Antibiofilm Activity of the Marine Probiotic Bacillus subtilis C3 Against the Aquaculture-Relevant Pathogen Vibrio harveyi

V. harveyi is a well-known pathogen-inducing vibriosis, especially for shrimp, fish, and invertebrates. Its virulence is related to biofilm formation and this negatively impacts the aquaculture industry. Therapeutic strategies such as the utilization of probiotic bacteria may slow down Vibrio infections. In this study, we investigated the potential antibiofilm activity of the probiotic Bacillus subtilis C3 for aquaculture. First, B. subtilis C3 biofilm was characterized by confocal laser scanning microscopy (CLSM) before testing its bioactivities. We demonstrated antibiofilm activity of B. subtilis C3 culture supernatant, which is mainly composed-among other molecules-of lipopeptidic surfactants belonging to the surfactin family as identified by ultra-high-performance liquid chromatography (UHPLC)-MS/MS. Their antibiofilm activity was confirmed on V. harveyi ORM4 (pFD086) biofilm by CLSM. These findings suggest that the marine probiotic B. subtilis C3 might inhibit or reduce Vibrio colonization and thus decrease the associated animal mortalities.

Extracts from Wallis Sponges Inhibit Vibrio harveyi Biofilm Formation

Pathogenic bacteria and their biofilms are involved in many human and animal diseases and are a major public health problem with, among other things, the development of antibiotic resistance. These biofilms are known to induce chronic infections for which classical treatments using antibiotic therapy are often ineffective. Sponges are sessile filter-feeding marine organisms known for their dynamic symbiotic partnerships with diverse microorganisms and their production of numerous metabolites of interest. In this study, we investigated the antibiofilm efficacy of different extracts from sponges, isolated in Wallis, without biocidal activity. Out of the 47 tested extracts, from 28 different genera, 11 showed a strong activity against Vibrio harveyi biofilm formation. Moreover, one of these extracts also inhibited two quorum-sensing pathways of V. harveyi.

Impact of Co-Culture on the Metabolism of Marine Microorganisms

Natural products from plants have been listed for hundreds of years as a source of biologically active molecules. In recent years, the marine environment has demonstrated its ability to provide new structural entities. More than 70% of our planet’s surface is covered by oceans, and with the technical advances in diving and remotely operated vehicles, it is becoming easier to collect samples. Although the risk of rediscovery is significant, the discovery of silent gene clusters and innovative analytical techniques has renewed interest in natural product research. Different strategies have been proposed to activate these silent genes, including co-culture, or mixed fermentation, a cultivation-based approach. This review highlights the potential of co-culture of marine microorganisms to induce the production of new metabolites as well as to increase the yields of respective target metabolites with pharmacological potential, and moreover to indirectly improve the biological activity of a crude extract.

Pharmacokinetics of phenylbutazone in healthy subjects after oral administration of single and multiple doses

Plasma concentration profiles were studied after single and oral doses of phenylbutazone of 100, 300, and 600 mg in cachets to six healthy volunteers. The pharmacokinetics of phenylbutazone can be described by a two-compartment open model. The drug is absorbed rapidly and distributed partially into an extravascular compartment; about one-third remains in the plasma. The mean elimination half-life was 77 hr (54-99 hr), and there was a linear relationship between the dose and the area under the plasma concentration curve. In a multiple-dose study, six healthy volunteers received 150 mg of phenylbutazone in cachets twice daily every 11-13 hr for 17 days. A steady state was reached after approximately 200 hr of chronic treatment. The resultant steady-state plasma concentration were about four times higher than the peak concentration produced by a single 150-mg dose. The half-lives corresponding to the apparent elimination rate constant for the first and last administrations did not differ in each subject. The theoretical minimum concentrations are higher than the pseudosteady state reached during chronic treatment.

GLC determination of phenylbutazone in human plasma

A GLC method for phenylbutazone at concentrations down to 10 ng/ml in human plasma is described. After addition of an internal standard, phenylbutazone is extracted at pH 5 into benzene. The dry extract is dissolved in benzene, and phenylbutazone is determined by GLC using a 63Ni-electron-capture detector.

GLC determination of free and conjugated triclosan in human plasma and urine

A method for the determination of free and conjugated triclosan at concentrations as low as 2 ng/ml in human plasma or urine is described. Conjugated metabolites are split by enzyme hydrolysis. After addition of an internal standard, triclosan is extracted at acid pH into petroleum ether, transferred to an alkaline aqueous solution, and back-estracted into petroleum ether after acidification. Both compounds are acetylated with acetic anhydride in the presence of pyridine. The acetyl derivatives are determined by GLC using a 63Ni-electron-capture detector.