersurface of said bottle cap cover and said interior ledge of said bottle cap base, said filter gasket having a rim, an upper surface and a lower surface, and including a plurality of spaced-apart surface structures on said upper surface, wherein said surface structures engage said undersurface of said bottle cap cover so as to define a plurality of air passageways that permit gas exchange between the mushroom cultivation bottle interior and the outside atmosphere, via the interior space and the opening in said neck of said bottle cap base; and a microporous filter adapted for inteφosition between said lower surface of said filter gasket and said interior ledge of said bottle cap base, such that gas exchange takes place only through said microporous filter.

13. The apparatus of claim 12, wherein said microporous filter is welded to said filter gasket rim.

14. The apparatus of claim 12, wherein said microporous filter comprises high density polyelthylene (HDPE) fibers.

15. The apparatus of claim 14, wherein said HDPE fibers are randomnly distributed.

16. The apparatus of claim 12, wherein said microporous filter comprises material selected from the group consisting of DuPont TYVEK® 1042B, 1059B, and 1073B.