Marine macroalgae-associated fungi from Yacila and Los Cangrejos beaches (Northern Peru) and previously selected marine bacteria evaluated as plant growth promoters in maize under saline stress

The diversity of marine fungi associated with macroalgae in Peru remains largely unknown, and no studies have provided holistic data on their biodiversity or their role as plant growth promoters in maize under salinity stress conditions. Endophytic and epiphytic fungi were isolated from the macroalgae <i>Caulerpa</i> sp., <i>Ulva</i> sp., <i>Ahnfeltiopsis</i> sp., and <i>Chondracanthus chamissoi</i>, collected from Yacila and Cangrejos beaches (Piura, Peru), while marine bacteria were provided by the Microbial Biotechnology Research Laboratory of the National University of Frontera. The growth-promoting properties of these marine microorganisms were evaluated prior to their inoculation in maize. Fungal isolates were phylogenetically characterized by ITS sequencing as <i>Penicillium</i> sp. YAFL13, <i>Penicillium</i> sp. YUFE7, <i>Talaromyces stollii</i> YAFL19, <i>T. stollii</i> YAFL4, <i>T. amestolkiae</i> YCFR3, <i>Aspergillus sydowii</i> CCDF2, <i>A. sydowii</i> YFep2, and <i>A. sydowii</i> YFep3. In total, 12 marine fungi were isolated and used in the assays along with 10 marine bacteria. Based on antimicrobial activity, IAA synthesis, siderophore production, phosphate solubilization, and hydrolytic enzyme production, three fungal strains (<i>Penicillium</i> sp. YAFL13, <i>A. sydowii</i> CCDF2, and <i>A. sydowii</i> YFep2) and two bacterial strains (<i>Bacillus</i> sp. YCFR5 and <i>Pantoea agglomerans</i> YAFL6) were selected. Among them, <i>A. sydowii</i> CCDF2 significantly enhanced maize growth parameters, highlighting its promising potential as a plant inoculant. This study represents one of the few reports on marine microorganisms associated with marine macroalgae, revealing a valuable fungal diversity and its potential role in promoting maize growth under saline stress conditions.