Clean Room Basics

Part of Antibiotics

How to create and maintain a sufficiently contamination-free environment for antibiotic production without modern cleanroom technology.

Why This Matters

Penicillin production fails most often not because of poor mold cultivation or extraction chemistry, but because of contamination. A single airborne spore from a competing mold or bacterium landing in your growth medium can ruin an entire batch — or worse, produce a toxic byproduct that is administered to a patient.

A pharmaceutical cleanroom uses HEPA filters, positive pressure air systems, and UV sterilization. A rebuilding community has none of these. However, the underlying principle is achievable with low technology: reduce the concentration of airborne contaminants in the working space, sterilize all surfaces and equipment, and handle materials in ways that minimize contamination pathways.

The standard does not need to be pharmaceutical-grade. It needs to be good enough that your penicillin cultures reliably contain Penicillium and not competitor organisms. This is achievable with discipline and simple materials.

Choosing and Preparing the Space

Room Selection Criteria

The ideal production room has:

• Minimal foot traffic — fewer people moving through means fewer airborne particles
• No exposed soil or plant material — these are major mold spore sources
• Hard, cleanable surfaces — stone, plaster, tile, sealed wood; avoid bare earth floors and rough timber
• Controllable air flow — windows that open and close, not open eaves
• Away from kitchens and composting areas — these are high-spore environments

A small inner room (3–4 m²) is preferable to a large space. Smaller volume means fewer total contaminants.

Initial Deep Clean

Before any antibiotic work begins:

1. Remove all organic clutter — old wood, stored grain, fabric, dried plants
2. Scrub all surfaces with hot water and ash lye (or vinegar) — walls, floor, ceiling if reachable
3. Allow to dry completely — moisture supports mold growth on surfaces
4. Whitewash walls with lime wash (calcium hydroxide in water) — lime is strongly alkaline and inhibits surface mold
5. Seal cracks in walls and floor with clay, plaster, or cement to eliminate hiding spots for dust and spores

Ongoing Maintenance

• Sweep with a damp cloth or mop, not a dry broom (dry sweeping aerosolizes particles)
• Wipe work surfaces with dilute vinegar (1:5 with water) before each session
• Limit entry to essential personnel only
• Anyone entering should have clean hands and not recently handled soil, animal feed, or compost

Air Management

The Problem with Air

Normal outdoor air contains hundreds to thousands of mold spores per cubic meter. Indoor air in agricultural settings can be far higher. Your Penicillium cultures will be outcompeted if exposed to this air freely.

Settling Time Principle

When you disturb air — opening doors, sweeping, people moving — spore concentration spikes. Allow 15–30 minutes of stillness for particles to settle before opening culture vessels. This single practice dramatically reduces contamination rates.

Protocol:

1. Enter the room
2. Perform any necessary movement (carrying equipment)
3. Close the door and wait 20 minutes without moving around
4. Only then open culture flasks or plates

Improvised Air Filtration

A simple air pre-filter can be made by hanging multiple layers of tightly woven cloth across doorways and window openings:

• Use wool felt or tightly woven linen, 4–6 layers thick
• Dampen slightly with water before work sessions — moist fibers capture particles better
• Change or wash cloths every few days

This will not achieve pharmaceutical standards but meaningfully reduces incoming spore load.

Positive Pressure (Advanced)

If a bellows or fan is available, maintaining slightly higher air pressure inside the work room than outside prevents air from flowing inward through gaps. Any leaks will flow outward, pushing contaminants away. Even a gentle manual bellows pumping filtered air in achieves some positive pressure benefit.

Surface Sterilization Methods

Heat

The simplest and most reliable method for equipment sterilization:

Item	Method	Duration
Glass flasks	Dry heat oven (160°C)	60 minutes
Metal tools	Flame or boiling water	10 minutes boiling
Cloth covers	Steam or boiling	15 minutes
Work surface	Flaming with alcohol	Brief pass

Without a thermometer, calibrate dry heat oven by observing: paper should not brown at the correct temperature (160°C). If paper browns, temperature is too high.

Chemical Sterilization

When heat is not practical:

• 70% alcohol (ethanol or isopropanol): most effective concentration for surface wipe-down. Pure alcohol evaporates too fast to kill spores; 70% retains contact time. Achievable from fermentation distillate diluted appropriately.
• Bleach solution (1 tablespoon per liter water): effective but corrosive to metals and leaves residue that can inhibit Penicillium growth — rinse thoroughly after use
• Vinegar (5%): weaker but safe and available — use for general surface wipe, not sterilization of culture equipment

UV Light (If Available)

Sunlight contains UV radiation that kills surface microorganisms. Lay sterilized but contamination-prone items in direct sunlight for 30–60 minutes as a supplementary step. This is not a substitute for heat or chemical sterilization but provides additional kill on surfaces.

Personal Hygiene Protocols

Hands

Hands are the primary contamination vector in any manual production process:

1. Wash hands with soap and water for 30 seconds before entering production area
2. Rinse with dilute alcohol or vinegar after washing
3. Do not touch face, hair, or clothing once working
4. If hands contact a non-sterile surface accidentally, re-wash before continuing

Clothing

• Wear dedicated clothing kept in the production room — do not wear outdoor clothing that has been in barns, gardens, or kitchens
• Hair should be covered or tied back
• Avoid loose clothing that sheds fibers

Illness and Exclusion

Anyone with respiratory illness (coughing, sneezing) must not enter the production room. Respiratory droplets carry enormous microbial loads. A single sneezing event in an open culture room can contaminate every vessel.

Practical Cleanliness Hierarchy

Not all production steps require the same level of cleanliness:

Highest cleanliness required:

• Opening culture flasks to add medium or transfer mold
• Preparing final penicillin extract for patient use
• Filtration step

Moderate cleanliness:

• Preparing growth medium (before sterilization)
• Incubation room maintenance

Standard hygiene only:

• Autoclave/sterilization of glassware
• Preparing substrate ingredients

Concentrate your strictest practices around the moments when sterile materials are exposed to the environment. Obsessing over cleanliness at every step leads to burnout; applying discipline at the critical moments achieves the necessary result.