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1. High impact of bacterial predation on cyanobacteria in soil biocrusts

   https://doi.org/10.1038/s41467-022-32427-5  

   Bethany, Julie; Johnson, Shannon_Lynn; Garcia-Pichel, Ferran (August 2022, Nature Communications)

   Abstract Diverse bacteria lead a life as pathogens or predators of other bacteria in many environments. However, their impact on emerging ecological processes in natural settings remains to be assessed. Here we describe a novel type of obligate, intracellular predatory bacterium of widespread distribution that preys on soil cyanobacteria in biocrusts. The predator,CandidatusCyanoraptor togatus, causes localized, cm-sized epidemics that are visible to the naked eye, obliterates cyanobacterial net primary productivity, and severely impacts crucial biocrust properties like nitrogen cycling, dust trapping and moisture retention. The combined effects of high localized morbidity and areal incidence result in decreases approaching 10% of biocrust productivity at the ecosystem scale. Our findings show that bacterial predation can be an important loss factor shaping not only the structure but also the function of microbial communities. 

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2. Phenotypically complex living materials containing engineered cyanobacteria

   https://doi.org/10.1038/s41467-023-40265-2  

   Datta, Debika; Weiss, Elliot L.; Wangpraseurt, Daniel; Hild, Erica; Chen, Shaochen; Golden, James W.; Golden, Susan S.; Pokorski, Jonathan K. (August 2023, Nature Communications)

   Abstract The field of engineered living materials lies at the intersection of materials science and synthetic biology with the aim of developing materials that can sense and respond to the environment. In this study, we use 3D printing to fabricate a cyanobacterial biocomposite material capable of producing multiple functional outputs in response to an external chemical stimulus and demonstrate the advantages of utilizing additive manufacturing techniques in controlling the shape of the fabricated photosynthetic material. As an initial proof-of-concept, a synthetic riboswitch is used to regulate the expression of a yellow fluorescent protein reporter inSynechococcus elongatusPCC 7942 within a hydrogel matrix. Subsequently, a strain ofS. elongatusis engineered to produce an oxidative laccase enzyme; when printed within a hydrogel matrix the responsive biomaterial can decolorize a common textile dye pollutant, indigo carmine, potentially serving as a tool in environmental bioremediation. Finally, cells are engineered for inducible cell death to eliminate their presence once their activity is no longer required, which is an important function for biocontainment and minimizing environmental impact. By integrating genetically engineered stimuli-responsive cyanobacteria in volumetric 3D-printed designs, we demonstrate programmable photosynthetic biocomposite materials capable of producing functional outputs including, but not limited to, bioremediation. 

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3. Mixotrophic metabolism by natural communities of unicellular cyanobacteria in the western tropical South Pacific Ocean: Mixotrophy in natural marine cyanobacteria

   https://doi.org/10.1111/1462-2920.14111  

   Duhamel, Solange; Van Wambeke, France; Lefevre, Dominique; Benavides, Mar; Bonnet, Sophie (August 2018, Environmental Microbiology)
4. Discovery of Novel Tyrosinase Inhibitors From Marine Cyanobacteria

   https://doi.org/10.3389/fmicb.2022.912621  

   He, Yifan; Suyama, Takashi L.; Kim, Hyunwoo; Glukhov, Evgenia; Gerwick, William H. (July 2022, Frontiers in Microbiology)

   Tyrosinase, an important oxidase involved in the primary immune response in humans, can sometimes become problematic as it can catalyze undesirable oxidation reactions. Therefore, for decades there has been a strong pharmaceutical interest in the discovery of novel inhibitors of this enzyme. Recent studies have also indicated that tyrosinase inhibitors can potentially be used in the treatment of melanoma cancer. Over the years, many new tyrosinase inhibitors have been discovered from various natural sources; however, marine natural products (MNPs) have contributed only a small number of promising candidates. Therefore, in this study we focused on the discovery of new MNP tyrosinase inhibitors of marine cyanobacterial and algal origins. A colorimetric tyrosinase inhibitory assay was used to screen over 4,500 marine extracts against mushroom tyrosinase ( A. bisporus ). Our results revealed that scytonemin monomer (ScyM), a pure compound from our compound library and also the monomeric last-step precursor in the biosynthesis of the well-known cyanobacterial sunscreen pigment “scytonemin,” consistently showed the highest tyrosinase inhibitory score. Determination of the half maximal inhibitory concentration (IC 50 ) further indicated that ScyM is more potent than the commonly used commercial inhibitor standard “kojic acid” (KA; IC 50 of ScyM: 4.90 μM vs. IC 50 of KA: 11.31 μM). After a scaled-up chemical synthesis of ScyM as well as its O -methyl analog (ScyM-OMe), we conducted a series of follow-up studies on their structures, inhibitory properties, and mode of inhibition. Our results supported ScyM as the second case ever of a novel tyrosinase inhibitory compound based on a marine cyanobacterial natural product. The excellent in vitro performance of ScyM makes it a promising candidate for applications such as a skin-whitening agent or an adjuvant therapy for melanoma cancer treatment. 

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5. Thermodynamics contributes to high limonene productivity in cyanobacteria

   https://doi.org/10.1016/j.mec.2022.e00193  

   Shinde, Shrameeta; Singapuri, Sonali; Jiang, Zhenxiong; Long, Bin; Wilcox, Danielle; Klatt, Camille; Jones, J. Andrew; Yuan, Joshua S.; Wang, Xin (June 2022, Metabolic Engineering Communications)