# Laminar _Ulva_ Species: A Multi-Tool for Humankind?
## 2 The Biology of _Ulva_ sp.
### Algae Microbial Interaction
[PERSON] and [PERSON] 1980 [59], referenced by [PERSON] 1972 [60], and [PERSON] et al., 2015 [47] discovered that the distinctive foliage morphology of _Ulva_ was lost when grown under axenic conditions in a specified synthetic medium, but the introduction of bacteria restored differentiation. It should be emphasized that the propensity was observed prior to germ cell formation, alluding to the genetic regulation of cell differentiation in the natural bleb-like morphotype of _Ulva compressa_ (as _U. mutabilis_). [PERSON] et al., 2015 [47] also noted that although bacteria cannot pass endogenously to the next generation, direct contact between bacteria and seaweed or a message through secreted chemicals is essential for growth, development, and differentiation. In [PERSON] et al., 2003 [57], the discovery was reported that the substance that induces Thallus morphogenesis is secreted by _Cytoplasa_ sp. (YM2-23) of the _Cytoplasa_--_Flavobacterium_--Bacteroide complex. Therefore, we can say that these organisms are also responsible for the release of spores, recruitment, and initial establishment on an appropriate substrate [13]. [PERSON] et al., 2006 [61], when working with a specimen of _Ulva intestinalis_, noted that in addition to development and morphogenesis, bacteria-derived \"acyl-homoserine lactones\" also play a vital role in modulating the rate of settlement of zoological spores through a chemokinetic mechanism [13]. [PERSON] et al. [58] carried out a study stating that _Marinomonas_ sp. and _Bacillus_ spp. induced wild-type morphology and growth in _U. lactuca_ (formerly _Ulva fascita_) (it was the first study to demonstrate involvement in this species). [PERSON] et al. (1996) [62] also reported the involvement of _Bacillus_ spp. affecting morphology and growth in _Ulva australis_ (formerly _U. pertusa_). However, the effect of bacteria on the growth rate of macroalgae has not been well quantified [58]. [PERSON] et al. (2012) [63] conducted axenic cultivation of _Ulva_ and observed that complete morphogenesis was achieved through the combination of two bacterial strains, _Roseobacter_ sp. and _Cytoplasa_ sp., or via morphogenetic complexes obtained from the bacterial supernatant. These bacteria perform complementary functions: _Roseobacter_ sp. triggers cell division akin to the plant hormone cytokinin, while _Cytoplasa_ sp. fosters the development of a viable undifferentiated basal cell and primary rhizoid cells, akin to the plant hormone auxin, in addition to promoting proper cell wall formation. Notably, the _Roseobacter_ species displays a specific chemotactic attraction to the rhizoid cells of _Ulva compressa_ (formerly _U. mutabilis_) and appears to engage in chemical communication with both the _Cytoplasa_ strain and the alga, forming a distinctive tripartite symbiotic community [47; 54; 63]. Notably, while other \(\alpha\)-proteobacteria (such as _Sulfitobacter_ sp.) and \(\gamma\)-proteobacteria (like _Halomonas_ sp.) can substitute for _Roseobacter_, the presence of _Cytoplasa_ sp. seems to be indispensable. This implies that certain genes might play a crucial role in shaping the _Ulva_ community and its accompanying bacteria [47]. Furthermore, laboratory studies have demonstrated that different bacterial communities with similar functional attributes can facilitate successful algal morphogenesis in _Ulva compressa_ (as _U. mutabilis_) and _U. intestinalis_ as reported in [PERSON] et al., 2017 [64]. [PERSON] et al., 2017 [39] studied the metabolic profile of fragmentation-induced reproduction in _U. prolifera_, where they reported a dynamic change within 48 h. The metabolites,namely \(\gamma\)-aminobutyric acid (GABA), glutamic acid, gallic acid, and malic acid, were responsible for the formation and release of reproductive cells [39]. Surface metabolomic snapshots were employed to monitor the gametogenesis of _Ulva compressa_ (formerly known as _U. mutabilis_), during which lamina cells undergo synchronous differentiation into gametag, leading to the production of gametes.