Effects of salinomycin and vitamin B6 on in vitro metabolism of phenylalanine and its related compounds by ruminal bacteria, protozoa and their mixture.

Abstract

Several ionophores, such as salinomycin (SL), monensin, lasalocid, and tetronasin, have been shown to favorably alter ruminal fermentation characteristics and metabolism (Bergen and Bates, 1984;Chen and Wolin, 1979;Newbold et al., 1988;Russell and Strobel, 1989;Russell et al., 1991;Schelling, 1984). The curative effects of SL on coccidiosis (Merchen and Berger, 1985) and feedlot bloat, negative effects on the in vivo total counts of Gram-positive cocci Effects of salinomycin and vitamin B 6 on in vitro metabolism of phenylalanine and its related compounds by ruminal bacteria, protozoa and their mixture M. Ruhul Amin* and Ryoji Onodera Laboratory of Animal Nutrition and Biochemistry, Division of Animal Science, Miyazaki University, Miyazaki 889-2192, Japan (Received December 9, 1996; Accepted September 25, 1997) An in vitro study was conducted to examine the effects of salinomycin (SL) and vitamin B 6 (B 6 ) on the production of phenylalanine (Phe) from phenylpyruvic acid (PPY) and phenylacetic acid (PAA) and of PAA from Phe and PPY by mixed rumen bacteria (B), mixed rumen protozoa (P) and their mixture (BP). Rumen microorganisms were collected from fistulated goats fed lucerne cubes (Medicago sativa) and a concentrate mixture (3 : 1) twice a day. Microbial suspensions were anaerobically incubated at 39°C for 12 h. Phe and some other related compounds in both supernatants and microbial hydrolysates of the incubations were analyzed by HPLC. When PPY was used as a substrate, it completely disappeared without additives and converted mainly to Phe and PAA on the average by 396 and 178, 440 and 189, and 439 and 147 µ µM in B, P and BP, respectively, during the 12 h incubation period. The rate of disappearance showed no significant differences between the microbial suspensions with and without SL and B 6 during the incubation period. The production of Phe from PPY with SL was enhanced (pϽ0.05) by 40, 20 and 19% in B, P and BP, respectively, while PAA production from PPY with SL was inhibited (pϽ0.05) by 35, 37 and 38% in B, P and BP, respectively, during the 12 h incubation period. On the other hand, with B 6 , the production of Phe and PAA from PPY tended to be enhanced by 14 and 17, 9 and 11, and 7 and 22% in B, P and BP, respectively, during the 12 h incubation period. When PAA added as a substrate was incubated in the incubation medium without any additives, it disappeared by 483, 462 and 507 µ µM and converted mainly to Phe on the average by 231, 244 and 248 µ µM in B, P and BP, respectively. The disappearance of PAA with SL was inhibited (pϽ0.05) by 16, 15 and 20%, in B, P and BP, respectively, whereas the disappearance of PAA with B 6 was almost the same as that without B 6 in B and BP suspensions but tended to be enhanced by more than 9% in P suspensions during the 12 h incubation period. The production of Phe from PAA with SL tended to be inhibited by 12, 11 and 8% in B, P and BP, respectively, during the 6 h incubation period, but the inhibition was weakened during the 12 h incubation period, whereas Phe...

Synthesis of phenylalanine and production of other related compounds from phenylpyruvic acid and phenylacetic acid by ruminal bacteria, protozoa, and their mixture in vitro.

“…BZA production from Phe by mixed rumen microorganisms (Amin et al, 1994;Scott et al, 1964) and B and P (Amin et al, 1994) were demonstrated previously, but the formation of BZA from PPY and PAA by B, P, and BP, as indicated in this experiment, is the first evidence.…”

“…In this experiment, BZA production from PAA per gram MN was 2.0-and 1.4-fold higher in P than in B and BP, respectively. The lower production of BZA from PAA in the BP suspensions was justified by mechanical calculation because B have a lower ability to produce BZA from PAA than P. The production of BZA from Phe was also higher in P in our previous report (Amin et al, 1994).…”

“…It also suggests that the predation of protozoa can decrease the number of bacteria in the mixed microbial suspensions, and result in the decrease of total bacterial activity to convert PAA from Phe. PAA production from Phe by rumen bacteria (Amin et al, 1994;Van Den Hende et al, 1964), mixed rumen microorganisms (Amin et al, 1994;Patton and Kesler, 1967;Scott et al, 1964), rumen protozoa Entodinium caudatum (Coleman, 1967), and mixed rumen protozoa (Amin et al, 1994) has already been demonstrated. The production of PAA from PPY by ruminal B, P, and BP in this experiment was the first evidence.…”

“…In vitro productions of PPR from Phe by mixed rumen microorganisms (Amin et al, 1994;Scott et al, 1964), mixed rumen bacteria (Amin et al, 1994) and Clostridium sp. (Elsden et al, 1976;Moss et al, 1970) were demonstrated previously, but the production of PPR from PPY and PAA by rumen bacteria was first demonstrated in this experiment.…”

“…The formation of PAA from Phe by mixed rumen bacteria, protozoa and a combination of the two has been demonstrated previously (Amin et al, 1994), but the formation of PAA from PPY has not yet been examined.…”