Genome Insight and Description of Carotenoids-producing Croceicoccus Gelatinilyticus Sp. Nov., Isolated From the Tidal Flat Sediment

A novel Gram-staining-negative and short-rod-shaped bacterial strain designated as 1NDH52T was isolated from tidal flat sediments and characterized by using a polyphasic taxonomic approach. The predominant cellular fatty acids of strain 1NDH52T were summed feature 8 (C18:1 ω7c and/or C18:1 ω6c) and C14:0 2-OH; the major polar lipids were diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol and sphingoglycolipid; the major respiratory quinones were Q-10 and Q-9. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain 1NDH52T belonged to the genus Croceicoccus with high similarities to the close type strains Croceicoccus pelagius Ery9T, Croceicoccus sediminis S2-4-2T and Croceicoccus bisphenolivorans H4T. Phylogenomic analysis indicated that strain 1NDH52T formed an independent branch distinct from the known type strains of this genus. Digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values between strain 1NDH52T and the three type strains above were well below thresholds of 70% DDH and 95-96% ANI for species definition, implying that strain 1NDH52T should represent a novel genospecies. The genomic DNA G + C content was 62.6%. The carotenoids production of the novel strain was determined by the detection of the pigment absorption spectrum and the identification of the complete biosynthetic gene cluster in its genome. Based on the phenotypic and genotypic characteristics, strain 1NDH52T is concluded to represent a novel species of the genus Croceicoccus, for which the name Croceicoccus gelatinilyticus sp. nov., is proposed. The type strain of the species is 1NDH52T (= GDMCC 1.2381T = KCTC 82668T). The description of the genus Croceicoccus has also been emended.

Coloration of Flowers by Flavonoids and Consequences of pH Dependent Absorption

Flavonoid pigments are key determinants of flower colors. As absorption spectra of flavonoids are known to be severely pH-dependent, cellular pH will play a crucial role in flower coloration. The flavonoids are concentrated in the vacuoles of the flowers’ epidermal cells, and thus the pigments’ absorption spectra are modulated by the vacuolar pH. Here we study the pH dependence of flavonoid absorption spectra in extracts from flowers of two poppy species Papaver dubium (red) and Meconopsis cambrica (orange), and a white and red Mandevilla sanderi variety. In the red poppy and Mandevilla flowers, absorption spectra of the cyanidin- and pelargonidin-based anthocyanins peak in the blue-green-wavelength range at low pH, but exhibit a distinct bathochromic shift at higher pH. This shift to longer wavelengths is not found for the blue-absorbing nudicaulin derivatives of M. cambrica, which have a similar absorption spectrum at low and high pH. The pH-dependent absorption changes of the white M. sanderi’s flavonoid remained restricted to the UV. An analysis of the spectra with logistic functions suggests that the pH-dependent characteristics of the basic states of flavonols and anthocyanins are related. The implications of tuning of pH and pigment absorption spectra for studies on flower color evolution are discussed.

Exploring the Optical Properties of Leaf Photosynthetic and Photo-Protective Pigments In Vivo Based on the Separation of Spectral Overlapping

The in vivo features of the absorption of leaf photosynthetic and photo-protective pigments are closely linked to the leaf spectrum in the 400–800 nm regions. However, this information is difficult to obtain because the overlapping leaf pigments can mask the contribution of individual pigments to the leaf spectrum. Here, to limit the masking phenomenon between these pigments, the separation technology for leaf spectral overlapping was employed in the PROSPECT model with the ZJU dataset. The main results of this study include the following aspects: (1) the absorption coefficients of separated chlorophyll a and b, carotenoids and anthocyanins in the leaf in vivo display the physical principles of forming an absorption spectrum similar to those in an organic solution; (2) the differences in the position of each absorption peak of pigments between the leaf in vivo and in an organic solution can be described by a spectral displacement parameter; and (3) the overlapping characteristics between the separated pigments in the leaf in vivo are clearly drawn by a range of absorption feature (RAF) parameter. Moreover, the absorption coefficients of the separated pigments were successfully applied in leaf spectral modeling and pigment retrieval. The results show that the separated multiple pigment absorption coefficients from the leaf spectrum in vivo are effective and provide a framework for future refinements in describing leaf optical properties.