Microalgae are used in various biotechnological processes, such as biofuel production due to their high biomass yields, agriculture as biofertilizers, production of high-value-added products, de-contamination of wastewater, or as biological models for carbon sequestration. The number of these biotechnological applications is increasing, and as such, any advances that contribute to reducing costs and increasing economic profitability can have a significant impact. Nitrogen fixing organisms, often called diazotroph, also have great biotechnological potential, mainly in agri-culture as an alternative to chemical fertilizers. Microbial consortia typically perform more com-plex tasks than monocultures and can execute functions that are challenging or even impossible for individual strains or species. Interestingly, microalgae and diazotrophic organisms are capable to embrace different types of symbiotic associations. Certain corals and lichens exhibit this sym-biotic relationship in nature, which enhances their fitness. However, this relationship can also be artificially created in laboratory conditions with the objective of enhancing some of the biotech-nological processes that each organism carries out independently. As a result, the utilization of microalgae and diazotrophic organisms in consortia is garnering significant interest as a potential alternative for reducing production costs and increasing yields of microalgae biomass, as well as for producing derived products and serving biotechnological purposes. This review makes an effort to examine the associations of microalgae and diazotrophic organisms, with the aim of highlighting the potential of these associations in improving various biotechnological processes.

Biofertilizer, an environment-friendly and renewable plant nutrient source, has been widely applied and studied to reduce dependency on chemical fertilizers. However, most studies focus on the effects of biofertilizer on the bacterial and fungal communities, and we still lack an understanding of biofertilizer on the protistan community. Here, the effects of biofertilizer application on the composition and interaction of the protistan community in the wheat rhizosphere were investigated based on a 4-year field experiment. Biofertilizer application altered soil physicochemical properties and the protistan community composition (ANOSIM, p < 0.001), and significantly induced an alpha diversity decline. Random forecast and redundancy analysis demonstrated that nitrogenase activity and available phosphorus were the main drivers. Trichomonas classified to the phylum Metamonada was enriched by biofertilizer, and was significantly positive connections with soil nitrogenase activity and some function genes involved in nitrogen-fixation and nitrogen-dissimilation. Biofertilization loosely connected biotic interactions, while did not affect the stability of the protistan community. Besides, biofertilizer promoted the connections of protists with fungi, bacteria, and archaea. Combined with the conjunct biotic network (protist, fungi, bacteria, and archaea) and interactions between protists and soil physicochemical properties/function genes, protists may act as keystone taxa potentially driving soil microbiome composition and function.

Here, we report the draft genome sequence of the type strain of Ideonella azotifigens DSMZ21438^T (formally 1a22^T = JCM15503^T). Ideonella azotifigens DSMZ21438T a novel betaproteobacterial non-symbiotic nitrogen-fixing grass rhizosphere dwelling microbe. The 891,561 paired-end shotgun reads were quality filtered and decontaminated with the ATLAS pipeline, then assembled with Unicycler. The genome size is 6,257,981 bp, an N50 size of 7,849 bp, with a G+C content of 66.71%, and with 5,882 predicted protein-coding genes. I. azotifigens DSMZ21438^T represents the first member of the genus isolated from rhizosphere soil, providing a framework for further study into non-alphaproteobacterial nitrogen fixation and synthetic biology applications.

Paenibacillus sp. tmac-D7 was isolated from coastline growing Trifolium macraei (double-head clover) root nodules from Bodega Bay, California. The draft genome is 5,567,337 bp with a G+C% of 52.4%, an N50 of 114,261 bp, and 5,282 predicted protein-coding genes. Paenibacillus, while found in many other environments, is frequently isolated from root nodules, with many acting as plant pathogen antagonists. Paenibacillus sp. tmac-D7 is the first genome of a non-rhizobial endophyte isolate from wild Trifolium macraei (double-head clover).