Integrated Omics Strategy Reveals Cyclic Lipopeptides Empedopeptins from Massilia sp. YMA4 and Their Biosynthetic Pathway

Empedopeptins—eight amino acid cyclic lipopeptides—are calcium-dependent antibiotics that act against Gram-positive bacteria such as Staphylococcus aureus by inhibiting cell wall biosynthesis. However, to date, the biosynthetic mechanism of the empedopeptins has not been well identified. Through comparative genomics and metabolomics analysis, we identified empedopeptin and its new analogs from a marine bacterium, Massilia sp. YMA4. We then unveiled the empedopeptin biosynthetic gene cluster. The core nonribosomal peptide gene null-mutant strains (ΔempC, ΔempD, and ΔempE) could not produce empedopeptin, while dioxygenase gene null-mutant strains (ΔempA and ΔempB) produced several unique empedopeptin analogs. However, the antibiotic activity of ΔempA and ΔempB was significantly reduced compared with the wild-type, demonstrating that the hydroxylated amino acid residues of empedopeptin and its analogs are important to their antibiotic activity. Furthermore, we found seven bacterial strains that could produce empedopeptin-like cyclic lipopeptides using a genome mining approach. In summary, this study demonstrated that an integrated omics strategy can facilitate the discovery of potential bioactive metabolites from microbial sources without further isolation and purification.     

Effect of micronutrients on B‐N‐Oxalyl l‐α, β‐diamino propionic acid level and its biosynthesis in Lathyrus Sativus

The detoxification of L. sativus grains by spraying of 0.5 ppm cobalt (nitrate) and 20 ppm molybdehum (ammonium molybdate) salts at the maximun flowering stage ‐ a suggestion based on preliminary findings ‐ has been confirmed in this investigation. Regulatory mechanisms of these micronutrients at the enzymatic level were also studied. On the basis of these observations, the involvement of a hitherto unknown biosynthetic pathway of BOAA cannot be ruled out.     

Effect of Baking Process on Added Folic Acid and Endogenous Folates Stability in Wheat and Rye Breads

In Poland bread as a staple food both made from wheat and rye flour can be a potential product for future fortification with folic acid. The objective of the study was to examine the effect of fermentation and baking on added folic acid and some endogenous folates stability during breadmaking of rye and wheat breads. Breads were produced using the formulation containing enriched flour with 0.2 mg folic acid/100 g product, baker’s yeast and additionally ascorbic acid for wheat bread and lactic acid for rye bread. Folates were extracted with Hepes/Ches buffer (pH = 7.85) followed by destruction of matrix by amylase and protease and deconjugation with rat serum conjugase. Affinity chromatography (FBP bovine milk) was used to purify and concentrate samples. The folates were separated by HPLC with C18 column and with a combination of fluorescence and UV detection. For both rye and wheat breads there was a decrease of folic acid from flour to bread stage. The total losses depend on baking process and ranged from 12 to 21%. Some changes in the level of different native folate forms during the stage of baking process were also observed.     

Radiation effect on ascorbic acid and riboflavin biosynthesis in germinating soybean

The influence of irradiation on biosynthesis of ascorbic acid and riboflavin in germinating soybean seeds in tap and distilled water at ambient (25–35°C) conditions was investigated. Ascorbic acid was not detectable in the original seeds and the initial level of riboflavin was 3.3 g/g. The rate of synthesis of these vitamins increased with increasing germination time up to 72–96hr followed by a decreasing pattern depending upon the treatment. The effect of irradiation and germination on the synthesis of these vitamins was statistically significant (P<0.01). Maximum amounts of ascrobic acid 16.2 and 15.0 mg/ 100 g (fresh weight basis) were found in the 0.10 kGy sample after 72 hr of germination in tap and distilled water, respectively. However, a radiation dose of 0.20 kGy resulted in the development of maximum values of riboflavin, 30.0 and 27.0 g/g (dry weight basis) on germination in tap and distilled water respectively.     

东方百合L_sCCR1基因的克隆及表达分析

百合茎秆的挺度直接关系到百合花采收后的货架寿命等重要商品性状,而这些商品性状与植物茎秆中的木质素的含量高低有关.本文应用RLM-RACE技术,从东方百合索蚌植株中克隆了木质素合成相关基因一肉桂酰辅酶A还原酶,定名为LsCCR1.该基因cDNA全长为1 499 bp,包括完整的阅读框,编码388个氨基酸.多重比对分析发现百合LsCCR1基因与其他植物上已经发现的CCR基因同源性多介于55%～66%之间.利用半定量PCR检测LsCCR1基因在百合不同组织中的表达差异,结果显示LsCCR1基因主要在百合的茎秆中表达,根部次之,叶片、鳞茎及花蕾中表达量较少,其表达模式与拟南芥、桉树及大麦中CCR基因的表达模式类似.     

Precursor-Directed Biosynthesis Mediated Amplification of Minor Aza Phenylpropanoid Piperazines in an Australian Marine Fish-Gut-Derived Fungus,Chrysosporium sp. CMB-F214

Chemical analysis of an M1 agar plate cultivation of a marine fish-gut-derived fungus, Chrysosporium sp. CMB-F214, revealed the known chrysosporazines A–D (11–14) in addition to a suite of very minor aza analogues 1–6. A microbioreactor (MATRIX) cultivation profiling analysis failed to deliver cultivation conditions that significantly improved the yields of 1–6; however, it did reveal that M2 agar cultivation produced the new natural product 15. A precursor-directed biosynthesis strategy adopting supplementation of a CMB-F214 M1 solid agar culture with sodium nicotinate enhanced production of otherwise inaccessible azachrysposorazines A1 (1), A2 (2), B1 (3), C1 (4), C2 (5) and D1 (6), in addition to four new chrysosporazines; chrysosporazines N–P (7–9) and spirochrysosporazine A (10). Structures inclusive of absolute configurations were assigned to 1–15 based on detailed spectroscopic and chemical analyses, and biosynthetic considerations. Non-cytotoxic to human carcinoma cells, azachrysosporazies 1–5 were capable of reversing doxorubicin resistance in P-glycoprotein (P-gp)-overexpressing human colon carcinoma cells (SW620 Ad300), with optimum activity exhibited by the C-2′ substituted analogues 3–5.     

Enantiomeric compositions and biosynthesis ofWikstroemia sikokiana lignans

Thymelaeaceae plants produce dextrorotatory dibenzylbutyrolactone lignans, which are opposite enantiomers to the lignans isolated from other plants (e.g.,Forsythia spp.). In our previous paper, (–)-pinoresinol (74% enantiomer excess), (+)-matairesinol (optically pure), and (+)-wikstromol (optically pure) were isolated fromWikstroemia sikokiana (Thymelaeaceae). In the present investigation, a survey of lignans and the determination of their enantiomeric compositions were continued. Four lignans, (–)-lariciresinol, (–)-secoisolariciresinol, (+)-kusunokinin, and (+)-methyltrachelogenin, were isolated from MeOH extracts ofW. sikokiana stem. To our knowledge, we have isolated (+)-methyltrachelogenin from plants for the first time. Chiral high-performance liquid chromatographic analysis showed that (+)-kusunokinin and (+)-methyltrachelogenin were optically pure, whereas (–)-lariciresinol and (–)-secoisolariciresinol were not (39% and 45% enantiomer excess, respectively). Feeding experiments with deuterium-labeled substrates demonstrated conversion of coniferyl alcohol to the lignans and interconversion of lignans. These reaction sequences are similar to the sequence catalyzed byForsythia enzymes. However, predominant enantiomers of the lignans, except for secoisolariciresinol isolated fromW. sikokiana, have absolute configurations opposite to those of the corresponding lignans isolated fromForsythia spp. Based on the results of the isolation and the feeding experiments, several differences betweenW. sikokiana andForsythia spp. are pointed out regarding stereochemical mechanisms for lignan biosynthesis.Parts of this report were presented at the 46th annual meeting of the Japan Wood Research Society, Kumamoto, April 1996; and the 47th annual meeting of the Japan Wood Research Society, Kochi, April 1997     

Effects of temperature, irradiance, salinity and inorganic nitrogen concentration on coral zooxanthellae in culture

SUMMARY: Effects of temperature, irradiation, salinity and inorganic nitrogen concentration on two cultured strains of zooxanthellae isolated from the corals Pocillopora damicornis (strain P) and Montipora verrucosa (strain M) were studied. Each strain showed different growth responses in terms of temperature and light intensity. A maximum growth rate of strain P, 1.2 per day, was observed at 32°C under all light intensities examined (5–40 μEm⁻²s⁻¹). However, its photosystem 2 activity (FRI) was higher at 28°C than at 32°C under most light intensities. In contrast, the growth rate of strain M was affected more by light intensity and was almost invariably affected at all temperatures examined (24–36°C). Both algal strains had a comparable growth rate and FRI at salinities from 20 to 35 PSU under moderate temperature and irradiant conditions. High temperature and low irradiation reduced the algal tolerance against low salinity. The gross photosynthesis per cell was not affected by the ammonium enrichment more than 5 μM per day although the cellular chlorophyll a content and cell density increased in proportion with the ammonium enrichment up to 20 μM per day. A potential response of zooxanthellae to the multiple environmental stresses was shown from these results.     

海参皂苷的研究现状

海洋中蕴涵着丰富的天然资源,海参作为一种食品和药材,具有很高的保健功能和药用价值。海参皂苷是海参体内的一种次生代谢产物,具有广泛的生理药理活性,因此潜藏了极大的应用价值。本文就近年来国内外关于海参皂苷性质的研究状况做一些简要的概述,为进一步研究海参皂苷提供较为详尽的参考资料。     

Secondary Metabolites and Biosynthetic Gene Clusters Analysis of Deep-Sea Hydrothermal Vent-Derived Streptomyces sp. SCSIO ZS0520

Streptomyces sp. SCSIO ZS0520 is a deep-sea hydrothermal vent-derived actinomycete. Our previous metabolism investigation showed that Streptomyces sp. SCSIO ZS0520 is a producer of cytotoxic actinopyrones. Here, another four types of secondary metabolites were identified, including six salinomycin isomers (2–7), the macrolide elaiophylin (8), the triterpene N-acetyl-aminobacteriohopanetriol (9), and the pyrone minipyrone (10). Among them, compounds 2–6 and 10 are new compounds. To understand the biosynthetic pathway of these compounds, a bioinformatic analysis of the whole genome was carried out, which identified 34 secondary metabolite biosynthetic gene clusters. Next, the biosynthetic pathways responsive to four types of products were deduced on the basis of gene function predictions and structure information. Taken together, these findings prove the metabolite potential of ZS0520 and lay the foundations to solve the remaining biosynthetic issues in four types of marine natural products.