CLOSTAT® Active Microbial
CLOSTAT® contains a proprietary, patented strain of Bacillus subtilis, PB6. PB6 is a unique, naturally occurring spore-forming microorganism. Kemin has identified and selected the specific strain of PB6 isolated from the gut of a healthy chicken surviving a necrotic enteritis outbreak. PB6 secretes an active substance that helps maintain the balance of microflora in the intestinal tract of livestock, poultry and equine.
PB6 has been tested by Kemin in various species of animals to show its benefits in the inhibition of pathogens. By inhibiting pathogens in the intestinal tract of livestock and poultry, PB6 can help improve gut health and overall efficiency.
In 2002, Kemin Industries isolated a Bacillus bacterium, which was identified and registered as Bacillus subtilis, PB6.1 That same year, a study was conducted that provided the Kemin R&D laboratory 13 isolates obtained from diagnostic field cases. The objective was to evaluate the inhibitory activity of PB6 on clostridial isolates from poultry via well diffusion assays.
As shown in Table 1, PB6 inhibited growth of all poultry isolates provided for analysis. The degree of inhibition is noted in clearing area (mm) and as a percentage compared to the antibiotic chloramphenicol (positive control). The degree of growth inhibition varied with each isolate.
Table 1. Effect of PB6 on growth inhibition of C. perfringens, c. septicum, and C. sordellii poultry isolates. Well diameters represent single to an average of three measurements.2
UGA - University of Georgia, Poultry Diagnostic Research Center
UMN - University of Minnesota, Veterinary Diagnostic Lab
UARK - Univeristy of Arkansas
Again in 2002, Kemin R&D conducted a similar study with a total of 7 isolates (C. perfringens and C. difficile) obtained from diagnostic field cases. The objective of the study was to evaluate the inhibitory activity of PB6 against clostridial isolates from swine via counter streak and/or well diffusion assays.
The objective of these assays was to evaluate the ability of PB6 to inhibit the growth of Clostridium spp. isolated from swine diagnostic cases, not to compare the sensitivity of one Clostridium sp. to another. Examples of each assay are shown in Figure 1. Clostridium perfringens inhibition is noted by the zones of inhibition (A) in a well diffusion assay and areas of clearing (B) as noted in a streak assay.
Figure 1. Examples of C. perfringens inhibition by PB6 as observed in both well diffusion (A) and streak (B) assays.3, 4
In another study, a series of microbial inhibition function assays were conducted to evaluate PB6 as compared to four commercially available direct-fed microbials (DFM) Materials (noted as A, B, C, and D).
The inhibition by the bacterial cultures of the DFM Material (D) and PB6 toward the growth of Clostridium perfringens UGA49824 as tested by a double bacterial counter streak assay is presented in Figure 2. The streak assay shows that PB6 had a larger zone of inhibition than DFM Material (D) in this assay.
Figure 2. Zones of inhibition agains growth of C. perfringens UGA49824 by a streak line assay (Material D noted as  and PB6 noted as ).
Suggested Feeding Rates
Swine and Poultry: 1 lb per ton of finished or complete feed
Equine: 2.5-4 lbs per ton of finished or complete feed
CLOSTAT is sold in 25 kg bags. Store in a cool, dry place out of direct sunlight for maximum shelf life.
- PTA-6737ATCC. American Type Culture Collection, Manassas, Virginia.
- Kemin Internal Document 09-00010
- Kemin Internal Document 09-00008
- Kemin Internal Document 09-00004