Microalgae biorefinery: High value products perspectives.

Cyanobacteria are the ideal organisms for the production of a wide range of bioproducts as they can convert CO2 directly into the desired end product using solar energy. Unfortunately, the engineering of cyanobacteria to create efficient cell factories has been impaired by the cumbersome genetic tools that are currently available for these organisms; especially when trying to accumulate multiple modifications. We sought to construct an efficient and precise tool for generating numerous markerless modifications in cyanobacteria using CRISPR technology and the alternative nuclease, Cpf1. In this study we demonstrate rapid engineering of markerless knock-ins, knock-outs and point mutations in each of three model cyanobacteria; Synechococcus, Synechocystis and Anabaena. The markerless nature of cpf1 genome editing will allow for complex genome modification that was not possible with previously existing technology while facilitating the development of cyanobacteria as highly modified biofactories.

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Cpf1 Is A Versatile Tool for CRISPR Genome Editing Across Diverse Species of Cyanobacteria

The soluble B vitamins (B1, B7, and B12) have long been recognized as playing a central metabolic role in marine phytoplankton and bacteria; however, the importance of these organic external metabolites in marine ecology has been largely disregarded, as most research has focused on inorganic nutrients and trace metals. Using recently available genomic data combined with culture-based surveys of vitamin auxotrophy (i.e., vitamin requirements), we show that this auxotrophy is widespread in the marine environment and occurs in both autotrophs and heterotrophs residing in oligotrophic and eutrophic environments. Our analysis shows that vitamins originate from the activities of some bacteria and algae and that taxonomic changes observed in marine phytoplankton communities could be the result of their specific vitamin requirements and/or vitamin availability. Dissolved vitamin concentration measurements show that large areas of the world ocean are devoid of B vitamins, suggesting that vitamin limitation could b...

The Role of B Vitamins in Marine Biogeochemistry

http://staff.ustc.edu.cn/~fhuang/publications/2015/201509.pdf

Vanadium: Global (bio)geochemistry

Probiotic application for sustainable aquaculture

Vanadium speciation and cycling in coastal waters

Axenic cultures of the N2-fixing marine cyanobacterium Crocosphaera watsonii exhibit very high B12 excretion rates (up to 40 times higher per cell), compared to the smaller non-N2-fixing strain of marine Synechococcus. The effect of N availability on vitamin synthesis is also evident in the non-diazotrophic strain, as they release five times more B12 under N-replete conditions relative to N-limiting conditions, although this value is still an order of magnitude smaller than the amount produced by the diazotroph. The cyanobacterial contribution to the oceanic B12 supply may be ~ 50 times higher than the contribution of heterotrophic bacteria. Oceanic cyanobacteria do not compete for exogenous B12 with other prokaryotes and eukaryotes, but instead are obligate producers, thereby defining a unique dual ecological role for N2-fixing cyanobacteria in the oligotrophic ocean. They provide both a source of “new” bioavailable nitrogen and the B12 needed to support the growth of larger auxotrophic eukaryotic phytoplankton important for the biological carbon pump.

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Sergio A. Sañudo Wilhelmy

Papers

Vanadium speciation and cycling in coastal waters

Vitamin B12 excretion by cultures of the marine cyanobacteria Crocosphaera and Synechococcus