Rawat Deepak, Sharma Udita, Poria Pankaj, Finlan Arran, Parker Brenda, Sharma Radhey Shyam, Mishra Vandana
Bioresources & Environmental Biotechnology Laboratory, Department of Environmental Studies, University of Delhi, Delhi, 110007 India.
Department of Biochemical Engineering, Bernard Katz Building, University College London, Gower Street, London, WC1E 6BT UK.
ISME Commun. 2022 Sep 15;2(1):83. doi: 10.1038/s43705-022-00161-0. eCollection 2022.
Phototrophic communities of autotrophic microalgae and heterotrophic bacteria perform complex tasks of nutrient acquisition and tackling environmental stress but remain underexplored as a basis for the bioremediation of emerging pollutants. In industrial monoculture designs, poor iron uptake by microalgae limits their productivity and biotechnological efficacy. Iron supplementation is expensive and ineffective because iron remains insoluble in an aqueous medium and is biologically unavailable. However, microalgae develop complex interkingdom associations with siderophore-producing bacteria that help solubilize iron and increase its bioavailability. Using dye degradation as a model, we combined environmental isolations and synthetic ecology as a workflow to design a simplified microbial community based on iron and carbon exchange. We established a mutualism between the previously non-associated alga and siderophore-producing bacterium . Siderophore-mediated increase in iron bioavailability alleviated Fe stress for algae and increased the reductive iron uptake mechanism and bioremediation potential. In exchange, produced galactose, glucose, and mannose as major extracellular monosaccharides, supporting bacterial growth. We propose that extracellular iron reduction by ferrireductase is crucial for azoreductase-mediated dye degradation in microalgae. These results demonstrate that iron bioavailability, often overlooked in cultivation, governs microalgal growth, enzymatic processes, and bioremediation potential. Our results suggest that phototrophic communities with an active association for iron and carbon exchange have the potential to overcome challenges associated with micronutrient availability, while scaling up bioremediation designs.
自养微藻和异养细菌的光合营养群落执行着复杂的养分获取和应对环境压力的任务，但作为新兴污染物生物修复的基础，它们仍未得到充分探索。在工业单一培养设计中，微藻对铁的吸收不佳限制了它们的生产力和生物技术功效。铁补充剂既昂贵又无效，因为铁在水性介质中仍然不溶且无法被生物利用。然而，微藻与产生铁载体的细菌形成了复杂的跨界关联，有助于溶解铁并提高其生物利用度。以染料降解为模型，我们将环境分离和合成生态学结合为一种工作流程，以设计一个基于铁和碳交换的简化微生物群落。我们在先前不相关的藻类和产生铁载体的细菌之间建立了共生关系。铁载体介导的铁生物利用度增加减轻了藻类的铁胁迫，并增强了还原性铁吸收机制和生物修复潜力。作为交换，藻类产生半乳糖、葡萄糖和甘露糖作为主要的细胞外单糖，支持细菌生长。我们提出，铁还原酶介导的细胞外铁还原对于微藻中偶氮还原酶介导的染料降解至关重要。这些结果表明，在培养中经常被忽视的铁生物利用度，控制着微藻的生长、酶促过程和生物修复潜力。我们的结果表明，具有活跃的铁和碳交换关联的光合营养群落有潜力克服与微量营养素可用性相关的挑战，同时扩大生物修复设计规模。
