Amino acids that were utilized as sole sources of carbon and nitrogen for growth of Serratia marcescens Nima resulted in biosynthesis of prodigiosin in non-proliferating bacteria. Addition of alanine, proline, or histidine to non-proliferating cells incubated at 27 C increased the rate of protein synthesis and also caused biosynthesis of prodigiosin. No increase in the rate of protein synthesis was observed upon the addition of amino acids that did not stimulate prodigiGsin biosynthesis. Increased rates of synthesis of ribonucleic acid (RNA) and of deoxyribonucleic acid (DNA) (a small amount) also occurred after addition of amino acids that resulted in biosynthesis of prodigiosin. After incubation for 24 h, the total amount of protein in suspensions of bacteria to which alanine or proline was added increased 67 and 98%, respectively. Total amounts of DNA and of RNA also increased before synthesis of prodigiosin. The amounts of these macromolecules did not increase after addition of amino acids that did not induce biosynthesis of prodigiosin. However, macromolecular synthesis was not related only to prodigiosin biosynthesis because the rates of DNA, RNA, and protein synthesis also increased in suspensions of bacteria incubated with proline at 39 C, at which temperature no prodigiosin was synthesized. The quantities of DNA, RNA, and protein synthesized were lower in non-proliferating cells than in growing cells. The data indicated that amino acids causing biosynthesis of prodigiosin in non-proliferating cells must be metabolized and serve as sources of carbon and of nitrogen for synthesis of macromolecules and intermediates. Prodigiosin was synthesized secondarily to these primary metabolic events.

Mutants ofSerratia marcescens Nima, designated as Aut, Hut, or Put, did not utilize L-alanine, L-histidine, or L-proline, respectively, as a sole carbon source but did utilize other amino acids or glycerol as carbon sources. The bacteria were permeable to alanine, histidine, and proline but lacked the enzymes responsible for degradation of these amino acids. The Aut mutant contained no L-alanine dehydrogenase activity, whereas the Hut and Put mutants contained only 7 and 4% of the histidase and proline oxidase activities, respectively, found in the wildtype strain. Rates of oxygen uptake and protein synthesis were significantly lower when the mutants were incubated in the presence of amino acids they could not degrade. Studies of i_['4C]alanine, L-[14C]histidine, and L-['4C]proline

A Put mutant of Serratia marcescens, deficient in proline oxidase and therefore unable to degrade proline, was used to assay for an enzymatic reaction responsible for incorporation of proline into prodigiosin. The reaction had a pH optimum of 7.5 and a Km of 1.1 x 10-4 M at 27 C. At temperatures above 27 C, the velocity of the reaction decreased with increasing temperature and little activity was detected at 42 C. Activity of the enzyme was directly proportional to the quantity of pigment formed and was inhibited by thioproline, a substrate analog. These data suggested the presence of a unique and specific enzyme in the biosynthetic pathway for prodigiosin.

The dried root of Angelica gigas (A. gigas) has been traditionally used as an oriental medicine, which is known to improve blood circulation and blood stasis. In the present study, leaves and stalks of A. gigas were used to investigate their effects on the innate immunity. The extracts were prepared from leaves and stalks of A. gigas and were fed to mice. The numbers of blood cells, total WBCs, neutrophils, lymphocytes, eosinophils and basophils were increased by 50% in mice fed with leaves extract of A. gigas compared to control mice. However, the numbers of blood cells were decreased when treated with stalks extract of A. gigas. The level of cholesterol and triglyceride in serum was markedly reduced in both mice group fed with leaves extract and stalks extract of A. gigas compared to control group (P＜0.01). There was no significant change in the level of albumin, total protein, phosphate and calcium in serum. Activity of cationic peptide was found to be diffused in the testicles of mice fed with leaves extract of A. gigas compared to control group, which might be due to increased lysozyme in testicle. The lysoplate assay and immunohistochemistry assay suggest that the extract of leaves and stalks of A. gigas are immunogenic, but the effects might be related with acquired immune response rather than innate immunity.