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Composition of norfloxacin-resistant bacteria and isolation of norfloxacin-degrading bacteria in subtropical aquaculture ponds in China

Mao Lutian, Chen Lifen, Wang Xirui, Xu Zhongbao, Ouyang Hui, Huang Biyou, Zhou Libin

Archives of Environmental Protection

2022

Vol. 48, no. 4

95--101

To analyze the composition of norfloxacin-resistant bacteria and norfloxacin-degrading bacteria in pond water and sediment in subtropical China, the composition of antibiotic resistant bacteria in pond water and sediment enriched with norfloxacin-containing medium was analyzed by high-throughput sequencing. Sediment and water samples were collected from 3 fish ponds in subtropical China, and domesticated with norfloxacin, subsequently norfloxacin-resistant bacteria through high-throughput sequencing of 16S rDNA, and isolated norfloxacin--degrading bacteria. Our results showed that the pond sediment and water contain a variety of norfloxacin-resistant bacteria, mainly from Proteobacteria, Bacteroidetes, Actinobacteria, Firmicutes, and Chloroflexi. Moreover, we isolated two norfloxacin-degrading bacteria (NorXu-2 and NorXu-3). The norfloxacin-degrading rate by NorXu-2 and NorXu-3 in the culture mediums with 200 μg/mL was the highest, which was up to 49.71% and 35.79%, respectively. When the norfloxacin concentration was 200 μg/mL, NorXu-2 and NorXu-3 had the best norfloxacin- -degrading effect at pH of 6, and the degradation rates were 53.64% and 45.54%, respectively. Moreover, NorXu-3 exhibited a good tolerance to high NaCl concentration. These results not only provided basic data for the follow-up study of the molecular mechanism of antimicrobial microbial degradation, but also provided potential norfloxacin degrading bacteria for norfloxacin removal and bioremediation in aquaculture environment.

Phosphorus forms in the sediment of seagrass meadows affected mainly by fungi rather than bacteria : a preliminary study based on 31P-NMR and high-throughput sequencing

Zhao Muqiu, Wang Hui, Wang Shuai, Han Qiuying, Shi Yunfeng

Oceanological and Hydrobiological Studies

2020

Vol. 49, No. 4

408--420

Microorganisms play an important role in the circulation of phosphorus (P) in the sediment of coastal wetland ecosystems. In this study, solution 31P nuclear magnetic resonance (NMR) was used to determine different forms of P in the sediments of four different seagrass meadows and a bare tidal flat, while high-throughput 16S and ITS rRNA gene sequencing was used to determine the microbial community composition. The solution 31P-NMR spectra revealed six forms of the P compounds detected by the NaOH-EDTA extraction of sediments, where Ortho-P was the most dominant P compound, followed by Mono-P. The Po compounds were more varied in the seagrass meadow sediments and more abundant compared to the bare tidal flat. Bacterial communities in the sediments collected from E. acoroides and fungal communities in the bare tidal flat were relatively different from those at the other sites. The relative abundance of P-cycling-related fungi belonging to the phylum Ascomycota was 26.20% and was much higher than that of bacteria (only 0.29%) belonging to the class Bacilli. Mono-P was the major factor determining the distribution of P-cycling-related fungi and negatively correlated with the relative abundance of Aspergillus and Trichoderma. We believe that fungi can affect P forms in the sediment of seagrass meadows more than bacteria.

Bacterial Community of Neutral Mine Drainage of Elizabeth’s Shaft (Slovinky, Slovakia)

Kiskova Jana, Perhacova Zuzana, Vlcko Ladislav, Sedlakova-Kadukova Jana, Kvasnova Simona, Pristas Peter

Inżynieria Mineralna

2019

R. 21, nr 1

89--94

Neutral mine drainage is the less frequent subject of the interest than acid mine drainage but it can have adverse environmental effects caused mainly by precipitation of dissolved Fe. The aim of the study was to characterize the composition of bacterial population in environment with high concentration of iron and sulfur compounds represented by neutral mine drainage water of Elizabeth’s shaft, Slovinky (Slovakia). The pH value of drainage water decreased from 7.1 to 6.5 during the years 2008–2014. Direct microscopic observations, cultivation methods, and 454 pyrosequencing of the 16S rRNA gene amplicons were used to examine the bacterial population. Microscopic observations identified iron–oxidizing Proteobacteria of the genera Gallionella and Leptothrix which occurrence was not changed during the years 2008–2014. Using 454 pyrosequencing, there were identified members of 204 bacterial genera that belonged to 25 phyla. Proteobacteria (69.55%), followed by Chloroflexi (10.31%) and Actinobacteria (4.24%) dominated the bacterial community. Genera Azotobacter (24.52%) and Pseudomonas (14.15%), followed by iron–oxidizing Proteobacteria Dechloromonas (11%) and Methyloversatilis (8.53%) were most abundant within bacterial community. Typical sulfur bacteria were detected with lower frequency, e.g., Desulfobacteraceae (0.25%), Desulfovibrionaceae (0.16%), or Desulfobulbaceae (0.11%). Our data indicate that the composition of bacterial community of the Elizabeth’s shaft drainage water reflects observed neutral pH, high level of iron and sulfur ions in this aquatic habitat.

Odciek kopalniany o odczynie obojętnym jest rzadszym przedmiotem zainteresowania niż odciek kopalniany kwaśny, ale może mieć niekorzystne skutki środowiskowe spowodowane głównie przez wytrącanie rozpuszczonego Fe. Celem artykułu jest scharakteryzowanie składu bakterii w środowisku o wysokim stężeniu związków żelaza i siarki reprezentowanych przez obojętne wody drenażowe kopalni szybu Elizabeth, Slovinky (Słowacja). Wartość pH wody drenażowej spadła z 7,1 do 6,5 w latach 2008–2014. Bezpośrednie obserwacje mikroskopowe, metody hodowli i pirosekwencjonowanie amplikonów genu 16S rRNA wykorzystano do zbadania populacji bakterii. Obserwacje mikroskopowe zidentyfikowały proteobakterie utleniające żelazo z rodzajów Gallionella i Leptothrix, których występowanie nie uległo zmianie w latach 2008–2014. Przy użyciu pirosekwencjonowania 454 zidentyfikowano 204 rodzajów bakterii należących do 25 typów. Proteobakterie (69,55%), a następnie Chloroflexi (10,31%) i aktynobakte rie (4,24%) zdominowały społeczność bakteryjną. Rodzaje Azotobacter (24,52%) i Pseudomonas (14,15%), a następnie proeto-bakterie żelazo utleniające Dechloromonas (11%) i Methyloversatilis (8,53%) były najbardziej rozpowszechnione w społeczności bakteryjnej. Typowe bakterie siarkowe wykryto z mniejszą częstotliwością, np. Desulfobacteraceae (0,25%), Desulfovibrionaceae (0,16%) lub Desulfobulbaceae (0,11%). Uzyskane dane wskazują, że skład flory bakteryjnej wody drenażowej szybu Elżbieta odzwierciedla obserwowane neutralne pH, wysoki poziom zawartości jonów żelaza i siarki w środowisku wodnym.