In 1925, a French chemist named Maurice Lemoigne, working at the Pasteur Institute in Lille, was studying a common soil bacterium called Bacillus megaterium. Under the microscope, he noticed something odd: the cells contained small refractive granules. They weren’t the usual cellular machinery. They had a distinct shape, a faint sheen under polarized light, and they appeared and disappeared depending on what the bacteria had been fed.
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Lemoigne investigated. The granules turned out to be a polymer — a long, plastic-like molecule made of repeating subunits — that the bacteria were producing as an internal energy store. He named it polyhydroxybutyrate, or PHB. The bacteria, he found, would build up these PHB granules when they had plenty of carbon-rich food, and break them back down when food ran short. The polymer was, in effect, bacterial fat: an internal stockpile of energy the cell could draw on later.
Lemoigne published his findings. They got mild attention from the microbiology community. Then they sat largely ignored for the next fifty years, while the world built an entire civilization on petroleum-based plastics that have nothing in common with the microbe-derived polymer Lemoigne had described.
The story of how that 1925 discovery eventually became the basis of PHA bioplastic — and why a polymer originally made and consumed by bacteria for their own metabolism turns out to be one of the cleaner answers to plastic pollution — is one of the more interesting threads in the history of biodegradable materials. It also offers a useful answer to a question that comes up often in compostable packaging: why does PHA actually biodegrade in marine and soil environments when so many other “biodegradable” claims fall apart? The short version is that nature already knows how to disassemble it.
What Lemoigne Actually Saw
Worth being precise about the original observation. Lemoigne wasn’t looking for plastic. The category “plastic” as we know it didn’t really exist yet — Bakelite had been invented in 1907 but the petroleum-plastic explosion was still decades away. Lemoigne was a microbiologist studying bacterial physiology, specifically how microbes store and use energy.
The granules he saw in Bacillus megaterium and other bacteria were physically distinct from the rest of the cell’s contents. They had a refractive index different from the surrounding cytoplasm. They could be stained with specific dyes that revealed their shape and concentration. The bacteria’s behavior around the granules was characteristic — they grew when carbon was abundant, shrank when food was scarce, disappeared entirely under starvation conditions.
Lemoigne extracted and characterized the polymer through the chemistry methods of his day. He determined that it was a polyester — chains of hydroxybutyrate units linked end-to-end. The molecular weight was high. The polymer was insoluble in water but degraded in dilute acid or under microbial enzymatic action.
The scientific significance, in 1925, was that bacteria had been shown to produce a high-molecular-weight polymer for energy storage. This was a notable observation in microbiology but didn’t connect to any obvious application. The world wasn’t yet paying attention to plastic alternatives because the world wasn’t yet drowning in plastic.
The discovery sat in the literature, cited occasionally in microbiology textbooks, otherwise dormant.
The Long Pause
For fifty years, PHB (and the broader family of polyhydroxyalkanoates that subsequent research showed bacteria produce) remained an academic curiosity. The petroleum-plastic industry took off after World War II. Polyethylene, polypropylene, polystyrene, PVC, and PET dominated packaging, durable goods, and almost every aspect of consumer products. The bacterial polyester Lemoigne had described didn’t have an obvious market angle.
A few research groups continued work on the bacterial side. Soviet researchers in the 1960s explored PHB as a potential surgical implant material because of its biodegradability inside the body. Some pharmaceutical applications got explored. A small academic literature accumulated.
The category waited.
The 1980s Industrial Awakening
In the late 1970s and early 1980s, two things changed.
First, the environmental awareness of plastic pollution started to crystallize as a public issue. Beach surveys documented persistent plastic debris. Marine biologists began identifying microplastic accumulation. The political and consumer landscape shifted.
Second, Imperial Chemical Industries (ICI) in the UK saw the commercial opportunity. ICI had access to advanced fermentation technology, industrial microbiology talent, and the engineering capability to scale microbial polymer production. The company developed a process using Alcaligenes eutrophus (now reclassified as Cupriavidus necator) to produce PHB and a related copolymer called PHBV — polyhydroxybutyrate-co-valerate. The ICI product was branded Biopol.
Biopol entered the market in the late 1980s as one of the first commercially-available bioplastics. It was used in some specialty applications: shampoo bottles for the eco-conscious brand Wella, biodegradable agricultural films, surgical sutures. The pricing was high — around 20 times the cost of conventional polyethylene per pound — which limited mass-market adoption.
The Biopol story moved through corporate hands several times. ICI spun off the Biopol division. Monsanto acquired it in 1996, hoping to integrate bioplastic into its broader agricultural-biotechnology portfolio. Monsanto sold to Metabolix in 1998. Metabolix partnered with ADM in the late 2000s for commercial scale-up of PHA under the brand Mirel. Production ramped up, then exited the market in 2012 when commercial economics didn’t work at the time.
The technology stayed in the literature and the patent landscape. The commercial momentum had to wait for the next wave.
The Modern Re-Emergence
The 2010s and especially the 2020s have seen PHA come back commercially in a more durable way. Several factors converged:
- Regulatory pressure: state and national bans on single-use plastics created demand for alternatives that biodegrade reliably in marine and soil environments.
- Improved fermentation economics: advances in industrial microbiology, feedstock options, and process control reduced PHA production costs.
- Investor interest: bioplastics attracted substantial venture capital starting around 2018.
- Brand demand: major consumer brands (PepsiCo, Bacardi, others) committed to compostable packaging targets that PHA could meet.
Current major producers include:
- Danimer Scientific (formerly MHG): largest US PHA manufacturer, focused on flexible packaging and straws.
- RWDC Industries (Singapore/US): targeting straws, food packaging, and personal care.
- Newlight Technologies (US): produces AirCarbon, a PHA-family material made from greenhouse gas methane as feedstock.
- CJ CheilJedang (South Korea): industrial-scale PHA fermentation.
- Several Chinese producers: emerging at substantial scale.
The category is still smaller than PLA (the dominant compostable plastic by volume) but growing faster as the marine-biodegradability advantage becomes more important to buyers.
Why the Bacterial Origin Matters
This is where the discovery story connects to why PHA actually biodegrades.
The reason PHA breaks down in marine, soil, and home compost environments — when most other “biodegradable” plastics struggle outside industrial composting facilities — is that the polymer is something nature has been making for billions of years and that other organisms have evolved to recognize and consume.
When bacteria make PHA inside their cells, they use specific enzymes called PHA synthases to polymerize the building-block monomers. When they need to reclaim the stored energy, they use other enzymes (PHA depolymerases) to break the polymer back into monomers, which feed back into normal metabolism.
Both classes of enzymes are widespread in nature. PHA depolymerases — the enzymes that break PHA down — exist in many soil bacteria, marine microbes, and other environmental organisms. When PHA enters a marine environment, soil, or compost pile, microbes already carrying PHA depolymerase genes recognize the polymer as food and start breaking it down.
This is fundamentally different from the situation with petroleum-based plastics. Polyethylene, polypropylene, and polystyrene are molecular structures that didn’t exist on Earth before the 20th century. Microbes haven’t had time to evolve enzymes that target these polymers. The polymers persist because no organism’s metabolism is tuned to disassemble them.
PHA’s biodegradability is essentially a free lunch — the polymer is a natural material, the disassembly machinery already exists in nature, and the breakdown happens whenever PHA encounters an appropriate microbial community. Marine environments work. Soil works. Backyard compost works (more slowly than industrial). Even ocean sediment works given enough time.
This is the working answer to “why does PHA actually biodegrade?” The bacteria that make it have, for billions of years, also been the bacteria that consume it. Other organisms have learned to consume it too. When the material enters the environment, the disposal infrastructure — biological, microbial — is already in place.
What Bacteria Make PHA
The PHA-producing bacterial family is wide. Some of the more notable species:
- Cupriavidus necator (formerly Alcaligenes eutrophus, Wautersia eutropha): the workhorse of commercial PHA production. Hardy, scalable, well-characterized.
- Pseudomonas species: produce a variety of PHAs with different properties.
- Bacillus species: including the Bacillus megaterium that Lemoigne first studied.
- Halomonas species: salt-loving bacteria that can grow in seawater, attractive for industrial production because they don’t require freshwater fermentation.
- Methanotrophs (methane-eating bacteria): including Methylocystis species that Newlight Technologies uses to convert methane to PHA, capturing greenhouse gas as feedstock.
- Cyanobacteria: photosynthetic microbes that can produce PHA directly from sunlight and CO2 in some experimental setups.
The diversity matters because different species produce slightly different PHA chemistries — different monomer ratios, different molecular weights, different physical properties. The PHB Lemoigne discovered is one specific PHA. PHBV is a related copolymer with valerate units mixed in. PHBHHx incorporates hexanoate. Each variation has slightly different mechanical properties, melting temperatures, and biodegradation rates.
For the consumer-product applications most people encounter, PHBV-style copolymers are common — they balance flexibility and crystallinity better than pure PHB.
Why the Discovery Took So Long to Matter
Worth thinking about why the gap between Lemoigne’s 1925 observation and meaningful commercial PHA was so long. A few factors:
The plastic problem didn’t exist yet. In 1925, the world’s plastic problem was zero. There was no demand for biodegradable alternatives because there was nothing to replace.
Petroleum plastic was cheap. Once the oil industry scaled up after WWII, petroleum plastics were so cheap that any alternative had to compete on commodity pricing. Bacterial fermentation can’t easily match the cost of cracking ethylene from oil.
Fermentation technology was primitive. Industrial microbial fermentation in 1925 was at brewery and dairy scale. Producing PHA at packaging volume required modern bioreactor technology and process control that didn’t exist until much later.
The biology required understanding. Lemoigne characterized the polymer chemistry, but the genetics, biochemistry, and metabolic engineering needed to optimize PHA production took decades to develop. Cloning the PHA synthase genes happened in the 1980s. Strain engineering to overproduce PHA happened in the 1990s and 2000s.
The political economy wasn’t ready. Government regulations restricting plastic use, consumer demand for biodegradable alternatives, and corporate sustainability commitments all developed in the 21st century. The market signal that would justify PHA’s higher production cost wasn’t there until recently.
The 100-year gap between discovery and meaningful commercialization isn’t unusual for fundamental biology research. It just looks long when viewed retrospectively against the urgency of the current plastic problem.
The Practical Implication for Buyers Today
For B2B operators and compostable foodware buyers, the bacterial-origin story explains why PHA-based products are increasingly the premium pick when home-compost or marine biodegradability matters:
Marine biodegradability: PHA breaks down in ocean conditions. PLA generally doesn’t (PLA needs industrial composting temperatures). For products likely to end up in marine environments — straws, takeaway containers, packaging — PHA has a real environmental advantage.
Home compostability: PHA carries home-compostable certification more readily than PLA. For consumer-facing products where end-of-life depends on backyard composting, PHA is the more reliable choice.
Industrial compostability: PHA breaks down in industrial composting facilities, with somewhat more reliable timelines than PLA across varying facility conditions.
The trade-off: PHA costs meaningfully more than PLA at current production scale. The gap is closing as production capacity expands but hasn’t disappeared.
For commercial operators sourcing across compostable categories — compostable cups and straws, compostable food containers, PHA straws — PHA-specific products often appear in premium tiers within the broader compostable line. The cost premium reflects the production economics; the environmental case justifies it for buyers who prioritize marine and home-compost end-of-life.
What’s Coming Next
PHA’s commercial trajectory is on a steady upward curve. A few developments worth watching:
Lower-cost feedstock: methane-to-PHA processes (Newlight) and waste-stream-to-PHA processes (using food industry residues) are reducing input costs.
Higher-performance variants: incorporating different monomers produces PHA copolymers with mechanical properties closer to conventional plastic, expanding the application range.
Production scale-up: announced commercial-scale plants in the US, China, and Korea will substantially increase global PHA capacity in the next 5 years.
Regulatory tailwinds: marine biodegradability requirements in some markets favor PHA over alternatives that don’t biodegrade in oceans.
New applications: medical (sutures, tissue scaffolds), agricultural (biodegradable mulch films), and consumer goods (packaging, single-use products) all expanding.
The long gap from Lemoigne’s discovery to commercial scale is finally closing. The category is on track to be a meaningful slice of the plastic market within the next decade.
The Quiet Loop
The PHA story is, ultimately, about a closed loop that already existed in nature. Bacteria make polyester to store energy. Other bacteria break it down to recover the energy. The cycle has been running in soil, ocean, and freshwater microbial communities for billions of years.
Human industry observed the bacteria, learned to grow them at scale, harvested the polymer, and used it to make consumer products. When those products end up in soil, ocean, or compost, the same bacterial communities that have always processed the polymer continue to do so. The polymer goes back into the cycle.
It’s the kind of solution that works because it doesn’t require building new infrastructure. The disposal system was already there. The challenge was finding a polymer that fit it. Lemoigne found that polymer in 1925. The world took a hundred years to recognize what to do with it.
For someone holding a PHA straw at a coffee shop today, the connection back to a French microbiologist watching bacterial granules under a microscope a century ago is invisible. The straw works. It biodegrades. The bacteria that make and consume PHA continue their business in soil and water everywhere, oblivious to the industry that learned from them.
That’s the discovery story. The bacteria did the original engineering. The rest of us are just catching up.
Verifying claims at the SKU level: ask suppliers for a current Biodegradable Products Institute (BPI) certificate or an OK Compost mark from TÜV Austria, and check that retail-facing copy meets the FTC Green Guides qualifier requirement on environmental claims.