Carotenoids are organic lipophilic yellow to orange and reddish pigments of terpenoid nature that are usually composed of eight isoprene units. This group of secondary metabolites includes carotenes and xanthophylls, which can be naturally obtained from photosynthetic organisms, some fungi, and bacteria. One of the microorganisms able to synthesise carotenoids is the heterobasidiomycetous yeast Xanthophyllomyces dendrorhous, which represents the teleomorphic state of Phaffia rhodozyma, and is mainly used for the production of the xanthophyll astaxanthin. Upgraded knowledge on the biosynthetic pathway of the main carotenoids synthesised by X. dendrorhous, the biotechnology-based improvement of astaxanthin production, as well as the current omics approaches available in this yeast are reviewed in depth.

Proteomics is a powerful tool to understand the molecular mechanisms causing the production of high penicillin titers by industrial strains of the filamentous fungus Penicillium chrysogenum as the result of strain improvement programs. Penicillin biosynthesis is an excellent model system for many other bioactive microbial metabolites. The recent publication of the P. chrysogenum genome has established the basis to understand the molecular processes underlying penicillin overproduction. We report here the proteome reference map of P. chrysogenum Wisconsin 54-1255 (the genome project reference strain) together with an in-depth study of the changes produced in three different strains of this filamentous fungus during industrial strain improvement. Two-dimensional gel electrophoresis, peptide mass fingerprinting, and tandem mass spectrometry were used for protein identification. Around 1000 spots were visualized by “blue silver” colloidal Coomassie staining in a non-linear pI range from 3 to 10 with high resolution, which allowed the identification of 950 proteins (549 different proteins and isoforms). Comparison among the cytosolic proteomes of the wild-type NRRL 1951, Wisconsin 54-1255 (an improved, moderate penicillin producer), and AS-P-78 (a penicillin high producer) strains indicated that global metabolic reorganizations occurred during the strain improvement program. The main changes observed in the high producer strains were increases of cysteine biosynthesis (a penicillin precursor), enzymes of the pentose phosphate pathway, and stress response proteins together with a reduction in virulence and in the biosynthesis of other secondary metabolites different from penicillin (pigments and isoflavonoids). In the wild-type strain, we identified enzymes to utilize cellulose, sorbitol, and other carbon sources that have been lost in the high penicillin producer strains. Changes in the levels of a few specific proteins correlated well with the improved penicillin biosynthesis in the high producer strains. These results provide useful information to improve the production of many other bioactive secondary metabolites.

The effect of climate change on flora and fauna has been widely discussed for years. However, its consequences on microorganisms are generally poorly considered. The main effect of climate change on microbiota is related to biodiversity changes in different regions of the planet, mainly due to variations in temperature. These alterations are resulting in a worldwide (re)distribution of pathogens, which was not considered a few years ago. They mainly affect different food chain sectors (such as agriculture, livestock and fishing), as well as human health. Hence, the spread of numerous animal and plant pathogens has been observed in recent years from south to north (especially in America, Europe and Asia), leading to the spread of numerous plant and animal diseases, which results in economic and ecological losses. In addition, global warming that accompanies climate change could also be related to emerging antibiotic resistance. However, the mitigation of climate change goes hand in hand with microorganisms, which can help us through different natural and industrial processes. Thus, this manuscript presents the direct and indirect effects of climate change on microorganisms described up to date and how they act on this worldwide phenomenon.

Nowadays, legal regulations and social environmental concerns are converging towards the promotion of more sustainable agriculture based on organic compounds and soil preservation. These trends are fuelling the growth of the biofertilizers, which are beneficial preparations containing microorganisms able to enhance a plant’s ability to uptake essential nutrients. Their production and commercialization encompass a multitude of critical steps deeply reviewed in this manuscript through an exhaustive overview of the key stages, such as microorganism selection, new environmental sources, upscaling to field trials, encapsulation, current application systems and regulatory considerations. However, although the economical expectations are promising, several methodological, environmental, and legal concerns are undermining their advancement. The redefinition of international legal frameworks, their enhancement based on trending technologies, and the fostering of multidisciplinary collaboration across sectors are key players to promote biofertilizers as eco-friendly and cost-effective alternatives to chemical fertilizers.

Carotenoids are the pigments present in plants, animals, and microorganisms which are responsible for a broad variety of colors found in nature. Their capacity as antioxidants mainly established their marketable success as health, food, and feed supplements, and cosmetics components. Currently, chemical synthesis dominates the worldwide market; however, due to the high biological value of natural carotenoids, the production scheme is moving towards microbial production as a profitable alternative.