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M., Grunwald, S. and Sick- man, J. O., Soil Sci. Soc. Am. J. , 2009, 73, 176–184. 29. Ladoni, M., Bahrami, H. A., Alavipanah, S. K. and Norouzi, A. A., Precis. Agric., 2010, 11, 82–89. 30. Baumgardner, M. F., Kristof, S., Johann- sen, C. J. and Zachary, A., Proc. Indiana Acad. Sci., 1970, 79, 413–422. 31. Galvao, L. S. and Vitorello, I., Int. J. Remote Sensing, 1998, 19, 1969–1979. ACKNOWLEDGEMENTS. This study was supported by the National Natural Science Foundation of China (No. 41201215 and No. 41301505). The map of soil type used in sampling was provided by Data Sharing Infra- structure of Earth System Science (www.geodata.cn ). We thank Jingchen Zheng for help during the field work. We also thank Changqiao Hong, Junfeng Xiong, Minmin Huang, Yuting Tao, Yongwei Gan, Jiangjie Jia and Cheng Lv for sample processing and spectral measurements. Received 25 June 2015; revised accepted 13 March 2018 GUANGHUI ZHENG* CAIXIA JIAO GANG SHANG FENFANG LIN School of Geographical Sciences, Nanjing University of Information Science and Technology, Nanjing, China *For correspondence. e-mail: zgh@nuist.edu.cn Emergence of multidrug-resistant Raoultella ornithinolytica associated with Indian major carp Raoultella ornithinolyitca is a Gram- negative, non-motile bacillus belonging to the family Enterobacteriaceae and has been associated with hospital-acquired clinical cases. The pathogenic potential of R. ornithinolytica isolates in human disease has become increasingly impor- tant 1 . The well-known factors involved in pathogenicity of R. ornithinolytica are its ability to adhere to human tissue, to convert histidine to histamine and to form biofilms in urinary catheters and other surgical equipment. The clinical presentations of infections include bacte- raemia 2,3 , enteric fever 4 , diabetic foot 5 , urinary tract infection, billiary tract infection, community and hospital- acquired pneumonia, pleural effusion, osteomyelitis, meningitis, cerebral abscess, pericarditis, conjunctivitis, otitis and skin infections 6 . A high rate of hospital- acquired infections has been reported in patients with immunodeficiency and those who have undergone invasive pro- cedures, e.g. mechanical ventilation, uri- nary catheters and post-urethral trauma 1 . This bacterium, along with closely re- lated species R. planticola, has been shown to be the causative agent of his- tamine toxicity from fish (also known as scombroid syndrome), but is frequently misidentified as Klebsiella pneumoniae. Histamine toxicity results from the ex- pression of histidine decarboxylase, which enables the bacterium to convert histidine, and produces symptoms that include flushing, pruritus, headache and abdominal cramping 7 . Over the past decade, R. ornithinolytica has emerged as an infrequent, but important causative agent of human infections 8 . To the best of our knowledge, few cases of R. ornithinolytica human infection have been reported worldwide, linking this pathogen to bacteraemia, sepsis, soft tis- sue and other infections 9 . The bacterium has also been isolated from human diges- tive organs 1 . Indian major carp (IMC), commonly known as rohu, is one of the most pre- ferred aquaculture fish species among the carps in India and commands a higher market price. However, with the increase in aquaculture production of rohu, occur- rence of diseases proves to be significant setback for successful aquaculture by spoilage during cultivation, preservation and trading problems caused by patho- genic bacteria. The most common bacte- rial pathogens in IMC found in this region are Aeromonas hydrophila, A. liquefaciens, A. sorbia, A. veronii, Ed- wardsiella tarda, Providencia vermicola, Acinetobacter baumanni, Pseudomonas fluorescence, Shigella sp. and Chondro- coccus columnaris. A. hydrophila ac- counts for the most common pathogen in IMC and has zoonotic significance 10 . The aquatic environment harbours