Propionibacteria as inoculants to high-moisture corn

Two studies were conducted to evaluate the efficacy of propionibacteria as silage inoculants. In the first study, the performance of propionibacteria with or without lactic acid bacteria were evaluated. Results showed that propionibacteria enhanced the fermentation of reconstituted corn only up d 21 of ensiling. The combination of P. acidipropionici DH42 with lactic acid bacteria as inoculants reduced silage pH and butyric acid and increased propionic, acetic and lactic acids. LAB inoculation did not significantly increase the LAB population in the treated silages. During aerobic exposure, all the silages appeared well-preserved. Organic acid levels remained stable throughout the exposure period. Propionibacteria inoculation did not significantly reduce the yeast and mold population. However, the silages with P. acidipropionici DH42 + LAB had higher propionic, acetic and lactic acids and lower pH.; In the second study, the effect of moisture on the efficacy of propionibacteria as silage inoculants was tested. Rolled corn of moisture contents ranging from 22–35% were used. The 22–28% moisture levels appeared to favor the growth of the P. acidipropionici DH42 in silage. After 120 d of ensiling, PAB-inoculated high moisture corn gave higher propionic and acetic acids and lower pH and butyric acid at 22–28%. P. acidipropionici DH42 inoculated at 106cfu/g better gave results as compared to the 105cfu/g. During aerobic exposure, higher propionic and acetic acids and lower pH were observed with the PAB-treated silages from the 22–28% moisture levels. Propionibacteria inoculation did not significantly reduce yeast and mold counts.; The vitamin B₁₂ production capability of P. acidipropionici DH42 was also evaluated in comparison with P. shermanii . Results showed comparable vitamin B₁₂ production of the two propionibacteria strains. After 72 h of incubation, the P. acidipropionici DH42 and P. shermanii cultures grown at 30°C had vitamin B₁₂ contents of 852.85 and 840.69 ng/ml, respectively. Both strains grew better at 30°C than at 40°C. P. acidipropionici DH42 cultures tend to have higher propionic and acetic acids while the P. shermanii cultures had higher succinic and malic acids.; A PCR-based detection of P. acidipropionici DH42 was developed. Nested PCR was used with DH42-specific primers dhb1 and dhb2 for the secondary amplification of a 1,267 bp-fragment. Using the established protocols for PCR amplification, as low as 102cfu/ml and 10 3cfu/ml of P. acidipropionici DH42 in silage extracts and rumen fluid, respectively, were detected.; The silage studies had shown that moisture level affects the efficacy of P. acidipropionici DH42. The 22–28% moisture content appears to favor its growth. An inoculation rate of 106cfu/g of ensiling material is recommended. P. acidipropionici DH42 can produce vitamin B₁₂ that is comparable to P. shermanii's producing capability. Moreover, P. acidipropionici DH42 can be detected in silage and rumen fluid samples using PCR technology.