Live Clostridium butyricum Preparation Veterinary Grade API for Tablets / Injections / Capsules / Powders / Granules / Premix / Solutions

Live Clostridium butyricum preparation veterinary grade API is a spore-enriched dried fermentation concentrate supplied for downstream manufacture of tablets, injections, capsules, powders, granules, premix, and solutions. Model CBV-API-10 is standardised to a nominal viable spore count of 1.0 × 10¹⁰ CFU/g; model CBV-API-50 is standardised to 5.0 × 10¹⁰ CFU/g. The dried material is produced by anaerobic fermentation, spore concentration, and lyophilization or low-temperature spray drying with a maltodextrin or calcium carbonate carrier. Both models are identical in strain and spore morphology and differ only in final standardised count and the mass of carrier required. Identification of the production strain is confirmed by 16S rRNA gene sequencing and ribotyping; the master cell bank is maintained under liquid nitrogen and tested for absence of Clostridium botulinum neurotoxin genes by polymerase chain reaction. Release for veterinary use requires absence of Salmonella in 25 g, moisture below 7.0%, and heavy metal limits given in the specification table. The product is not sold as a direct retail drug premix; it is supplied to licensed veterinary pharmaceutical manufacturers and feed additive formulators with a complete master file.

Fed-batch anaerobic fermentation is controlled at 37 ± 1 °C and pH 6.0–7.0; spore formation is induced by carbohydrate limitation and divalent metal ion adjustment in the final growth phase. The harvested broth is concentrated by continuous centrifugation, and the spore concentrate is microencapsulated with maltodextrin or calcium carbonate before drying. The resulting powder has a tapped density of 0.45–0.65 g/cm³ and an angle of repose below 35°. Standard bulk packaging is 1 kg or 5 kg aluminium-laminated foil pouches flushed with nitrogen to residual oxygen below 1.0%; 10 kg drums are available for premix manufacturers. Sporulation efficiency below 90% leads to batch rejection because it increases thermal tolerance variation; representative batch records show a coefficient of variation of spore count within 0.15 log across 10 consecutive production batches when the sporulation step is maintained at 35–37 °C for 18–24 h.

What Limits Recovery in Anaerobic Plate Enumeration for a Spore-Forming Veterinary API?

Plate enumeration for batch release is performed on reinforced clostridial medium after heat shock at 80 ± 1 °C for 10 min to select spores, followed by anaerobic incubation at 37 ± 1 °C for 48 ± 2 h. Recovery is sensitive to residual oxygen in the anaerobic jar; observed counts can be 0.2–0.5 log lower than the theoretical spore count if the anaerobic gas mixture contains oxygen above 0.5%. The certificate of analysis therefore reports the heat-shocked spore count and the total viable count, and release limits are set as lower acceptance thresholds. Moisture is controlled below 7.0% because residual water above 9.0% has been associated with progressive loss of heat-shock-resistant spores during storage in aluminium-laminated foil pouches at 25 °C / 60% RH. Non-spore contaminants are limited to 1.0 × 10³ CFU/g total aerobic bacteria and 1.0 × 10² CFU/g moulds and yeasts in the representative specification.

For tablet and capsule manufacture, the API is dry-blended with anhydrous lactose or microcrystalline cellulose before compression. Direct compression of a 500 mg tablet containing 1.0 × 10⁸ CFU per unit is feasible when 90% of the API particles pass through a 180 µm sieve and lubrication time with magnesium stearate is limited to 3–5 min. Longer lubrication on rotary tablet presses has been observed to reduce spore recovery by 0.1–0.3 log because of hydrophobic coating of spores. Injectable preparations are not produced by terminal sterilization of the raw API. The API is incorporated only into aseptic processing lines, and if a spore suspension is passed through a 0.22 µm sterilizing-grade membrane, aggregate retention may cause a variable count reduction; pre-filtration count is therefore verified at 1.5 times the target concentration. Oral solutions for drench or drinking water are prepared immediately before administration and held at 2–8 °C for no more than 12 h in sealed high-barrier containers to limit oxygen exposure and spore germination. Published data for injectable administration of live Clostridium butyricum spores in target species are limited; injectable development is treated as an investigational formulation, not a standard oral or feed dosage form.

Granules for oral suspension are produced by fluid-bed coating of sugar spheres with a spore suspension and a protective polymer layer; inlet air temperature is maintained at 35–40 °C, and product temperature is kept below 35 °C to avoid germination. Coating efficiency is assessed by spore count and moisture; failure to dry granules below 6.0% water can cause caking in high-humidity zones. Injectable spore suspensions are prepared in saline or dilute acetate buffer at pH 5.5–6.5; phosphate buffers that promote germination are avoided. No terminal moist-heat cycle is used because exposure to 121 °C for 15 min destroys viable cells and spores.

Microbiological Release Thresholds and Heavy Metal Limits for Dossier Compliance

Representative release limits are shown below. Final limits are dossier-specific and are established under the applicable veterinary medicinal product regulation; the analytical procedures are selected from the stated test method designations where applicable.

Species-level inclusion is normally defined by the veterinary feed dossier rather than the API. Representative target counts in complete feed are 1.0 × 10⁸ to 5.0 × 10⁸ CFU/kg for poultry, 2.0 × 10⁸ to 1.0 × 10⁹ CFU/kg for swine, and 1.0 × 10⁹ to 5.0 × 10⁹ CFU/kg for aquaculture feeds. These are starting-point inclusion rates after dilution; recovery after extrusion or pelleting must be confirmed in the final matrix because free moisture, conditioner temperature, and pressure affect spore survival. The concentrated API is first diluted into a carrier premix at 1:100 or 1:1000 before feed addition; this dilution step reduces segregation risk and improves analytical counting precision. Poultry applications under heat stress or coccidial challenge often use 3.0 × 10⁸ CFU/kg complete feed; piglet creep feeds use 2.0 × 10⁸ to 5.0 × 10⁸ CFU/kg, and aquaculture extruded feeds that reach preconditioner temperatures of 110–130 °C are usually supplemented by vacuum coating or post-extrusion oil coating at ≤ 40 °C.

When Live Clostridium butyricum API Is Chosen Over Vegetative Probiotic Strains

Selection intent is process survival under thermal load and distal intestinal butyrate availability, not general probiotic equivalence. Vegetative Lactobacillus and Bifidobacterium preparations typically lose 2–4 log CFU/g during feed pelleting at 80 °C for 30 s; the spore fraction of Clostridium butyricum API shows losses below 1 log under the same conditions when premix moisture is maintained at 10–12%. Clostridium butyricum is an anaerobe; the spore is oxygen-tolerant during handling, but germination and butyrate production require the low redox environment of the distal intestine. Bacillus subtilis shares the spore-survival advantage but does not produce butyrate as a primary fermentation end product. Sodium butyrate salts release butyrate in the upper digestive tract and are pH-dependent; the live API releases butyrate only after germination and substrate fermentation, which locates the effect more distally but also makes the dose-response curve dependent on endogenous substrate availability.

Formulators should not regard the live API as equivalent to a chemically defined butyrate source in immediate-release oral solutions. The time to initial butyrate production in vivo depends on gastric emptying, spore germination rate, and available fermentable carbohydrate; published data for this specific model in target species are limited, and in vitro batch fermentation assays on standard reinforced clostridial medium may overestimate in vivo kinetics. Compatibility with clostridial-active antimicrobials such as metronidazole or high-dose amoxicillin must be demonstrated for the final formulation unless the antimicrobial is administered separately. Medicated premix containing zinc oxide above 2500 mg/kg may reduce recoverable CFU by 0.5–1.0 log in swine nursery formulations; this interaction is quantified in a matrix-specific recovery study before the final inclusion rate is fixed.

Spore survival drops steeply when post-pelleting moisture exceeds 12% and cooling air velocity exceeds 1.5 m/s

Feed-mill integration is validated with a horizontal ribbon mixer of 500–1000 kg working volume and a tip speed below 1.0 m/s. High-shear mixing above 1.5 m/s or mixing beyond 15 min has been linked to carrier attrition and moisture migration, reducing spore recovery in premix samples by 0.2–0.5 log. Post-pelleting liquid application is performed on cooled pellets at ≤ 40 °C; the spore suspension is sprayed and the target dose verified by extracting 10 g samples in chilled buffer and plating within 2 h. In low-shear granulation for tablet manufacture, the API is added after the wet mass has cooled below 35 °C because binder solutions above 50 °C can induce premature germination, and germinated cells are inactivated during subsequent drying. The bulk API stability protocol in sealed aluminium-laminated foil pouches at 25 °C / 60% RH uses time points at 0, 3, 6, 12, 18, and 24 months; typical spore count loss is 0.3 log at 12 months and 0.8 log at 24 months when the pouch is not resealed after first use.

Storage of unopened bulk API at 4 °C extends count retention; open containers should be avoided because moisture uptake above 7.0% accelerates caking and reduces flowability. Finished feed with moisture above 14% and water activity above 0.7 can support spore germination during storage, after which the resulting vegetative cells lose viability during transport; low-moisture cereal carriers and moisture-barrier packaging are therefore specified for all premix blends. Quality risk assessment for the API follows veterinary GMP and evaluates residual DNA, antimicrobial resistance gene transfer risk, and toxigenic potential in the master file. The manufacturing process includes a sporulation efficiency check; if the spore-to-vegetative-cell ratio is below 90%, the batch is rejected or reprocessed after additional incubation with carbohydrate limitation. This release criterion reduces batch-to-batch variation in thermal tolerance and storage stability.