Significance and Impact of the Study: Protamine is a cationic antimicrobial peptide (CAP), which is active against a variety of bacteria. This is the first in-depth study of the interaction of protamine with a marine bacterium, Pseudoalteromonas sp. NCIMB 2021. Our results show that protamine is only active in seawater in the absence of divalent cations. In the presence of the divalent cations, Mg 2+ and Ca 2+ , protamine enhances the growth of Pseudoalteromonas sp. NCIMB 2021 and produces chains rather than individual cells. These are important considerations when deciding on applications for protamine and in terms of understanding its mechanism of action.

Fiber-optic sensors for dissolved CO 2 are an emergent technology for monitoring marine geologic CO 2 sequestration sites. Fiberoptic sensing technology has been used successfully in the oil and gas sector and is advantageous because it is capable of costeffective, instantaneous, distributed sensing. This is an improvement over current practice, which normally requires samples to be pumped to the surface for analysis. Biofouling of fiber-based sensors is a concern for the marine environment, as the biofouling can cause signal drift and also adversely impact the sensor's ability to detect dissolved CO 2 . Single mode optical fibers with long period gratings etched onto the core of the fiber were used for this study. Pseudoalteromonas sp. NCIMB 2021 was cultured and grown on sensing elements using nutrient-dense synthetic seawater. Biofouling was shown to cause shifts in the baseline signal. Post-fouling sensitivity of the sensor was also reduced relative to pre-fouling levels. Mechanical cleaning of the sensors restored sensor sensitivity to that seen prior to bacterial colonization.

Bacterial biofilms are precursors to biofouling by other microorganisms. Understanding their initiation may allow us to design better ways to inhibit them, and thus to inhibit subsequent biofouling. In this study, the ability of confocal Raman microscopy to follow the initiation of biofouling by a marine bacterium, Pseudoalteromonas sp. NCIMB 2021 (NCIMB 2021), in a flow cell, using optical and confocal Raman microscopy, was investigated. The base of the flow cell comprised a cover glass. The cell was inoculated and the bacteria attached to, and grew on, the cover glass. Bright field images and Raman spectra were collected directly from the hydrated biofilms over several days. Although macroscopically the laser had no effect on the biofilm, within the first 24 h cells migrated away from the position of the laser beam. In the absence of flow, a buildup of extracellular substances occurred at the base of the biofilm. When different coatings were applied to cover glasses before they were assembled into the flow cells, the growth rate, structure, and composition of the resulting biofilm was affected. In particular, the ratio of Resonance Raman peaks from cytochrome c (CC) in the extracellular polymeric substances, to the Raman phenylalanine (Phe) peak from protein in the bacteria, depended on both the nature of the surface and the age of the biofilm. The ratios were highest for 24 h colonies on a hydrophobic surface. Absorption of a surfactant with an ethyleneoxy chain into the hydrophobic coating created a surface similar to that given with a simple PEG coating, where bacteria grew in colonies away from the surface rather than along the surface, and CC:Phe ratios were initially low but increased at least fivefold in the first 48 h.

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