Examinando por Autor "Mamani Rojas, Lizbeth Margarita"

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Biocontrol and plant growth-promoting potential of Bacillus and actinomycetes isolated from the rhizosphere and phyllosphere of potato (Solanum tuberosum L.) from different agroecological zones of Peru
(MDPI, 2025-12-23) Mamani Rojas, Lizbeth Margarita; Rengifo Sánchez, Raihil Rabindranath; Velarde Apaza, Leslie Diana; Ramírez Rojas, Max; Cántaro Segura, Hector
Potato (Solanum tuberosum L.) is a key staple crop in the Peruvian Andes, but its productivity is threatened by fungal pathogens such as Rhizoctonia solani and Alternaria alternata. In this study, 71 native bacterial strains (39 from phyllosphere and 32 from rhizosphere) were isolated from potato plants across five agroecological zones of Peru and characterized for their plant growth-promoting (PGPR) and antagonistic traits. Actinomycetes demonstrated broader enzymatic profiles, with 2ACPP4 and 2ACPP8 showing high proteolytic (68.4%, 63.4%), lipolytic (59.5%, 60.6%), chitinolytic (32.7%, 35.5%) and amylolytic activity (76.3%, 71.5%). Strain 5ACPP5 (Streptomyces decoyicus) produced 42.8% chitinase and solubilized both dicalcium (120.6%) and tricalcium phosphate (122.3%). The highest IAA production was recorded in Bacillus strain 2BPP8 (95.4 µg/mL), while 5ACPP6 was the highest among Actinomycetes (83.4 µg/mL). Siderophore production was highest in 5ACPP5 (412.4%) and 2ACPP4 (406.8%). In vitro antagonism assays showed that 5ACPP5 inhibited R. solani and A. alternata by 86.4% and 68.9%, respectively, while Bacillus strain BPP4 reached 51.0% inhibition against A. alternata. In greenhouse trials, strain 4BPP8 significantly increased fresh tuber weight (11.91 g), while 5ACPP5 enhanced root biomass and reduced stem canker severity. Molecular identification confirmed BPP4 as Bacillus halotolerans and 5ACPP5 as Streptomyces decoyicus. These strains represent promising candidates for the development of bioinoculants for sustainable potato cultivation in Andean systems.
Divergent effects of a Bacillus biofertilizer immobilized in guinea pig manure biochar: Boosting productivity vs. enhancing nutritional quality in maca monocultures
(Elsevier B.V., 2026-07-03) Solórzano Acosta, Richard Andi; Carranza Ramirez, Ana; Vera Obando, Nora; Javier Astete, Rosario Elyzabeth; Arias Arredondo, Alberto Gilmer; Lopez Rodriguez, Melina; Arroyo Julca, Michell Karolay; Saavedra Flores, Excela Elizabeth; Quispe Apaza , Cinthia Sheila; Mamani Rojas, Lizbeth Margarita; Cruz Luis, Juancarlos Alejandro; Montes Osorio, Angel; Agapito Panta, Juan; Oscco Laura, Persing; Hernández Amasifuen, Angel David
Intensive monoculture of maca (Lepidium meyenii) in the Peruvian Andes induces edaphic degradation, requiring sustainable amendments. We evaluated the agronomic and nutritional effects of a Bacillus subtilis biofertilizer immobilized in guinea-pig manure biochar, contrasting it with its individual components. A field experiment was conducted in Junín, Peru (4449 m a.s.l.) using a randomized complete block design with four treatments: control, biochar alone (3 L m⁻²), liquid B. subtilis (125 L ha⁻¹, 10⁷ CFU mL⁻¹) and biochar + B. subtilis. Plant establishment, yield, nutritional quality, and hypocotyl nutrient content were evaluated. Results revealed a functional divergence between treatments. Biochar-based treatments (alone and combined) significantly increased plant density (up to 49 vs. 29 m⁻² in the control) and yield (1290–1500 vs. 550 kg ha⁻¹), associated with greater K accumulation (up to 22,252 mg kg⁻¹; p < 0.001). In contrast, B. subtilis alone primarily enhanced nutritional quality, resulting in the highest protein (3.88 g 100 g⁻¹) and fat (0.24 g 100 g⁻¹) contents. The combined treatment achieved the highest individual plant weight (10.1 g) and high yields; however, it did not retain the quality-related benefits, exhibiting the lowest protein content (3.34 g 100 g⁻¹). Redundancy analysis (RDA) confirmed this functional separation: biochar was associated with a mineral–productivity gradient, whereas B. subtilis aligned with a proximate–nutritional gradient. These findings indicate that biochar primarily acts as edaphic conditioner driving productivity, while B. subtilis enhances nutritional quality. The absence of full synergism in the combined treatment suggests independent modes of action, resulting in a yield–quality trade-off. This enables the design of differentiated fertilization strategies tailored either toward maximum productivity (biochar alone) or premium nutritional quality (B. subtilis alone).