Substrate degradation by seaweed-associated bacteria

The ability of bacteria to produce extracellular enzymes that can degrade substrates such as seaweed polymers (cellulose, laminarin, alginate, fucoidan), plant polymers (starch, pectin), gelatin, plastics (polycaprolactone) can be visualised on an agar plate. Activity is usually evidenced from a zone of clearance around the bacterial growth, or a precipitate formation around the growth. In the case of some of the polymers, a dye needs to be added to the plate in order to visualise the zone of clearance (e.g., the addition of Gram's iodine to visualise starch degradation, or the addition of Congo Red to visualise seaweed polymer degradation. The images provided here represent the screening of seaweed-associated bacteria for their ability to degrade seaweed polymers, plant polymers, gelatin, and polycaprolactone.Gelatin_strain_agar: Images of a seaweed-associated strain grown on agar supplemented with gelatin. Ability to degrade gelatin can be seen from a zone of clearance around the bacterial growth streak. For reference, an uninoculated plate is next to the inoculated plate.Pectin_SJ1F24_agar: Image of strain SJ1F24 grown on agar supplemented with pectin from apples. Ability to degrade pectin can be seen from a zone of clearance and precipitate around the bacterial growth streak. For reference, an uninoculated plate is next to the SJ1F24 plate.Starch_strain_agar: Image of seaweed-associated strains grown on agar supplemented with starch from potato. Ability to degrade starch can be seen from a zone of clearance around the bacterial growth streak after the agar has been flooded with Gram’s iodine. For reference, an uninoculated plate is next to the inoculated plate.Degradation of seaweed polymers: The images taken using white light exposure in the Biorad GelDocXR after agar plates were flooded with a 0.1% (v/v) Congo Red solution. Zones of clearance are indicators of substrate degradation.The substrates are indicated in the name of the image files:AlginateAlginate+ (prepared in a Red Sea salt solution, 38.2g/L)AvicelAvicel+ (prepared in a Red Sea salt solution, 38.2g/L)CMC (carboxymethylcellulose)CMC+ (prepared in a Red Sea salt solution, 38.2g/L)FucoidanFucoidan+ (prepared in a Red Sea salt solution, 38.2g/L)LaminarinLaminarin+ (prepared in a Red Sea salt solution, 38.2g/L)Strain names are clearly visible on the plate images. For reference, a control plate is included in all images.Plastic degradation: Images of agar plates containing the plastic polymer, polycaprolactone (PCL). The agar plates are divided into four with each quadrant containing a bacterium isolated from seaweed. The naming convention of the images are as follow:Medium_strains_front or agarMedium = PCL (agar supplemented with PCL)Strain names listed clockwise, staring in the top left quadrantFront = the front part of the Petri dish where the plate is labelled (strain name listing is based on the front view)Agar = the agar side of the plate where the bacterial growth is visible. Strain names will correspond to strains in an anticlockwise position, starting in the upper righthand quadrant.Images of control plates are included (no inoculum); PCL+ indicates that the PCL agar was prepared in a Red Sea salts solution (38.2g/L).Zones of clearing around bacterial growth denotes the ability of the strain to degrade the plastic, PCL.