Dynamic changes of microbial flora in the pickled bergamot (Citrus medica L. var. sarcodactylis) - LaoXiangHuang (LXH) during aging

Abstract

LaoXiangHuang (LXH) is a medical pickled fruit made of fresh finger citron (Citrus medica L. var. sarcodactylis) in Chaozhou, China. Aging is a process to strengthen the efficacy of Laoxianghuang (LXH), which is related to the activity of microorganisms. In this study, the changes of the microbial community of LXH within the three-years aging process were analyzed by high-throughput sequencing (HTS). According to alpha diversity results, bacterial abundance and diversity were higher than those of fungi. A total of 3 phyla and 13 bacterial genera were identified whereas 2 phyla and 4 fungal genera were identified. Meta-taxonomic of the overall bacterial communities in samples revealed that Halomonas spp. was the most abundant genus in all samples, which showed the first decresed, and then increased and decreased finally. The followed by Nitriliuptor spp., Nesterenkonia spp., Weissella spp., Notinibacter spp., Streptococcus spp., Nocardiopsis spp., Acinetobacter spp., Ralstonia spp., Lactobacillus spp. and unassigned genus. The unassigned genera (through the whole three-years fermentation period), Ustilago spp., Malassezia spp., Aspergillus spp. and Schizophyllum spp. were the predominant fungal genera. The result of PCOA and T-test analysis exhibited that the samples with different aging times have significant differences and are mainly reflected in Halomonas, unassigned bacterial genera, Nitriliruptor, Nesterenkonia, Weissella, Intestinibacter, Streptococcus and Nocardiopsis, Lactobacillus, Acinetobacter, Ralstonia, unassigned fungal genera, Ustilago spp. Malassezia spp. Aspergillus spp. and Schizophyllum spp., which may have important potential in promoting the aging process of LXH. This study helps us to understand the dynamic change of microorganisms of LXH during the aging process and provides a research basis for shortening the aging time of LXH in the future.

Keywords:
finger citrus; Citrus medica L. var. sarcodactylis; microbial flora; aging