How do pangolins digest insects with hard exoskeletons?

Pangolins break down chitin, the tough polymer in insect exoskeletons, through a two-tier system. The host produces its own acidic chitinase enzyme called CHIA5, which is expressed across all major digestive organs. Simultaneously, specialised gut bacteria from families including Lachnospiraceae and Ruminococcaceae carry GH18 chitinase genes that further degrade chitin into usable nutrients. A 2023 study in mSystems found that 132 of 314 reconstructed bacterial genomes from myrmecophagous mammals carried active chitinolytic genes.

What bacteria dominate the pangolin gut?

In healthy pangolins, the phylum Firmicutes dominates at 62 to 74 percent of the bacterial community, followed by Proteobacteria at 13 to 18 percent. The genus Clostridium sensu stricto 1 is typically the most abundant, comprising about 28 to 30 percent of gut bacteria. A 2021 PeerJ study identified 271 distinct bacterial genera across 14 phyla in Sunda pangolins. When Proteobacteria rises above 50 percent, particularly Escherichia and Shigella, it is a reliable indicator of captivity-related stress and dysbiosis.

Does captivity change the pangolin gut microbiome?

Yes, significantly. A 2024 comparative study in Animals found that Malayan pangolins kept in captivity for five years had Proteobacteria levels of 53 percent, compared to 13 percent in Chinese pangolins held for only two years. Longer captivity correlated with elevated Escherichia coli, Shigella, and Salmonella, alongside reduced microbial diversity. Captive pangolins also show elevated serum cortisol, with mean levels of 643 nanograms per decilitre, and the stress hormone negatively correlates with beneficial bacterial populations.

Do all ant-eating mammals share similar gut bacteria?

Remarkably, yes. A landmark 2014 study in Molecular Ecology examined 15 myrmecophagous species across five mammalian orders, including pangolins, anteaters, aardvarks, armadillos, and aardwolves. Despite having diverged more than 100 million years ago, these species showed convergent gut microbiome composition. The aardwolf, which split from carnivorous hyenas within the last 10 million years, had shifted its entire gut bacterial community toward the myrmecophage pattern. Diet, not evolutionary ancestry, drives the structure of the gut microbiome in these species.

Has the gut microbiome of South Africa's Temminck's ground pangolin been studied?

No dedicated gut microbiome study has been published specifically on Temminck's ground pangolin. The only data comes from a 2023 mSystems study by Teullet and Delsuc that included Smutsia temminckii as one of nine myrmecophagous species in a comparative chitin-digestion analysis. This represents a significant research gap given that South Africa handles dozens of confiscated pangolins annually through rehabilitation programmes. Understanding the wild microbiome baseline for this species would directly improve captive diet formulation and release outcomes.

Science & Research 27 May 2026 9 min read

Pangolin Gut Microbiome: The Hidden Bacteria That Make an Impossible Diet Work

Pangolins eat nothing but ants and termites. No fruit. No seeds. No carrion. Just insects encased in chitin, a structural polymer so tough it forms the exoskeletons of arthropods and the cell walls of fungi. Mammals do not produce the enzymes to break chitin down efficiently on their own. Yet pangolins thrive on this diet across four continents, extracting enough nutrition from armoured insects to sustain body masses of up to 33 kilograms. The answer to how they manage this lies not in the pangolin itself, but in the hundreds of bacterial species living inside its gut.

Over the past decade, a series of microbiome studies has revealed that pangolins harbour a specialised intestinal bacterial community unlike that of any other mammalian group. These bacteria carry genes for chitin degradation, produce enzymes that complement the pangolin's own limited chitinase toolkit, and form a co-evolved partnership that has been refined over tens of millions of years. Understanding this partnership is no longer just an academic curiosity. It has become central to keeping confiscated pangolins alive in rehabilitation centres, where gut dysbiosis is a leading cause of death.

What Lives Inside a Pangolin

The first comprehensive gut microbiome survey of any pangolin species was published in PeerJ in 2021 by Fuhua Zhang and colleagues at South China Normal University. Working with nine captive Sunda pangolins, the team generated over 700,000 clean sequencing reads and identified bacteria spanning 14 phyla, 24 classes, 48 orders, 97 families, and 271 genera. The dominant phylum was Firmicutes at 73.7 percent of the community, followed by Proteobacteria at 18.4 percent, Actinobacteria at 3.4 percent, and Bacteroidetes at just 0.5 percent.

At the genus level, Clostridium sensu stricto 1 dominated at 29.4 percent, followed by Escherichia-Shigella at 13.6 percent and Terrisporobacter at 10.4 percent. The team also identified known chitin-degrading bacteria including Lactococcus, Bacteroides, Bacillus, and Enterococcus faecalis, all of which carry genes encoding chitinase enzymes from the GH18 glycoside hydrolase family.

A 2024 comparative study in Animals by Zhidong Dai and colleagues at Zhejiang Normal University expanded this picture by examining both Chinese and Malayan pangolins. Chinese pangolins showed Firmicutes dominance at 62 percent, while Malayan pangolins held in captivity for five years had Proteobacteria at 53 percent, with Escherichia alone at 45 percent. The team identified 45 distinct metabolic pathways associated with specialised nutrient extraction from a low-diversity insect diet.

The Chitin Problem

Chitin is the second most abundant biopolymer on Earth after cellulose. It provides structural rigidity to insect exoskeletons, forming dense crystalline sheets held together by hydrogen bonds. Breaking it down requires chitinase enzymes that cleave the beta-1,4-glycosidic linkages between N-acetylglucosamine units. Most mammals produce little to no chitinase. Pangolins are an exception, but only partially.

A 2025 study in Genome Biology and Evolution by Allio and Delsuc at the University of Montpellier revealed that pangolins possess a single functional acidic chitinase gene, CHIA5, expressed across all major digestive organs. Southern tamanduas carry four CHIA paralogs. Same dietary adaptation, entirely different genetic routes.

But one gene is not enough. The 2023 mSystems study by Teullet and Delsuc sequenced nine myrmecophagous species, including Temminck's ground pangolin. From 29 faecal samples they reconstructed 314 bacterial genome bins, of which 132 carried GH18 chitinase genes with 237 active chitinolytic sites. The primary chitinolytic families were Lachnospiraceae, Acutalibacteraceae, and Ruminococcaceae.

The pangolin runs a two-tier system. Its CHIA5 enzyme handles initial acidic breakdown in the stomach. Gut bacteria process partially degraded chitin further downstream. Neither tier works efficiently without the other.

Convergence Across Continents

Pangolins, anteaters, aardvarks, armadillos, and aardwolves are not closely related. They occupy five separate mammalian orders that diverged more than 100 million years ago. Yet a landmark 2014 study in Molecular Ecology by Delsuc, Metcalf, and colleagues demonstrated that these species share strikingly similar gut microbiome compositions. Using 16S rRNA gene sequencing across 15 myrmecophagous species, the team showed that ant-eating mammals cluster together in microbiome space regardless of phylogenetic position.

The most dramatic example was the aardwolf. A hyena-family member that switched from carnivory to termite-eating within the last 10 million years, it had completely restructured its gut bacterial community to resemble pangolins and anteaters rather than its carnivorous relatives. Diet, not ancestry, dictates the gut microbiome. The 2023 Teullet and Delsuc study deepened this by showing convergence extends to function: different bacterial species in different hosts independently carry chitinase genes. Of 314 bacterial genome bins, 194 were shared across host species while 115 were host-specific. Different bacteria, same job.

What Captivity Does to the Gut

Nearly every published pangolin microbiome study has relied on captive animals, and nearly every study reports the same pattern: captivity destroys the gut microbiome. The Dai et al. 2024 study quantified this clearly. Chinese pangolins held for two to two-and-a-half years maintained reasonable Firmicutes dominance and microbial diversity. Malayan pangolins held for five years showed Proteobacteria overgrowth to 53 percent, with pathogenic Escherichia coli, Shigella, and Salmonella at elevated levels. Shannon diversity index and Simpson index were both significantly lower in the long-captivity group.

A 2022 study by Jiao and Chen at the Guangdong Academy of Sciences connected dysbiosis to physiological stress. Captive pangolins showed serum cortisol averaging 643 nanograms per decilitre, with adult Sunda pangolins reaching 850. Cortisol negatively correlated with monocyte count and albumin, both immune markers. A 2025 Frontiers in Microbiology metabolome study by Xiang and colleagues added another layer: different pangolin species show distinct metabolomic profiles linked to their gut bacteria. There is no one-size-fits-all captive diet. Species-specific microbiome management is necessary.

Fixing the Captive Gut

A 2022 preprint from Guangdong Academy of Forestry explored supplementing captive diets with termitarium soil, the earth from termite mounds that wild pangolins ingest naturally. Adding 18 grams of unsterilised soil reduced inflammation-associated bacteria like Bacteroides while increasing beneficial short-chain fatty acid producers. A 2025 Research in Veterinary Science study tested probiotics on 12 Chinese pangolins with diarrhoea and found that five days of treatment significantly increased microbial diversity.

Perhaps most intriguing: a 2026 BMC Microbiology study on rescued Formosan pangolins isolated 10 lactic acid bacteria strains with less than 97.3 percent similarity to any known species in GenBank. These likely represent novel, undescribed Lactobacillus and Limosilactobacillus species. Pangolin guts may harbour bacterial lineages found nowhere else on Earth.

The South African Knowledge Gap

Temminck's ground pangolin is South Africa's only pangolin species and the focus of the country's rehabilitation and anti-trafficking efforts. The African Pangolin Working Group, co-founded by Prof Ray Jansen of Tshwane University of Technology, coordinates confiscation response, veterinary care, and release across multiple provinces. Dozens of pangolins pass through South African rehabilitation centres each year.

Yet no dedicated gut microbiome study exists for this species. The only published data comes from the 2023 Teullet and Delsuc mSystems study, where Temminck's ground pangolin was one of nine species in a comparative analysis. We know it carries chitinolytic bacteria. We know its microbiome converges with other myrmecophages. But we do not have a species-specific baseline that would allow South African rehabilitation programmes to design microbiome-informed diets and probiotic protocols.

This gap matters practically. Temminck's ground pangolins eat only four ant species and one termite species in the wild, as documented by Pietersen in a 2016 Journal of Zoology study. That extreme dietary selectivity, representing just 7.5 percent of available ant species in their habitat, almost certainly shapes a highly specialised gut microbiome adapted to processing those specific prey items. Captive diets built around commercially available ant species or artificial substitutes may support a fundamentally different bacterial community, one that lacks the precise enzymatic toolkit the animal evolved to depend on.

Studying wild Temminck's pangolin microbiomes is logistically formidable. The animals are solitary, nocturnal, lack eye-shine for spotlight detection, and rotate burrows every two to three nights. Faecal samples must be collected within minutes of defecation before microbial communities shift. The 2024 Dai study describes researchers entering enclosures every 30 minutes between 20:00 and 05:00 for immediate flash-freezing in liquid nitrogen. Replicating this in the Kalahari or Limpopo bushveld would require funding and institutional partnerships that do not yet exist.

Why the Microbiome Matters for Survival

The gut microbiome is not a peripheral detail of pangolin biology. It is the engine that makes an otherwise impossible diet viable. Without the right bacteria, a pangolin cannot extract sufficient nutrition from chitin-armoured insects. Every pangolin that dies in rehabilitation from gastrointestinal disease is a reminder that we are managing a host without understanding the microbial community it depends on.

For South Africa's Temminck's ground pangolin, the foundational work has not been done. Until someone sequences the gut bacteria of wild ground pangolins across multiple seasons and habitats, every captive diet protocol is an educated guess. The bacteria inside a pangolin are as worthy of conservation as the animal itself: an irreplaceable component of a system refined over 80 million years of co-evolution that will be lost entirely if pangolins disappear. Saving the pangolin means saving its microbiome.