Bioactivity, Chemical Profiling, and 16S rRNA-Based Phylogeny of Pseudoalteromonas Strains Collected on a Global Research Cruise

Abstract

1One hundred one antibacterial Pseudoalteromonas strains that inhibited growth of a Vibrio 2 anguillarum test strain were collected on a global research cruise (Galathea 3), and 51 of the strains 3 repeatedly demonstrated antibacterial activity. Here, we profile secondary metabolites of these 4 strains to determine if particular compounds serve as strain or species markers and to determine if 5 the secondary metabolite profile of one strain represents the bioactivity of the entire species. 16S 6 rRNA gene similarity divided the strains into two primary groups: One group (51 strains) consisted 7 of bacteria which retained antibacterial activity, 48 of which were pigmented, and another group (50 8 strains) of bacteria which lost antibacterial activity upon sub-culturing, two of which were 9pigmented. The group that retained antibacterial activity consisted of six clusters in which strains 10 were identified as Pseudoalteromonas luteoviolacea, Pseudoalteromonas aurantia, 11 Pseudoalteromonas phenolica, Pseudoalteromonas ruthenica, Pseudoalteromonas rubra and 12Pseudoalteromonas piscicida. HPLC-UV/VIS analyses identified key peaks, such as violacein in P. 13 luteoviolacea. Some compounds, such as a novel bromoalterochromide were detected in several 14 species. HPLC-UV/VIS detected systematic intra-species differences for some groups and testing 15 several strains of a species was required to determine these differences. The majority of non-16 antibacterial, non-pigmented strains were identified as Pseudoalteromonas agarivorans and HPLC-17 UV/VIS did not further differentiate this group. Pseudoalteromonas retaining antibacterial were 18 more likely to originate from biotic or abiotic surfaces in contrast to planktonic strains. Hence, the 19 pigmented, antibacterial Pseudoalteromonas have a niche specificity, and sampling from marine 20 biofilm environments is a strategy for isolating novel marine bacteria that produce antibacterial 21 compounds. 22 23Words: 252 24 25

Culturable heterotrophic bacteria from Potter Cove, Antarctica, and their hydrolytic enzymes production

“…In addition, the isolates belonging to the most commonly recovered genera, Pseudoalteromonas and Psychrobacter, were retrieved from almost all the samples tested, showing their ubiquitous distribution in the coastal ecosystems of Potter Cove. These results agree with those reported by other authors who have isolated several species of these genera from many Antarctic environments (Bozal et al 1997;Bowman 1998;Bozal et al 2003;Vynne et al 2011). Among the isolates obtained in each Antarctic expedition, we found enzyme producers in all groups except NR, in which all isolates were obtained from the fish Notothenia rossi.…”

Mini-review: Inhibition of biofouling by marine microorganisms

“…Some bacterial strains isolated from seawater inhibited the growth of marine and human pathogens (Table 1; Gram et al 2010;Bernbom et al 2011;Vynne et al 2011). The highest antibacterial activity was observed among Pseudoalteromonas and Ruegeria isolates.…”

“…For example, a strain of B. licheniformis lost its bioactivity when it was cultured in a liquid medium instead of on agar surfaces (Yan & Boyd 2002;Matz et al 2008). Similarly, Pseudoalteromonas isolates attached to biotic or abiotic surfaces are more likely to have antibacterial properties than planktonic isolates (Vynne et al 2011). Mucus of the coral Acropora palmata inhibited antibiotic and pigment production by the 'visitor' isolate Pseudoalteromonas sp.…”

Pseudoalteromonas spp. Serve as Initial Bacterial Attractants in Mesocosms of Coastal Waters but Have Subsequent Antifouling Capacity in Mesocosms and when Embedded in Paint

“…Similarly, Grossart et al (38) found that the production of antibiotic by a biofilm community did not affect newcomers to the biofilm. Of the four Pseudoalteromonas species in the present study, three (P. piscicida, P. tunicata, and P. ulvae) represent the pigmented, antibiotic-producing subgroup, whereas P. antarctica, despite a brownish colony color, represents the nonpigmented, non-antibiotic-producing cluster (46,47). In the simple (sterile seawater) systems, we observed no consistent difference in repelling or attracting characteristics between P. antarctica and the pigmented strains, further supporting the above-mentioned studies that could not correlate antibiotic production to a subsequent repelling effect (38,45).…”

“…A high-M w protein has been identified as an antibacterial compound (48), and an alkaloid (norharman) was identified as a cytotoxic compound (49). P. piscicida also produces brominated peptides (46,47) that have a cytotoxic effect (50). Despite several attempts, we have not been able to purify the antibacterial compound(s).…”