Separation of Prodigiosenes and Identification as Prodigiosin Syntrophic Pigment from Mutant Pairs of Serratia marcescens

Countercurrent distribution is capable of resolving mixtures of closely related prodigiosene pigments. Syntrophic pigment produced by several pairs of Serratia marcescens color mutants was identified as prodigiosin (2-methyl-3-amyl-6-methoxyprodigiosene) by countercurrent distribution, soda lime pyrolysis, and other techniques. The metabolic block of mutant strain H-462, derived from parent strain HY, was located between the blocks of mutant strains OF and WF, both derived from parent strain Nima.     

Changes in Myxococcus xanthus pigments induced by phosphate and temperature

Pigment levels have been measured in a number of wild strains and colour mutants of Myxococcus xanthus . The non-carotenoid yellow pigment and carotenoid pigment contents changed according to growth temperature and phosphate concentrations in liquid media. The highest content of both types of pigment was observed at 28°C with all strains. A high phosphate concentration depressed pigment content in both wild and mutant strains at all temperatures, except with two colour mutants, where the pigments levels remained unchanged at 28°C and 33°C.     

产氢红杆菌类胡萝卜素突变株的诱变和筛选

用紫外线照射和氯化锂夹层平板培养法对产氢红杆菌(Rhodobacter sp. R7)进行复合诱变, 分离获得了一株产氢效率提高的类胡萝卜素突变株R726。该突变株在表观特征、光谱学特征、色谱特征、生长和产氢性能等方面与出发菌株有明显不同, 但16S rDNA序列一致。R726菌株有 550 nm类胡萝卜素特征性吸收峰, 类胡萝卜素组成上比出发菌株少一黄色类胡萝卜素组分, 生长和产氢性能均高于出发菌株, 产氢效率比出发菌株提高了33.3%, 类胡萝卜素含量比出发株提高了53.8%。     

产氢红杆菌类胡萝卜素突变株的诱变和筛选

用紫外线照射和氯化锂夹层平板培养法对产氢红杆菌(Rhodobacter sp.R7)进行复合诱变,分离获得了一株产氢效率提高的类胡萝卜素突变株R726.该突变株在表观特征、光谱学特征、色谱特征、生长和产氢性能等方面与出发菌株有明显不同,但16S rDNA序列一致.R726菌株有550 nm类胡萝卜素特征性吸收峰,类胡萝卜素组成上比出发菌株少一黄色类胡萝卜素组分,生长和产氢性能均高于出发菌株,产氢效率比出发菌株提高了33.3%,类胡萝卜素含量比出发株提高了53.8%.     

The use of cellulases from a beta-glucosidase-hyperproducing mutant of Trichoderma reesei in simultaneous saccharification and fermentation of wheat straw

Conidia of the cellulolytic strain Trichoderma reesei F522 were mutagenized with UV irradiation and N-methyl|-N'-nitro-N-nitrosoguanidine (NTG). A visual agar plate detection system was developed, using esculin and ferric ions, to identify mutants of T. reesei with increased beta-glucosidase activity. Selected mutants were tested for production of extracellular cellulases in shake flasks on autohydrolyzed wheat straw as carbon source. The most active mutant V-7 showed about 6-times higher activity of beta-glucosidase than the parent strain F-522, whereas the filter paper degrading and endo-1,4-beta-D-glucanase activities increased by 45% and by almost 31%, respectively. Cellulase preparations obtained from the parent and mutant strains were then used along with Kluyveromyces fragilis cells for ethanol production from ethanol-alkali pulped straw in the simultaneous saccharification and fermentation (SSF) process. From 10% (w/v) of straw pulp (dry matter), 2.5% (w/v) ethanol was obtained at 43 degrees C after 48 h using cellulase derived from the parent strain of T. reesei. When the beta-glucosidase-hyperproducing mutant V-7 was employed, the ethanol yield in the SSF process increased to 3.4% (w/v), the reaction time was shortened to 24 h and no cellobiose was detected in straw hydrolyzates.     

Nutritional control of the frequency of MNNG-induced true branching habit in Anabaena doliolum

Summary MNNG survival and mutagenesis were studied in Anabaena doliolum Bharadwaja. The survival curves of germinating spores were exponential while those of resting spores and filament-fragments were sigmoidal. Blue mutants with much higher phycocyanin contents than the parent were recovered in varying frequencies; the frequency (1.1%) was the highest with 2 mg/ml MNNG for 15 min. Some of the blue mutants sporulated normally; while others did not. A nonsporulating blue mutant (M16) showed branched filaments in liquid cultures. In nitrogen free medium. M16 had a high frequency (70%) of branched filaments during the early phase of growth. In some filaments, the branch arose from a heterocyst showing three polar nodules. There was no other difference between the parent and the mutant in cell morphology and cellular differentiation. High light intensity adversely affected phycocyanin and chlorophyll a pigments and nitrogen fixation in the mutant. Frequency of mutant branched character appears to beta factor of inorganic nitrogen nutrition.Dedicated to the memory of my revered teacher the late Prof. R. N. Singh     

Strain improvement of Candida tropicalis for the production of xylitol: biochemical and physiological characterization of wild-type and mutant strain CT-OMV5

Candida tropicalis was treated with ultraviolet (UV) rays, and the mutants obtained were screened for xylitol production. One of the mutants, the UV1 produced 0.81 g of xylitol per gram of xylose. This was further mutated with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), and the mutants obtained were screened for xylitol production. One of the mutants (CT-OMV5) produced 0.85 g/g of xylitol from xylose. Xylitol production improved to 0.87 g/g of xylose with this strain when the production medium was supplemented with urea. The CT-OMV5 mutant strain differs by 12 tests when compared to the wild-type Candida tropicalis strain. The XR activity was higher in mutant CT-OMV5. The distinct difference between the mutant and wild-type strain is the presence of numerous chlamydospores in the mutant. In this investigation, we have demonstrated that mutagenesis was successful in generating a superior xylitol-producing strain, CT-OMV5, and uncovered distinctive biochemical and physiological characteristics of the wild-type and mutant strain, CT-OMV5.     

Growth,differentiation and secondary metabolites of colour mutants ofTrichoderma viride

The parental strainTrichoderma viride and 3 colour mutants (milk white, yellow and brown) blocked at various stages of colony pigmentation derived from it were characterized. The parental strain and the mutants exhibited different growth rates. The identical type of induced fluorescence was observed in all the strains. Hyphae and septa lighted first, whereas reproduction structures did not; after treatment with fluorescein-isothiocyanate and Blankophor RKH the growing hyphal apices were accentuated. In the mutants conidiation was induced at 1-, 2- and 3-d intervals, similarly to the parent strain. Pigmentation of conidiation rings depended on their type and age. The yellow and brown mutants excreted chromatographically different pigments, extractable with ethylacetate, into the medium. Two anthraquinone pigments,viz. 1,3,6,8-tetrahydroxyanthraquinone (1) and 1-acetyl-2,4,5,7-tetrahydroxyanthraquinone (2) were isolated from the brown mutant (Betinaet al. 1986).     

Mutant Bac. subtilis A2 with an enhanced capacity to induce an adaptive response

Mutant A2 with increased ability to induce adaptive response was isolated in Bac. subtilis and its properties studied. Mutant A2 was shown to be more resistant to mutagenic action of MNNG, EMS, UV light. It was also discovered that A2 was more sensitive to the lethal action of MNNG and UV light than parent strain 103. It was shown by clonal analysis of mutant colonies, formed by mutant cells A2 and 103 that A2 strain had increased ability to form complete mutants. Properties of A2 mutant suggest that in the process adaptive response induction were is expression of both adaptive response enzymes and some other which are necessary for reparation of premutagenic UV lesions.     

Ultraviolet induced mutations in Aspergillus wentii.

Aspergillus wentii (IMI 17295) and its three nutritional mutant strains were irradiated with UV rays. New mutants obtained differed from the parent strains in colour of the conidia, growth factor requirements and amylase activity. Arginine deficient strains showed greater amylase activity.     

ENHANCED β-GALACTOSIDASE PRODUCTION OF Aspergillus oryzae MUTATED BY UV AND LiCl

In order to breed a high-yield β-galactosidase-producing strain, Aspergillus oryzae was used as the parent strain and mutagenized with ultraviolet (UV) and UV plus lithium chloride (LiCl), respectively. After being mutagenized by UV, the β-galactosidase activity of mutant UV-15-20 reached 114.08 U/mL, which revealed a 49.22% increase compared with the original strain. A mutant UV-LiCl-38 with high β-galactosidase activity (121.42U/mL) was obtained after compound mutagenesis of UV and LiCl; the β-galactosidase activity of this mutant was 58.82% higher than that of the parent strain. Subculture testing indicated that UV-15-20 and UV-LiCl-38 had good hereditary stability and may be ideal strains for the production of β-galactosidase. Additionally, it was demonstrated that compound mutagenesis with UV and LiCl is an effective mutation method for breeding industrially interesting strains.     

The photochemical reactions of bacterial sensory rhodopsin-I. Flash photolysis study in the one microsecond to eight second time window.

Halobacterium halobium Flx mutants are deficient in bacteriorhodopsin (bR) and halorhodopsin (hR). Such strains are phototactic and the light signal detectors are two additional retinal pigments, sensory rhodopsins I and II (sR-I and sR-II), which absorb maximally at 587 and 480 nm, respectively. A retinal-deficient Flx mutant, Flx5R, overproduces sR-I-opsin and does not show any photochemical activity other than that of sR-I after the pigment is regenerated by addition of all-trans retinal. Using native membrane vesicles from this strain, we have resolved a new photointermediate in the sR-I photocycle between the early bathointermediate S610 and the later intermediate S373. The new form, S560, resembles the L intermediate of bR in its position in the photoreaction cycle, its relatively low extinction, and its moderate blue shift. It forms with a half-time of approximately 90 microseconds at 21 degrees C, concomitant with the decay of S610. Its decay with a half-time of 270 microseconds parallels the appearance of S373. From a data set consisting of laser flash-induced absorbance changes (300 ns, 580-nm excitation) measured at 24 wavelengths from 340 to 720 nm in a time window spanning 1 microsecond to 8 s we have calculated the spectra of the photocycle intermediates assuming a unidirectional, unbranched reaction scheme.     

Pigments associated with the flagellum ofEuglena gracilis

The pigments associated with the flagellum of the phytoflagellateEuglena gracllis were characterized by HPLC. The pigment pattern of the wild-type strain was compared with a set of white mutants which did not display phototaxis and photoaccumulation in response to blue light. Flagella of the wild type contained FMN and FAD. Two mutants which lacked the stigma but retained a small paraxonemal body (PAB) contained less flavins. The whiteEuglena mutant FB, which retained a residual stigma and also a PAB, and the white phytoflagellateAstasia longa, a close relative ofEuglena, had normal amounts of flagellar flavins. Cells and flagella ofEuglena wild type contained an unldentified pterin-like pigment, called Pt₁₆, which was substantially reduced inAstasia and theEuglena mutants. A third pigment, designated P₅₂₈ with major absorption at 528 nm and fluorescence emission at 550 nm was present mainly in flagella. The association of the three pigment types with flagella and their respective alterations in the white strains indicates their possible role in photoreception. Dedicated to Pill-Soon Song on the occasion of his 60th birthday.     

Mutagenesis at the ad-3A and ad-3B loci in haploid UV-sensitive strains of Neurospora crassa. VI. Genetic characterization of ad-3 mutants provides evidence for qualitative differences in the spectrum of genetic alterations between wild-type and nucleotide excision-repair-deficient strains

Genetic characterization of ad-3B mutants induced in wild-type and UV-sensitive strains has revealed qualitative differences between the spectra of genetic alterations at the molecular level. Ad-3B mutants induced in the two nucleotide excision-repair-deficient strains upr-1 and uvs-2 (Worthy and Epler, 1973) had significantly lower frequencies of nonpolarized complementation patterns and higher frequencies of noncomplementing mutants than ad-3B mutants induced in the wild-type strain in samples induced by either UV, gamma-rays, 4NQO or MNNG. In these same samples ad-3B mutants induced in uvs-4, uvs-5 or uvs-6 did not differ significantly from those induced in the wild-type strain. After ICR-170 treatment, ad-3B mutants induced in the UV-sensitive strains did not differ significantly from those induced in wild-type. The comparisons in the present and previous studies demonstrate that the process of mutation-induction in the ad-3 region is under the control of other loci that not only alter mutant recovery quantitatively (de Serres, 1980; Schüpbach and de Serres, 1981; Inoue et al., 1981a, b) but also qualitatively. These data have important implications for comparative chemical mutagenesis, since the spectrum of genetic alterations produced by a given agent can be modified markedly as a result of defects in DNA repair.     

Induction of mutation in Azotobacter chroococcum MAL-201 for improvement of P(3HB) production

Azotobacter chroococcum MAL-201 (MTCC 3853), a poly-3-hydroxybutyric acid [P(3HB)] producing organism was subjected to mutagenesis by UV-irradiation and N'-methyl-N'-nitro-N'-nitrosoguanidine (MNNG). A sharp decline in survival percentage of treated cells both in UV (1.2% at 20 sec. exposure) and in MNNG ((0.26% at 30 microg/ml) suggest high degree of sensitivity of the isolate to these mutagens. A total of 124 mutant colonies were isolated from viable population based on their morphological features, antibiotic resistance and dependence on exogenous organic nitrogenous substances. Nature of mutants were confirmed by replica plating and growth on antibiotic and organic nitrogen supplemented Norris agar medium. Majority of mutants were devoid of exopolysaccharide, dependent on organic nitrogen and with weak P(3HB) content. The mutant strain, UC-220, a nitrogen-dependent, chloramphenicol-resistant mutant showed an enhancement of more than 10% (w/w) P(3HB) production compared to that of wild type strain when grown under identical conditions.     

Strain improvement of Aspergillus niger for enhanced lipase production

The enhancement of lipase production from Aspergillus niger was attempted by ultraviolet (UV) and nitrous acid mutagenesis, and the mutants were selected on media containing bile salts. Nitrous acid mutants exhibited increased efficiency for lipase production when compared with UV mutants in submerged fermentation. The hyperproducing UV and nitrous acid mutants were further subjected to a second step of mutagenesis to devise an economical and ecofriendly technique for lipase production by the effective use of hydrocarbons. One percent kerosene was found to be optimal for lipase production, and one of the mutant strains NAII exhibited 2.53 times more increased lipase activity than the parental strain did. This investigation indicates a possible role for the A. niger mutant strains in the biodegradation of oil-polluted environments for the development of ecofriendly technologies.     

Strain improvement of Aspergillus niger for the enhanced production of asperenone

The enhancement of production of asperenone (Fig. 1), an inhibitor of lipoxygenase and human platelet aggregation from Aspergillus niger CFTRI 1105, was achieved by UV and nitrous acid mutagenesis. Nitrous acid mutants exhibited increased inhibitor production when compared with UV irradiated mutants. I N 41 a first-generation nitrous acid mutant produced 5.1 fold increased asperenone over parent strain. Mutant II N 31 obtained by second-generation nitrous acid treatment produced 60.3 mg asperenone/g biomass, which was 131 fold increase when compared to first generated mutant I N 41 and 670 fold increase over the parent strain. This mutant was stable for several generations on production medium.     

The molecular evolution of avian ultraviolet- and violet-sensitive visual pigments

The shortwave-sensitive SWS1 class of vertebrate visual pigments range in lambda(max) from the violet (385-445 nm) to the ultraviolet (UV) (365-355 nm), with UV-sensitivity almost certainly ancestral. In birds, however, the UV-sensitive pigments present in a number of species have evolved secondarily from an avian violet-sensitive (VS) pigment. All avian VS pigments expressed in vitro to date encode Ser86 whereas Phe86 is present in all non-avian ultraviolet sensitive (UVS) pigments. In this paper, we show by site directed mutagenesis of avian VS pigments that Ser86 is required in an avian VS pigment to maintain violet-sensitivity and therefore underlies the evolution of avian VS pigments. The major mechanism for the evolution of avian UVS pigments from an ancestral avian VS pigment is undoubtedly a Ser90Cys substitution. However, Phe86, as found in the Blue-crowned trogon, will also short-wave shift the pigeon VS pigment into the UV whereas Ala86 and Cys86 which are also found in natural avian pigments do not generate short-wave shifts when substituted into the pigeon pigment. From available data on avian SWS1 pigments, it would appear that UVS pigments have evolved on at least 5 separate occasions and utilize 2 different mechanisms for the short-wave shift.     

应用基因组改组技术选育竹红菌甲素高产菌株

以紫外(UV)与亚硝基胍诱变的竹黄菌(Shiraia bambusicola)菌株NU12和UV4为出发菌株,60℃处理5 min、紫外(距离30 cm,30 W)照射90s进行双亲原生质体灭活,通过30％聚乙二醇PEG6000介导原生质体融合20 min.结合平板初筛和高效液相色谱( HPLC)分析进行复筛,通过3轮重组融合操作,筛选出6株高产竹红菌甲素的融合株.其中融合菌株FIII - 21的竹红菌甲素产量达到80.4 mg/L,比原始出发菌株提高了58.9％～167.1％,且遗传稳定,具有较高的医药及工业应用价值.