Carotenoid pigment is an essential element in aquaculture, since it gives characteristic of color on shrimp and fish. Carotenoid pigments can be produced microbiologically using Paffia rhodozyma . Genetic improvement of the yeast, one of which can be accomplished by radiation mutation, will increase the production of carotenoid pigments. The aims of this study were to mutate P. rhodozyma using UV irradiation and to figure out pigment production by the mutant strains resulting from 30 minute-irradiation. Irradiated culture was incubated in dark condition and plated onto YMA media. Grown mutant colonies were collected in order to test for their pigment production. Pigment production was measured on the basis of extinction coefficient of 1%. The results showed that mutant strain encoded with MUV-1 produced the highest pigment at mg/g dry weight cell, higher than the wild type ( mg/g dry weight cell).
carotenoid, Paffia rhodozyma pigment, radiation, mutation
Teks Lengkap: PDF Referensi
An ., . Schuman, and . Johnson. 1989. Isolation of Phaffia rhodozyma mutans with increased astaxanthin content. Appl. Envinron. Microbiol. 55: 116-124.
Pseudomonas sp. is one of bacterial groups having ability to promote plant growth and health. Of a hundred successfully isolated Pseudomonas sp. from soybean rhyzosphere, 98 were found to produce indole acetic acid (IAA) ranging from to ppm. These isolates are bacilli, motile, Gram negative, and showing positive oxidase assay. One of them, . Pseudomonas sp. CRB17, can promote plant growth by means of significant stimulation of primary root length and lateral root number. This isolate was then subject to mutagenesis using transposon Mini-Tn5Km1 to increase IAA production. Mutagenesis was done by conjugation between E coli S17-1 (l pir) carrying transposon mini-Tn5Km1 (donor) and Pseudomonas sp. (recipient), resulting in conjugation frequency of approximately x 10 -5 cell per recipient. The resulted CRB17 mutants were then tested for their ability to produce IAA, one of which showed an increment of IAA production up to %, while some others showed no significant change or even had a reduction to %. Sequence analyisis of 16S rRNA gene of Pseudomonas sp. CRB17 indicated that it has a high homology with that of Pseudomonas plecoglossicida (identical value of 99%). The results recommends that mutagenesis using transposon can be applied to increase IAA production, especially in Pseudomonas sp. CRB17.
Xanthone production in Hypericum perforatum (HP) suspension cultures in response to elicitation by Agrobacterium tumefaciens co-cultivation has been studied. RNA blot analyses of HP cells co-cultivated with A. tumefaciens have shown a rapid up-regulation of genes encoding important enzymes of the general phenylpropanoid pathway (PAL, phenylalanine ammonia lyase and 4CL, 4-coumarate:CoA ligase) and xanthone biosynthesis (BPS, benzophenone synthase). Analyses of HPLC chromatograms of methanolic extracts of control and elicited cells (HP cells that were co-cultivated for 24h with A. tumefaciens) have revealed a 12-fold increase in total xanthone concentration and also the emergence of many xanthones after elicitation. Methanolic extract of elicited cells exhibited significantly higher antioxidant and antimicrobial competence than the equivalent extract of control HP cells indicating that these properties have been significantly increased in HP cells after elicitation. Four major de novo synthesized xanthones have been identified as 1,3,6,7-tetrahydroxy-8-prenyl xanthone, 1,3,6,7-tetrahydroxy-2-prenyl xanthone, 1,3,7-trihydroxy-6-methoxy-8-prenyl xanthone and paxanthone. Antioxidant and antimicrobial characterization of these de novo xanthones have revealed that xanthones play dual function in plant cells during biotic stress: (1) as antioxidants to protect the cells from oxidative damage and (2) as phytoalexins to impair the pathogen growth.