Boosting algicidal efficiency of Alteromonas sp. FDHY-CJ against Skeletonema costatum through fermentation optimization.

Algicidal bacteria exhibit promising potential against harmful algal blooms (HABs); however, their application has been limited due to their limited algicidal activity. This study demonstrates the enhanced algicidal activity of Alteromonas sp. FDHY-CJ bacteria against harmful Skeletonema costatum using a 5 L fermenter. Utilizing this refined framework increased the OD600 value and algal cell mortality by 6.50 and 2.88 times, respectively, compared to non-optimized culture cultivated in a flask using marine broth 2216E medium. The mechanism of action involves significant inhibition of algal photosynthetic efficiency with concurrent degradation of photosynthetic pigments. Relative to the non-optimized group, the optimized bacterial treatment led to a significant increase in H2O2 and MDA (malondialdehyde) by 19.54 and 4.22-fold, respectively, and resulted in membrane damage. The culture optimization procedure yielded effectual algicidal substances capable of considerably reducing the severity of S. costatum HABs through cell membrane disruption.

Pilot-Scale Fermentation of Pseudoalteromonas sp. Strain FDHY-MZ2: An Effective Strategy for Increasing Algicidal Activity.

The role of microorganisms in effectively terminating harmful algal blooms (HABs) is crucial for maintaining environmental stability. Recent studies have placed increased emphasis on bio-agents capable of inhibiting HABs. The bacterium Pseudoalteromonas sp. strain FDHY-MZ2 has exhibited impressive algicidal abilities against Karenia mikimotoi, a notorious global HAB-forming species. To augment this capability, cultures were progressively scaled from shake flask conditions to small-scale (5 L) and pilot-scale (50 L) fermentation. By employing a specifically tailored culture medium (2216E basal medium with 1.5% soluble starch and 0.5% peptone), under precise conditions (66 h, 20 °C, 450 rpm, 30 L/min ventilation, 3% seeding, and constant starch flow), a notable increase in algicidal bacterial biomass was observed; the bacterial dosage required to entirely wipe out K. mikimotoi within a day decreased from 1% to 0.025%. Compared to an unoptimized shake flask group, the optimized fermentation culture caused significant reductions in algal chlorophyll and protein levels (21.85% and 78.3%, respectively). Co-culturing induced increases in algal malondialdehyde and H2O2 by 5.98 and 5.38 times, respectively, leading to further disruption of algal photosynthesis. This study underscores the unexplored potential of systematically utilized microbial agents in mitigating HABs, providing a pathway for their wider application.

The use of immobilised bacteria cross-linked within magnetic alginate beads enhances the treatment of benzophenone-type UV filter chemicals by the SBR system.

Benzophenone-n compounds (BPs) are applied in a broad spectrum of commercial products, one of which is sunscreen. These chemicals are frequently detected in a variety of environmental matrices worldwide, especially water bodies. BPs are defined as emerging contaminants as well as endocrine-disrupting contaminants; thus, it has become necessary to develop aggressive and green treatments to remove BPs. In this study, we used immobilised BP-biodegrading bacteria linked to reusable magnetic alginate beads (MABs). The MABs were added to a sequencing batch reactor (SBR) system to enhance the removal of 2,4-dihydroxybenzophenone (BP-1) and oxybenzone (BP-3) from sewage. The BP-1 and BP-3 biodegrading bacteria in the MABs consisted of strains from up to three genera to allow for efficient biodegradation. The strains used were Pseudomonas spp., Gordonia sp., and Rhodococcus sp. The optimal composition of the MABs consisted of 3% (w/v) alginate and 10% (w/v) magnetite. The MABs resulted in 60.8%-81.7% recovery by weight after 28 days, and there was a continuous release of bacteria. Moreover, the biological treatment of the BPs sewage improved after adding 100 g of BP1-MABs (1:27) and also 100 g BP3-MABs (1:27) into the SBR system at a hydraulic retention time (HRT) of 8 h. Compared with the SBR system without MABs, the removal rates of BP-1 and BP-3 increased from 64.2% to 71.5% and from 78.1% to 84.1%, respectively. Furthermore, the COD removal increased from 36.1% to 42.1%, and total nitrogen increased from 30.5% to 33.2%. Total phosphorus remained constant at 29%. The bacterial community analysis showed that the Pseudomonas population was <2% before the MAB addition, but increased to 56.1% by day 14. In contrast, the Gordonia sp. And Rhodococcus sp. Populations (<2%) remained unchanged throughout the 14-day treatment period.