Chlorella and Stichococcus are morphologically simple airborne microalgae, omnipresent in terrestrial and aquatic habitats. The minute cell size and resistance against environmental stress facilitate their long-distance dispersal. However, the actual distribution of Chlorella- and Stichococcus-like species has so far been inferred only from ambiguous morphology-based evidence. Here we contribute a phylogenetic analysis of an expanded SSU and ITS2 rDNA sequence dataset representing Chlorella- and Stichococcus-like species from terrestrial habitats of polar, temperate and tropical regions. We aim to uncover biogeographical patterns at low taxonomic levels. We found that psychrotolerant strains of Chlorella and Stichococcus are closely related with strains originating from the temperate zone. Species closely related to Chlorella vulgaris and Muriella terrestris, and recovered from extreme terrestrial environments of polar regions and hot deserts, are particularly widespread. Stichococcus strains from the temperate zone, with their closest relatives in the tropics, differ from strains with the closest relatives being from the polar regions. Our data suggest that terrestrial Chlorella and Stichococcus might be capable of intercontinental dispersal; however, their actual distributions exhibit biogeographical patterns.

• MeSH
• biofilmy klasifikace   MeSH
• Chlorella vulgaris klasifikace   genetika   růst a vývoj   MeSH
• Chlorophyta klasifikace   genetika   růst a vývoj   MeSH
• ekosystém MeSH
• fylogeneze MeSH
• fylogeografie MeSH
• mezerníky ribozomální DNA genetika   MeSH
• studené klima * MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Antarktida MeSH
• Arktida MeSH

Agriculture is at the pivot point between anthroposphere, biosphere, and atmosphere. Innovative solutions are needed to reduce agricultural emissions and improve sustainability. Microalgae animal feed could be such a solution. This study aimed to evaluate the effects of 10 freshwater microalgae: Auxenochlorella protothecoides, Chlamydomonas pulvinate, Chlorella luteoviridis, Chlorella variabilis, Euglena mutabilis, Parachlorella kessleri, Stichococcus bacillaris, Tetradesmus acuminatus, Tetradesmus obliquus, and Tetraselmis gracilis, on ruminal methane (CH4) production, nutrient digestibility, and rumen fermentation using the in vitro Hohenheim gas test. The microalgae were cultured in a carbon dioxide (CO2) incubator at 2% CO2, at the optimal conditions for each strain. The highest producers were P. kessleri and T. obliquus, with a biomass concentration of 0.69 and 0.73 g/L·d, respectively. Their PUFA contents ranged from 33.2% to 69.1% of total fatty acids. Microalgae were tested at a 15% replacement in a control basal diet of 40.0% DM grass silage, 40.0% maize silage, 15% hay, and 5% concentrate. Data were analyzed using a mixed model in R. Ruminal CH4 production was reduced by 15.4%, 17.4%, and 16.4% in diets containing A. protothecoides, C. luteoviridis, and P. kessleri, respectively, compared with the control diet. Similarly, these diets reduced in vitro organic matter digestibility by 3.5%, 5.2%, and 5.4%, respectively. However, only A. protothecoides reduced CH4/CO2 ratio by 3.5% compared with the control diet. Propionate molar proportion was decreased by 2.4, 3.0, 2.5, and 2.5 percentage points for diets containing Ch. pulvinate, E. mutabilis, P. kessleri, and T. obliquus, respectively. Marginal effects of dietary variables were analyzed using the generalized additive model framework, revealing a negative relationship between dietary PUFA, sulfur content, and CH4 production, and a negative relationship between dietary PUFA and CH4/CO2 ratio. Incorporating high-PUFA microalgae in ruminant diets shows potential for reducing enteric CH4 emissions, warranting further investigation.

• MeSH
• bachor * metabolismus   MeSH
• dieta veterinární   MeSH
• fermentace MeSH
• krmivo pro zvířata MeSH
• methan * metabolismus   MeSH
• mikrořasy * metabolismus   MeSH
• siláž MeSH
• skot MeSH
• sladká voda MeSH
• trávení MeSH
• zvířata MeSH
• Check Tag
• skot MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH