Production and structure prediction of amylases from Chlorella vulgaris

Amylases are enzymes required for starch degradation and are naturally produced by many microorganisms. These enzymes are used in several fields such as food processing, beverage, and medicine as well as in the formulation of enzymatic detergents proving their significance in modern biotechnology. In this study, a three-stage growth mode was applied to enhance starch production and amylase detection from Chlorella vulgaris. Stress conditions applied in the second stage of cultivation led to an accumulation of proteins (75% DW) and starch (21% DW) and a decrease in biomass. Amylase activities were detected and they showed high production levels especially on day 3 (35 U/ml) and day 5 (22.5 U/ml) of the second and third stages, respectively. The bioinformatic tools used to seek amylase protein sequences from TSA database of C. vulgaris revealed 7 putative genes encoding for 4 α-amylases, 2 β-amylases, and 1 isoamylase. An in silico investigation showed that these proteins are different in their lengths as well as in their cellular localizations and oligomeric states though they share common features like CSRs of GH13 family or active site of GH14 family. In brief, this study allowed for the production and in silico characterization of amylases from C. vulgaris.

Antibiotics in marine aquaculture farms surrounding Laizhou Bay, Bohai Sea: Distribution characteristics considering various culture modes and organism species

This study mainly investigated the distribution characteristics and risk assessment of 14 antibiotics in typical marine aquaculture farms surrounding the Bohai Sea. The effects of various culture modes (outdoor pond culture, recirculating water culture, greenhouse pond culture, raft culture, cage culture and bottom sowing culture), and diverse cultured organism species such as fish (grouper, bass, pike and turbot), mollusk (oyster, scallop, conch and mussel) and sea cucumber on the distribution of antibiotics in different mariculture pond matrices (seawater, sediment/biofilm and organism) were studied. In addition, antibiotic pollution levels in various matrices (water, sediment, organism and feed) from different mariculture areas surrounding the Bohai Sea and the Yellow Sea were compared. The biofilm on the inner wall of greenhouse pond was more capable of accumulating antibiotics than the biofilm attached to the rope for raft culture and net for cage culture, and other culture sediments. The antibiotic concentration level in the culture matrices (water, sediment/biofilm and organism) was the highest under greenhouse pond culture mode, and that under the industrial recirculating water culture mode was the lowest. Antibiotic concentration in culture matrices of fish ponds was higher than that of sea cucumber ponds and mollusk ponds. The levels of antibiotics in water and sediment from marine aquaculture farms in Laizhou (Bohai Sea coast) were higher than those in Haiyang and Jimo (Yellow Sea coast). Enrofloxacin in turbot might cause considerable harm to human health, and the risk of antibiotics in other seafood could be ignored. Antibiotic ecological risks and resistance risks were generally low in water. Fluoroquinolones posed medium to high ecological risks in the natural receiving water around the mariculture farm. Trimethoprim and enrofloxacin showed relatively high antibiotic resistance risks in mariculture water and natural water, which might exert selective pressure on the bacterial community in the environment.

Magnetic field intervention on growth of the filamentous microalgae Tribonema sp. in starch wastewater for algal biomass production and nutrients removal: Influence of ambient temperature and operational strategy

This paper investigated the effects of temperature and cultivation methods (batch or semi-continuous culture) on the filamentous microalgae Tribonema sp. biomass production and nutrients removal in starch wastewater under low intensity magnetic field (MF) intervention. The MF significantly promoted algal growth in the late logarithmic-phase of batch cultivation, and the effect was even more obvious at lower temperatures. The MF treated group at 30 °C accumulated the highest biomass of 4.44 g/L of batch culture, an increase of 15.0% compared with the control group. The oil content of Tribonema sp. was enhanced with the MF intervention, especially for the batch culture. In the semi-continuous culture under MF intervention, Tribonema sp. reached the high biomass of 18.45 g/L after 25 days. When gradually reducing hydraulic retention time (HRT) to 1 day, the average removal rates for COD, TN, NH₃-N and TP were all more than 90% in the semi-continuous cultivation.