A new approach to classifying polymer type of microplastics based on Faster-RCNN-FPN and spectroscopic imagery under ultraviolet light

Hazardous compounds from microplastics in coastal and marine environments are adsorbed by live organisms, affecting human and marine life. It takes time, money and effort to study the distribution and type of microplastics in the environment, using appropriate expensive equipment in a laboratory. However, deep learning can assist in identifying and quantifying microplastics from an image. This paper presents a novel microplastic classification method that combines the benefits of UV light with deep learning. The Faster-RCNN model with a ResNet-50-FPN backbone was implemented to detect and identify microplastics. Microplastic images from the field taken under UV light were used to train and validate the model. This classification model achieved a high precision of 85.5-87.8%, and the mAP scores were 33.9% on an internal test set and 35.7% on an external test set. This classification approach provides a high-accuracy, low-cost, and time-effective automated identification and counting of microplastics.

Enhanced Production of Gamma-Aminobutyric Acid (GABA) from Lactobacillus futsaii CS3 Using Agri-Food Industries By-Products Under Batch and Fed-Batch Fermentation

Gamma-aminobutyric acid (GABA) has diverse physiological functions, but its production by lactic acid bacteria is costly due to the culture medium. This study aimed to enhance GABA production by L. futsaii CS3 using low-cost substrates and agri-food industries by-products. Optimal culture conditions were determined using response surface methodology with a central composite design (CCD). Batch and fed-batch fermentation techniques were employed. In the MRS medium with 2% (w/v) monosodium glutamate (MSG), L. futsaii CS3 produced 6.84 g/l of GABA. Further optimization revealed that 2% (w/v) cane sugar resulted in a maximum GABA production of 9.6 g/l, while cane molasses yielded 7.4 g/l. The modified MRS medium with 2% (w/v) MSG, 2% (w/v) cane sugar, 3.06% (w/v) tuna condensate, and 2.5% (w/v) surimi washing water exhibited the highest GABA concentration of 11 g/l. Surimi washing water had a lower GABA concentration of 4.12 g/l. Critical factors identified through CCD analysis were cane sugar, tuna condensate, and MSG. The optimized modified MRS medium consisted of 3.48% (w/v) cane sugar, 3.84% (w/v) tuna condensate, and 10.77% (w/v) MSG, resulting in an actual GABA concentration of 18.27 g/l. Under flask-scale and batch fermentation conditions (initial pH 5, temperature 37 °C), GABA concentrations of 20.63 g/l and 17.24 g/l were obtained after 48 h, respectively. In fed-batch fermentation, GABA concentrations reached 23.01 g/l at 72 h. The addition of cane sugar and tuna condensate effectively enhanced GABA production in L. futsaii CS3, highlighting their suitability as cost-effective substrates for industrial-scale GABA production.

Graphical Abstract

An irreversible paper-based profluorescent nitroxide probe for the selective detection of ascorbic acid

Ascorbic acid (AA) or vitamin C plays multiple crucial roles, particularly as an antioxidant. This essentially biologically active molecule was selectively detected over other reductants by the synthesized profluorescent nitroxide probe ProN6via a switch-on method. After either a hydrogen atom or single electron transfer from AA to nitroxide, the resulting diamagnetic hydroxylamine was rapidly cyclized to form a fluorescent O-acylalkoxyamine. This cyclization prevented the reoxidation of the corresponding hydroxylamine to the nitroxide, leading to a high precision of detection. A kinetic fluorescence study indicated that ProN6 exhibited higher reactivity than ProN7. Density functional theory (DFT) calculations indicated that the Gibbs free energy of the AA-induced cascade reductive lactonization of ProN6 was lower than that of ProN5 and ProN7. The designed probe achieved the sensitive and specific detection of AA with detection limits of 77.9 nM and 195.9 μM in solution and on paper, respectively. The utilization of the probe as a paper-based fluorescent sensor demonstrated the good accuracy of the quantitative analysis of AA in commercial supplements.

Promoting Magnusiomyces spicifer AW2 Cell-Bound Lipase Production by Co-culturing with Staphylococcus hominis AUP19 and Its Application in Solvent-Free Biodiesel Synthesis

Yeast-bacterium interaction has recently been investigated to benefit the production of cell-bound lipases (CBLs). Staphylococcus hominis AUP19 supported the growth of Magnusiomyces spicifer AW2 in a palm oil mill effluent (POME) medium to produce CBLs through a bioremediation approach, including oil and grease (O&G) and chemical oxygen demand (COD) removals. This research used the yeast-bacterium co-culture to optimize CBLs and cell biomass (CBM) productions through bioremediation using the statistical Plackett-Burman design and response surface methodology-central composite design. The CBLs were finally applied in biodiesel synthesis. The CBM of 13.8 g/L with CBLs activity at 3391 U/L was achieved after incubation at room temperature (RT, 30 ± 2 °C) for 140 h in 50% POME medium, pH 7.0, containing 1.23% (w/v) ammonium sulfate. Bacterium promoted yeast growth to achieve bioremediation with 87.9% O&G removal and 84.5% COD removal. Time course study showed that the CBLs activity was highest at 24 h cultivation (4103 U/L) and retained 80% and 60% of activities at 4 °C and RT after 5 weeks of storage. The CBLs application successfully yielded 77.3% biodiesel from oleic acid (esterification) and 86.4% biodiesel from palm oil (transesterification) within 72 h in solvent-free systems. This study highlights that yeast-bacterium co-culture and POME should receive more attention for potential low-cost CBLs production through bioremediation, i.e., O&G and COD removals, while the CBLs as biocatalysts are promising for significant contribution to an effective strategy for economic green biodiesel production.

Persistence of maternal milk derived Lactobacillus plantarum in the infant feces and its antagonistic activity against Escherichia coli O157:H7

The diversity of lactic acid bacteria (LAB) in maternal milk and feces from Thai mother-infants pairs were revealed through nested PCR-DGGE. LAB species residing in maternal milk drawn from each individual demonstrated high uniqueness, yet shared similarity to her infant. Multiple strains of L. plantarum, L. fermentum, L. rhamnosus, L. mucosae, L. casei were continuously detected, suggesting direct transfer from a mother to her infant via breastfeeding. L. plantarum, the most commonly found species with many strain variants, remained persistent in infant's feces up to six months postpartum. Such success could be achieved through its ability to utilize fructooligosaccharides (FOS)/inulin together with antibacterial activity and competitive adhesion. With FOS/inulin, the prebiotic utilizing L. plantarum (M117 and M118) isolated from maternal milk effectively inhibited E. coli O157:H7 under highly microflora competitive and glucose-limited environments of colon model. The results introduce the potential trend for development of effective anti-diarrheal synbiotic infant formulae.

Metabolic profiles alteration of Southern Thailand traditional sweet pickled mango during the production process

Sweet pickled mango named Ma-Muang Bao Chae-Im (MBC), a delicacy from the Southern part of Thailand, has a unique aroma and taste. The employed immersion processes (brining 1, brining 2, and immersion in a hypertonic sugar solution, sequentially) in the MBC production process bring changes to the unripe mango, which indicate the occurrence of metabolic profiles alteration during the production process. This occurrence was never been explored. Thus, this study investigated metabolic profile alteration during the MBC production process. The untargeted metabolomics profiling method was used to reveal the changes in volatile and non-volatile metabolites. Headspace solid-phase micro-extraction tandem with gas chromatography quadrupole time of flight (GC/QTOF) was employed for the volatile analysis, while metabolites derivatization for non-volatile analysis. In conclusion, a total of 82 volatile and 41 non-volatile metabolites were identified during the production process. Terpenes, terpenoids, several non-volatile organic acids, and sugars were the major mango metabolites that presented throughout the process. Gamma-aminobutyric acid (GABA) was only observed during the brining processes, which suggested the microorganism’s stress response mechanism to an acidic environment and high chloride ions in brine. Esters and alcohols were abundant during the last immersion process, which had an important role in MBC flavor characteristics. The knowledge of metabolites development during the MBC production process would be beneficial for product development and optimization.