Method for determination of histidine in tissues by isocratic high-performance liquid chromatography and its application to the measurement of histidinol dehydrogenase activity in six cattle organs.

A selective and simple HPLC procedure has been developed to determine histidine (His) and histidinol (HDL) in liver supernate. The separation was performed on a column, Mightysil RP-18 GP. The eluted analytes were measured with UV detection without derivatization which provided detection limits of 1.1 and 2.0 microM for His and HDL (S/N ratio, 3:1), respectively. Recovery of the analytes added to liver sample was 98.3-101.6% within a 1-day study and 95.7-98.6% on different day (6 days) studies. The apparent histidinol dehydrogenase activities (nmol/g wet tissue) at pH 8, 9, 10, 11, and 12 were 38.6, 50.4, 160.3, 274.3, and 185.6 for liver; 90.6, 132.2, 30.7, 22.1, and 6.76 for kidney; 0.0, 0.0, 38.2, 20.1, and 12.9 for pancreas; 0.0, 0.0, 0.0, 14.7, and 6.8 for spleen; 0.0, 0.0, 4.2, 6.8, and 0.0 for muscle; and 0.0, 0.0, 4.9, 1.8, and 0.0 for small intestine, respectively. On the basis of optimum pH values, histidinol dehydrogenase activity in the organs was in the following order: liver>kidney>pancreas>spleen>muscle>small intestine.

Tryptophan biosynthesis and production of other related compounds from indolepyruvic acid by mixed ruminal bacteria, protozoa, and their mixture in vitro.

Tryptophan (Trp) biosynthesis and the production of other related compounds by mixed ruminal bacteria (B), protozoa (P), and their mixture (BP) in an in vitro system were quantitatively investigated by using 1 mM of indole-3-pyruvic acid (IPA) as substrate. Ruminal microorganisms were anaerobically incubated at 39 degrees C for 12 h. Trp and other related compounds in both the supernatants and the microbial hydrolyzates of the incubation were analyzed by HPLC. As a whole, about 334, 440, and 436 &mgr;M of Trp were produced from IPA in 12 h by B, P, and BP suspensions, respectively. In the B suspension, a greater portion of synthesized Trp (242 &mgr;M) from IPA was accumulated as free form in the medium, whereas a large amount of Trp (92 &mgr;M) was incorporated into cell protein in a 12-h incubation. On the other hand, in the P suspension, a large amount of Trp (475 &mgr;M) from IPA was also found as free form in the supernatant in a 12-h incubation. Protozoa did not incorporate Trp into cell protein, but they liberated endogenous Trp (34 &mgr;M) into the medium. The net productions of Trp from IPA were 344.3 and 447.7 &mgr;mol/g of microbial nitrogen in 12 h by B and P suspensions, respectively. The ability of P to synthesize Trp from IPA was about 30% higher than that of B in 12 h. Trp produced from IPA by B, P, and BP suspensions were simultaneously degraded into its related compounds, and among them, indoleacetic acid (IAA) was a major product found in all microbial suspensions. Productions of IAA were 124, 25, and 99 &mgr;M from IPA in 12 h by B, P, and BP suspensions, respectively. The formation of indolelactic acid (ILA) from IPA was observed for the first time in all microbial suspensions, and it was about 84, 24, and 54 &mgr;M in 12 h by B, P, and BP, respectively. Higher IAA and ILA productions were observed in B when compared with P. A small amount of skatole (SKT) (26 &mgr;M) was produced from IPA in B, whereas a sizable amount of SKT (38 &mgr;M) was found in BP after a 12-h incubation. p-Cresol (CRL) was also produced from IPA by both B (43 &mgr;M) and BP (65 &mgr;M) suspensions in 12 h, and this is also the first discovery to show the formation of CRL from IPA by B and BP suspensions. BP suspension was more active to produce both SKT and CRL from IPA, though P suspension has no ability to produce either SKT or CRL from IPA during a 12-h incubation.

A comparative evaluation of Cephalosporin C production using various immobilization modes.

The production of Cephalosporin C was investigated in a lab-scale 1.4 l air-lift reactor (ALR), using various immobilization modes. Bioparticles were developed by forming biofilm of growing hyphae around an inorganic siran particle which contained spores of the organism. Silk sachet was the other immobilization matrix. The maximum specific growth rate of the Cephalosporium acremonium, free cells, pellets, siran carrier and silk sachets were 0.037, 0.003, 0.047, and 0.035 h(-1), and specific antibiotic productivities (as compared to 100% for free cells) were 180, 150, and 125% for siran carrier, silk sachets and pellets, respectively. Immobilization modes exhibited enhanced volumetric oxygen transfer coefficient and well-controlled, three-phase hydrodynamics.

Effects of salinomycin and vitamin B(6) on in vitro metabolism of phenylalanine and its related compounds by ruminal bacteria, protozoa and their mixture.

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 degrees 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 &mgr;M 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 (p<0.05) by 40, 20 and 19% in B, P and BP, respectively, while PAA production from PPY with SL was inhibited (p<0.05) 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 &mgr;M and converted mainly to Phe on the average by 231, 244 and 248 &mgr;M in B, P and BP, respectively. The disappearance of PAA with SL was inhibited (p<0.05) by 16, 15 and 20%, in B, P and BP, respectively, whereas the disappearance of PAA with B6 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 production from PAA with B(6) tended to be enhanced by 13, 16 and 8% in B, P and BP, respectively. When Phe was added as a substrate, the net Phe disappearance without additives was 549, 365 and 842 &mgr;M and converted mainly to PAA on the average by 254, 205 and 461 &mgr;M in B, P and BP, respectively. The net disappearance of Phe with SL was inhibited (p<0.05) by 38, 28 and 46%, whereas the net disappearance of Phe with B(6) was enhanced (p<0.05) by 9, 8 and 7% in B, P and BP, respectively. The production of PAA from Phe with SL was inhibited (p<0.05) by 73, 54 and 76% in B, P and BP, respectively. On the other hand, with B(6), PAA production from Phe was enhanced (p<0.05) by 19, 18 and 20% in B, P and BP, respectively. Based on these results, it seems that SL inhibited Phe disappearance and enhanced the synthesis of Phe from PPY, though not from PAA, and accumulated free Phe in the medium, whereas B(6) also enhanced Phe synthesis both from PPY and PAA, which could provide additional amino N for animals.

In vitro metabolism of phenylalanine by ruminal bacteria, protozoa, and their mixture.

An in vitro study was conducted to examine the metabolism of phenylalanine (Phe) by mixed rumen bacteria (B), mixed rumen protozoa (P), and a combination of the two (BP). Rumen microorganisms were collected from fistulated goats fed lucerne cubes (Medicago sativa) and a concentrated mixture twice a day. Microbial suspensions were anaerobically incubated at 39 degrees C for 12 h. Phe and some other related compounds in both supernatants and microbial hydrolysates of the incubations were analysed by HPLC. The net degradation rate (&mgr;mol/g microbial nitrogen) of Phe in B was about 1.5-fold higher than that in P. Phe was converted mainly into phenylacetic acid (PAA) and unknown compound(s) that presumably involved tyrosine in B, P, and BP during the 12 h incubation period. Small amounts of benzoic acid (BZA), and traces of phenylpropionic acid (PPR) and phenyllactic acid (PLA) were also produced from Phe. PAA production in B was found to be higher than that in P, whereas it was significantly higher in BP. Although BZA production was less than one-tenth that of PAA production, it was higher in P than in B and BP. PPR was detected in both B and BP, but not in P. PLA was detected only in B. The production of unknown compound(s) was higher in B than in P and BP.

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

Phenylalanine (Phe) synthesis and the production of other related compounds by mixed ruminal bacteria (B), protozoa (P), and a combination of the two mixture (BP) in an in vitro system were quantitatively investigated using phenylpyruvic acid (PPY) and phenylacetic acid (PAA) as substrates. Rumen microorganisms were collected from fistulated goats fed lucerne cubes (Medicago sativa) and a concentrated mixture twice a day. Microbial suspensions were anaerobically incubated at 39 degrees C for 12 h. Phe and some other related compounds in both supernatants and microbial hydrolysates of the incubations were analysed by HPLC. A large quantity of Phe was produced from both PPY and PAA not only in B but also in P. In B suspensions, free Phe also accumulated in the medium only when PPY was used as a substrate. The ability of B to synthesize Phe from both PPY and PAA (expressed as unit 'per microbial nitrogen') was 5.1 and 24.8% higher than P, respectively. Phe production from PPY in B and P was 43.5 and 55.2% higher than that from PAA. Large amounts of PAA (17-27%) were produced from PPY in all microbial suspension and production amounts were similar in B and P. Small amounts of benzoic acid (BZA) were produced from PPY and PAA in B, P, and BP, and higher BZA production was observed in P as compared to B. Phenylpropionic acid (PPR) was produced in B from both PPY and PAA, but not in P or BP. A trace amount of phenyllactic acid (PLA) was detected only from PPY in B. Higher concentrations of an unknown compound from PPY and PAA were found to be accumulated in the body protein of B and also in the medium of P, and production of the compound from both PPY and PAA was also higher in B than P.