In vivo evolution of lactic acid hyper-tolerant Clostridium thermocellum

Lactic acid (LA) has several applications in the food, cosmetics and pharmaceutical industries, as well as in the production of biodegradable plastic polymers, namely polylactides. Industrial production of LA is essentially based on microbial fermentation. Recent reports have shown the potential of the cellulolytic bacterium Clostridium thermocellum for direct LA production from inexpensive lignocellulosic biomass. However, C. thermocellum is highly sensitive to acids and does not grow at pH \u3c 6.0. Improvement of LA tolerance of this microorganism is pivotal for its application in cost-efficient production of LA. In the present study, the LA tolerance of C. thermocellum strains LL345 (wild-type fermentation profile) and LL1111 (high LA yield) was increased by adaptive laboratory evolution. At large inoculum size (10 %), the maximum tolerated LA concentration of strain LL1111 was more than doubled, from 15 g/L to 35 g/L, while subcultures evolved from LL345 showed 50–85 % faster growth in medium containing 45 g/L LA. Gene mutations (pyruvate phosphate dikinase, histidine protein kinase/phosphorylase) possibly affecting carbohydrate and/or phosphate metabolism have been detected in most LA-adapted populations. Although improvement of LA tolerance may sometimes also enable higher LA production in microorganisms, C. thermocellum LA-adapted cultures showed a yield of LA, and generally of other organic acids, similar to or lower than parental strains. Based on its improved LA tolerance and LA titer similar to its parent strain (LL1111), mixed adapted culture LL1630 showed the highest performing phenotype and could serve as a framework for improving LA production by further metabolic engineering

Status of the High-Frequency Upgrade of the Sardinia Radio Telescope

The Sardinia Radio Telescope is going through a major upgrade aimed at observing the universe at up to 116 GHz. A budget of 18.700.000 E has been awarded to the Italian National Institute of Astrophysics to acquire new state-of-the-art receivers, back-end, and high-performance computing, to develop a sophisticated metrology system and to upgrade the infrastructure and laboratories. This contribution draws the status of the whole project at eight months from the end of the funding scheme planned for August 2022

The high-frequency upgrade of the Sardinia Radio Telescope

We present the status of the Sardinia Radio Telescope (SRT) and its forthcoming update planned in the next few years. The post-process scenario of the upgraded infrastructure will allow the national and international scientific community to use the SRT for the study of the Universe at high radio frequencies (up to 116 GHz), both in single dish and in interferometric mode. A telescope like SRT, operating at high frequencies, represents a unique resource for the scientific community. The telescope will be ideal for mapping quickly and with relatively high angular resolution extended radio emissions characterized by low surface brightness. It will also be essential for spectroscopic and polarimetric studies of both Galactic and extragalactic radio sources. With the use of the interferometric technique, SRT and the other Italian antennas (Medicina and Noto) will operate within the national and international radiotelescope network, allowing astronomers to obtain images of radio sources at very high angular resolution