Characterization of Biofilm Extracts from Two Marine Bacteria

Abstract

In the marine environment, biofilm formation is an important lifestyle for microorganisms. A biofilm is comprised of cells embedded in an extracellular matrix that holds them close together and keeps the biofilm attached to the colonized surface. This predominant lifestyle and its main regulation pathway, namely quorum-sensing (QS), have been shown to induce specific bioactive metabolites. In this study, we investigated the biofilm formation by two marine bacteria belonging to the Vibrio species to discover potentially innovative bioactive compounds. We proposed a protocol to isolate biofilm extracts, to analyze their biochemical composition, and to compare them to planktonic cell extracts. Cells were grown attached to a plastic surface; extracts were prepared in water, NaOH, or in ethyl acetate and analyzed. Extracellular matrix components featured carbohydrates, proteins, lipids, and low amount of DNA. Carbohydrates appeared to be the main constituent of biofilm but also of the planktonic cell supernatant. Moreover, antimicrobial and QS-signaling activities were evidenced in extracts.

Effects of Extracellular Self- and Nonself-DNA on the Freshwater Microalga Chlamydomonas reinhardtii and on the Marine Microalga Nannochloropsis gaditana

“…The exDNA has been found in nearly all terrestrial and aquatic habitats [ 2 ]. In marine and freshwater environments it is reported to be freely present in the water column as well as in sediments [ 62 , 63 , 66 , 67 , 68 , 70 ]. Its persistence in the environment is influenced by surrounding conditions, for example, the adsorption to particles [ 71 , 72 ], the presence of bacterial nucleases [ 75 , 76 ], and the temperature and salinity of the water [ 76 , 77 ].…”

“…In the marine context, the DNA not enclosed in living cells represents the 90% of the total DNA pool [ 65 ], and includes DNA released in situ (autochthonous) by sediment microbial communities or by local living species, as well as DNA of pelagic and of terrestrial origin transiently deposited to the seafloor (allochthonous) [ 66 ]. It can been found as free molecules in the water column, or in sediments, when complexed with colloids and particles [ 64 , 65 , 67 , 68 , 69 ], or in extracellular polymeric matrices of marine bacteria biofilms [ 70 ]. ExDNA preservation, concentration, and size depend on the physio-chemical features of the specific environment [ 63 , 64 , 67 , 68 , 69 , 71 ].…”

A Reproducible Method for Growing Biofilms on Polystyrene Surfaces: Biomass and Bacterial Viability Evolution of Pseudomonas fluorescens and Staphylococcus epidermidis

“…Additionally, some authors pooled together the scraped biofilm contents of three wells to have a single replicate [53]. Finally, although using petri dishes or tubes could guarantee a wide area coverage, it does not offer control over the biofilms growing on the side walls as previously mentioned [18]. For applications, e.g., in coating science and technology for anti-biofilm applications or regarding non-thermal inactivation technologies (such as light treatment), the development of a biofilm on a flat surface is of extreme importance [40][41][42].…”

“…Since recent decades have witnessed a huge growth in the number of publications concerning biofilms, having a reproducible method to grow biofilms is of the utmost importance. The current methods for growing biofilms are based on the usage of CDC reactors [12], flow cell systems [17], microwell plates [11,12], tubes and petri dishes [18]. CDC reactors and flow cells, such as microfluidic devices, are systems in which the nutrients and bacteria are always replenished through a feed flow; these devices allow the control of the feed rate, the pH and the concentration of nutrients.…”

Nanogels: A novel approach in antimicrobial delivery systems and antimicrobial coatings

“…For food packaging materials, biofilm formation creates a health risk for the consumer and also reduces the production efficacy of the industry itself [ 6 ]. For the marine industry, biofilm can be the cause of corrosion and biofouling of marine equipment, resulting in its degradation and high economic costs [ 7 ]. Bacteria accumulation in water purification systems decreases the quality of home drinking water creating health threats [ 8 ].…”