Browsing by Autor "Magnus Karlsson"

Now showing 1 - 3 of 3

Brewery spent yeast medium for Serratia sp. bio-beads improves Chenopodium quinoa Willd. growth in the Northern Altiplano of Bolivia
(Oxford University Press, 2025) Ximena Ramirez; V. S. Gonzales; Rogelio Maydana; Mukesh Dubey; Dan Funck Jensen; Cristhian Carrasco; Magnus Karlsson; Carla Crespo
Quinoa (Chenopodium quinoa Willd.) is a climate-resilient Andean crop with high nutritional value and strategic importance for food security in high-altitude regions. However, its productivity in low-input farming systems remains limited. This study developed scalable strategies for propagation and formulation of a Serratia sp. strain as a biofertilizer, using brewery spent yeast (BSY) as growth substrate. Microwave-assisted extraction (MAE) at 1200 W for 15 min significantly (P ≤ 0.05) enhanced soluble protein release from BSY, and MAE-treated media with a C:N ratio of 24:1 supported optimal bacterial growth. Carrageenan-based bio-bead formulations produced at 40°C with 96 g L⁻¹ carrageenan yielded the highest bacterial viability and moisture retention. In a field trial in the Bolivian Altiplano, bio-beads containing Serratia sp. applied at branching stage increased quinoa yield by up to 3.4-fold (P ≤ 0.01) compared with the control. The formulation control also substantially improved yield (2.2-fold), indicating that both the carrier matrix and bacterial inoculation contributed to growth enhancement. These findings demonstrate the potential of biofertilizer technologies based on agri-food by-product valorization to improve crop performance under extreme and resource-limited agricultural conditions.
Diversity of Trichoderma in the unexplored Bolivian Amazon region and their potential for coffee diseases control
(Oxford University Press, 2025) Marisel M Mamani; Lilia Catacora; Nélida Nina; Wendy Daniela Tola Alarcon; Feng M Cai; Jesper Rydèn; Irina S. Druzhinina; Dan Funck Jensen; Carla Crespo; Magnus Karlsson
Trichoderma fungi are colonizers of plant substrates and rhizosphere and are valued for their antagonism against phytopathogens and ability to promote plant health. We investigated Trichoderma diversity in coffee-growing soils in Caranavi region of Yungas-La Paz, Bolivia, where high humidity and fungal diseases threaten yield, and evaluated their potential as biocontrol agents against coffee pathogens. A total of 440 Trichoderma were isolated from coffee rhizosphere, fallow lands, and forest ecosystems across an altitudinal gradient in Caranavi. DNA barcode analyses using ITS, rpb2, and tef1 loci identified only four species. However, 47 taxa comprising 344 isolates were ambiguous, and 41 isolates were previously unrecognised species. The diversity of Trichoderma spp. was significantly affected by ecosystem type and altitude, with more species isolated from coffee rhizosphere than fallow lands and forest ecosystems, and from lower altitudes than higher ones. Evaluation of 100 isolates against a native coffee wilt pathogen Fusarium oxysporum identified 70 potent antagonists, with 30 achieving 90-100% disease control. This is the first comprehensive study of Trichoderma diversity in Yungas, identifying indigenous Trichoderma for biocontrol applications against coffee diseases. It also emphasizes the need to refine the Trichoderma species concept and improve the taxonomic resolution within the genus.
Rhizosphere bacteria from the Bolivian highlands improve drought tolerance in quinoa (Chenopodium quinoa Willd.)
(Oxford University Press, 2024) V. S. Gonzales; María Huallpan; Ximena Vargas-Ramírez; Yessica San Miguel; Mukesh Dubey; Dan Funck Jensen; Magnus Karlsson; Carla Crespo
Microorganisms from the arid Bolivian altiplano constitute a potential biological source of bioinoculants to improve quinoa productivity and provide sustainable mitigation of climate change effects.