The aim of this study was to develop a technical system for high-efficient production of fucoxanthin by photo-fermentation of Phaeodactylum tricornutum. In a 5 L photo-fermentation tank, the effects of initial light intensity, nitrogen source and concentration as well as light quality on biomass concentration and fucoxanthin accumulation in P. tricornutum were investigated systematically under mixotrophic condition. The results showed that the biomass concentration, fucoxanthin content and productivity reached the highest level of 3.80 g/L, 13.44 mg/g and 4.70 mg/(L·d) under the optimal conditions of initial light intensity of 100 μmol/(m²·s), 0.02 mol TN/L of tryptone: urea (1:1, N mol/N mol) as mixed nitrogen source, and a mixed red/blue (R: B=6:1) light, 1.41, 1.33 and 2.05-fold higher than that before optimization, respectively. This study developed a key technology for enhancing the production of fucoxanthin by photo-fermentation of P. tricornutum, facilitating the development of marine natural products.
Fermentation ; Xanthophylls ; Light ; Diatoms ; Nitrogen

Diatomology has provided important evidences for diagnosis of drowning in forensic practice. However, conflicting opinions about the reliability of diatom test still exist. As a part of efforts to end this controversy, it is very important to secure the diatom profile in the water sample of drowning site. Our results obtained in this study show the characteristics of temporal and spatial distribution of diatom collected from the main drowning sites of Han river in Korea. During spring, 111 taxa (98 species and 13 varieties) were identified from 31 genera, and 87 taxa (77 species and 10 varieties) were identified from 22 genera during summer. At the level of genus Achnanthes, Cyclotella, Cymbella, Fragilaria, Navicula, Nitzschia, and Stephanodiscus represented the highest numbers, and were the most widely occurred during two seasons. The centric diatoms, Stephanodiscus hantzschii f. tenuis and Cyclotella atomus were typical of spring and summer, respectively, and identified as dominant indicator species. The commonly occurred species, including dominant species in the seasonal cluster analysis influenced the formation of site - specific groups. As a result, our results will be able to be used not only as the comparison data of diatom found in the drowning victim's tissue but also a reference data to rule out the possibility of contamination.
Diatoms ; Drowning ; Korea ; Rivers ; Seasons ; Water

OBJECTIVES: To study the effects of temperature and time for diatoms digestion and find out suitable digestive temperature and time. METHODS: Eighty pieces of liver tissues were collected, each piece of tissue was 2 g, and 2 mL Pearl River water was added to each piece of tissue. The digestion temperature was set at 100 ℃, 120 ℃, 140 ℃, 160 ℃, 180 ℃ and the digestion time was set at 40, 50, 60, 70, 80 min. The liver tissue and water mixture were divided into 8 portions in each group. All the samples were tested by microwave digestive - vacuum filtration - automated scanning electron microscopy method. The quantity of diatom recovered and the quality of residue on the membrane were recorded. RESULTS: When the digestion time was set to 60 min, there were statistically significant differences in the number of diatoms recovered at different temperatures (P<0.05). The maximum number of diatoms recovered was (28 797.50±6 009.67) at 140 ℃, and the minimum residue was (0.60±0.28) mg at 180 ℃. When the digestion temperature was set at 140 ℃, there were statistically significant differences in the number of diatoms recovered at different digestion times (P<0.05). The number of diatoms recovered was the highest at 40 min, it was up to (20 650.88±1 950.29), and the residue quality of each group had no statistical significance among different digestion time groups(P>0.05). CONCLUSIONS The effect of diatom digestion is related to temperature and time. When the digestion temperature was 140 ℃ and the digestion time was 40, 50 and 60 min, it is favorable for diatom test.
Diatoms ; Drowning ; Forensic Pathology/methods* ; Temperature ; Water

OBJECTIVES: To establish a diatom database by analyzing the quatity, species distribution and differences of diatom in water samples of the whole navigable sections of the Beijing-Hangzhou Grand Canal, to provide a reference for the inference of the drowning site. METHODS: Water samples were collected at 22 sites in the navigable sections of the Beijing-Hangzhou Grand Canal (Jining section to Yangzhou Section), and the diatoms at each site were qualitatively and quantitatively analyzed by using graphite digestion-scanning electron microscopy. RESULTS: Sampling site T (Laohuaijiang River Line, Gaoyou City, Yangzhou City, Jiangsu Province) had the highest number of diatoms, while sampling site O (Siyang County, Suqian City, Jiangsu Province) had the lowest number of diatoms, with a large gap of 68 times. At sampling site Q (Jiangpu District, Huaian city, Jiangsu Province), there were 19 species of diatoms. The sampling site O had the least diatoms, with 7 species. There were no significant differences in species evenness and species diversity at each sampling site (P>0.05). Some sampling sites have characterized diatoms, such as Caloneis at station A (Taibai Lake, Weishan County, Shandong Province), Rhoicosphenia at station B (Nanyang Town, Weishan County, Shandong Province), Amphora at station I (Taierzhuang District, Zaozhuang City, Shandong Province) and Epithemia at station J (Pizhou 310 national highway, Xuzhou City, Jiangsu Province). CONCLUSIONS The species richness of diatoms gradually increased from north to south. Diatom species richness and species diversity might be higher in areas with complex environments and large population flow. Climate type has a certain influence on the distribution of diatoms.
Beijing ; Diatoms ; Drowning ; Humans ; Rivers ; Water

OBJECTIVES: To study the annual variation of diatoms in Zhangweixin River, to provide theoretical support by using diatom examination to estimate the time and place of the corpse entering water, and to establish a diatom database. METHODS: Samples were taken from 4 sampling sites in Decheng section of Zhangweixin River for 12 consecutive months. Non-metric multi-dimensional scaling (NMDS) analysis was performed on the species and content of diatom samples. Based on the sampling site of Tianqu Road, Sprensen similarity coefficient analysis was conducted with the data of other 3 sites in Decheng section and Leling section of Zhangweixin River and Ningjin section in previous studies. RESULTS: The number of diatom species was positively correlated with diatom content. The average diatom content in different months ranged from 1 054 to 13 041/10 mL, and the species composition ranged from 8 to 16, with differences in dominant species. The similarity coefficient of diatom species within 2 km were all higher than 0.956 52, which could not be distinguished effectively. The similarity coefficients of Leling section and Ningjin section were 0.736 84 and 0.588 24 respectively, which could be effectively distinguished. CONCLUSIONS The species and content of diatom vary in different months in Zhangweixin River, and the composition of diatom species is different in different basins, which can provide reference for estimating the time and place of the corpse entering water in the river.
Cadaver ; Diatoms ; Drowning/diagnosis* ; Humans ; Rivers ; Water

OBJECTIVES: To explore the species distribution and constituent ratio of diatoms in main sections of urban district rivers where drowning occurs frequently in Chengdu. METHODS: Total 39 water samples from the sampling points of 5 rivers （Jinjiang, Jinniu, Qingyang, Wuhou and Chenghua districts） in October 2014 were collected. The diatoms smear were made and the species distribution and constituent ratio of diatoms from the water samples were analyzed using biological microscope and acquisition system of digital microscope. RESULTS: Total 21 species of diatoms were detected in main sections of urban district rivers in Chengdu. Significant differences in the dominant diatom species and proportions of the different rivers were observed, and there were different species existed in all sampling points of the upstream, midstream and downstream of the rivers. CONCLUSIONS The database of species map, species distribution and constituent ratio of diatoms in main sections of urban district rivers in Chengdu are preliminarily established, which has special meaning for the analysis and evaluation of falling location inference using diatoms test in case investigation.
China ; Cities ; Diatoms/classification* ; Drowning ; Rivers

OBJECTIVES: To explore the species, quantity and distribution of diatoms in Ningbo three-river watershed during summer and to provide scientific basis for forensic examination of drowning cases in the waters of Ningbo. METHODS: Water samples were collected in July and August of 2015. Fourteen water sampling points were selected from the Yao River, the Fenghua River and the Yong River. The morphological features of diatom species and dominant diatoms were distinguished by microscope. RESULTS: A total of 16 species of diatoms were detected in the Yao River, the Fenghua River and the Yong River. Melosira was the dominant species in the Yao River, and the quantity and richness were higher than in other rivers. The richness of Cyclotella in the Yong River was higher than in other rivers. The richness of Pinnularia and Licmophora were higher in the Fenghua River than in the Yao River and the Yong River. CONCLUSIONS The species and proportion of diatom is different in each river. Database of the species and relative composition for the diatoms in corresponding river is established, which may provide data support for forensic examination of drowning cases in Ningbo three-river watershed.
China ; Diatoms/classification* ; Drowning ; Rivers ; Seasons

Dead bodies found in the water are not all caused by drowning. The important task of forensic identification is to distinguish between entering the water before and after death, and to clarify the cause of death. In the practice of forensic identification, drowning is generally diagnosed on the basis of comprehensive considerations such as cadaveric signs, histopathological examinations, and diatom tests, with the exclusion of other causes of death. The emergence of virtopsy techniques provides new insights for the diagnosis of drowning. This paper reviews the post-mortem imaging studies of sinus and mastoid small chambers, respiratory tracts, lung tissues, gastrointestinal tracts and blood in the corpses in recent years. The value, potential of virtopsy in the diagnosis of drowning is discussed, with the prospects of its development direction.
Cadaver ; Diatoms ; Drowning ; Forensic Pathology ; Humans ; Lung

Objective To discuss the application of artificial intelligence automatic diatom identification system in practical cases, to provide reference for quantitative diatom analysis using the system and to validate the deep learning model incorporated into the system. Methods Organs from 10 corpses in water were collected and digested with diatom nitric acid; then the smears were digitally scanned using a digital slide scanner and the diatoms were tested qualitatively and quantitatively by artificial intelligence automatic diatom identification system. Results The area under the curve （AUC） of the receiver operator characteristic （ROC） curve of the deep learning model incorporated into the artificial intelligence automatic diatom identification system, reached 98.22% and the precision of diatom identification reached 92.45%. Conclusion The artificial intelligence automatic diatom identification system is able to automatically identify diatoms, and can be used as an auxiliary tool in diatom testing in practical cases, to provide reference to drowning diagnosis.
Artificial Intelligence ; Cadaver ; Diatoms ; Drowning ; Humans ; Lung

The aim of this study was to promote fucoxanthin accumulation in Phaeodactylum tricornutum by photo-fermentation through optimizing the mode of multiple nitrogen supplementation and blue light enhancement. The results showed that the mixed nitrogen source (tryptone: urea=1:1, N mol/N mol; total nitrogen concentration at 0.02 mol/L) added to the culture system by six times was the best mode in shake flasks. Two-phase culture with light adjustment was then carried out in 5 L photo-fermenter with an enhanced blue light (R: G: B=67.1:16.7:16.3) in the second phase, leading to improved cell density (1.12×10⁸ cells/mL), biomass productivity (330 mg/(d·L)), fucoxanthin content (19.62 mg/g), titer (69.71 mg/L) and productivity (6.97 mg/(d·L)). Compared with one-phase culture under red/blue (R: G: B=70.9:18.3:10.9) light and six-times nitrogen supplementation, the fucoxanthin content was significantly increased by 7.68% (P < 0.05) but the productivity did not change significantly (P > 0.05). Compared with one-phase culture under red/blue (R: G: B=70.9:18.3:10.9) light and one-time nitrogen supplementation, the content and productivity of fucoxanthin were significantly increased by 45.98% and 48.30% (P < 0.05), respectively. This study developed a two-phase culture mode with multiple nitrogen supplementation and blue light enhancement, which effectively promoted the accumulation of fucoxanthin and improved the efficiency of nitrogen source utilization, thus providing a new approach for fucoxanthin accumulation in P. tricornutum by photo-fermentation.
Nitrogen ; Light ; Xanthophylls ; Diatoms ; Dietary Supplements