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Green macroalgae have gained attention as promising renewable sources for biorefining. Despite the wide potential availability of green macroalgae, their utilization has been limited to ethanol production, hindering their further application. In this study, we report that a bacterium, Halomonas sp. strain BL6 (isolated from a mangrove forest in Bach Long, Nam Dinh Province, Vietnam), produces pyruvate from a saccharified solution of the green seaweed Ulva reticulata and secretes it into the medium. Pyruvate, an important α-oxocarboxylic acid, plays a central role in energy and carbon metabolism in living organisms and is used mainly for the synthesis of various chemicals and polymers or as an ingredient or additive in food, cosmetics, and pharmaceuticals. To investigate the possibility of using U. reticulata from the seashore of Vietnam as biomass feedstock, the chemical composition and saccharification yield of this seaweed were studied. Dry biomass of U. reticulata was found to contain 65.5% carbohydrate, 10.3% protein, 1.8% lipid, and 10.6% ash. Reducing sugar content reached 608.79 mg g−1 of biomass after pretreatment with diluted acid and 24 h of incubation with 50 IU g−1 Viscozyme L. The resulting sugars were fermented by Halomonas sp. strain BL6 to produce pyruvate, and the maximal pyruvate concentration reached 55.23 g L−1 after 72 h of cultivation. This study is the first to report the production of valuable compounds other than bioethanol products, such as pyruvate, from U. reticulata hydrolysate by a Halomonas strain.

Nowadays, nanotechnology is one of the most potential tools in the modern agriculture to improve productivity, adaptation to climate change and sustainable development. In this study, the effect of nanoscale zerovalent cobalt (NZVC) on the growth, photosynthetic parameters expressed by Fo (initial fluorescence), Fm (maximal fluorescence), Fv/Fm (maximal photochemical efficiency), ΦPSII (effective quantum yield of photosystem II), ETR (photosynthetic electron transport rate), Pn (net photosynthetic rate) and content of chlorophyll a and b at different stages in soybean leaves were investigated. The NZVC made from Vietnam and USA with different concentrations (0, 0.17 and 16.7 mg/kg seed) were used. It was found that when soybean seeds were treated with NZVC, the growth indices (such as the plant height, dry weights of stems and leaves and leaf area), photosynthetic parameters and chlorophyll a and b content were increased obviously compared with that of the control. These values had tended to gradually increase and reach maximum at fifth (V5) trifoliate stage, whereas they were significantly decreased at begin at flowering (R1) stage. The real productivity of the experimental formulas exceeded the control (5%), while the quality of grain was significant different among the plots. The zerovalent cobalt nanoparticle from Vietnam exhibited similar efficiency compared to those that came from USA. Our results indicated that photosynthesis was positively affected by NZVC, leading to the improved growth of soybean and therefore to improved productivity as a whole.