Demographic characteristics of informants

As shown in Table 1 and Fig. 2, a total of 255 informants were interviewed, including 116 who provided information on raw materials and technological processes for making CBJ and 139 who provided information on making FGRJ. A total of 116 informants, including 82 men (70.7%) and 34 women (29.3%), provided plant information for making CBJ. The ages of these informants ranged from 31 to 95 years (61.2%, age ≥ 60). The predominant education level of the informants was literate (47.4%). Of these 116 informants, 109 (93.9%) were farmers. A total of 139 informants, including 83 men (59.7%) and 56 women (40.3%), provided plant information for making FGRJ. The ages of these informants ranged from 20 to 95 years (66.9%, age ≥ 60). The predominant education level of these informants was literate (50.4%). Among these 139 informants, 119 (85.6%) were farmers. The plant knowledge mastered by the men for making jiuqu was found to be much higher than that mastered by the women. Moreover, the knowledge of making jiuqu was found to be mainly mastered by people aged 60–95 years. Overall, the informants were generally undereducated, and most of them were farmers.

Table 1 Informants’ demographic characteristicsFig. 2

Demographic characteristics of informants

According to the results of the simple linear regression, the number of JPs used for making CBJ was related to the age of the informants; with an increase in age, the number of medicinal materials mastered gradually increased (R2 = 0.1284, P < 0.0001). However, no significant correlation was found between the number of JPs for making FGRJ and the age of the informant (R2 = 0.008939, P > 0.05).

JPs diversity of the Chuanqing people

Numerous plants were used by the Chuanqing people to make jiuqu, with a total of 57 species belonging to 51 genera and 32 families (Table 2). The families, plant parts, and life forms used in the production process differed for CBJ and FGRJ (Fig. 3). Twenty-seven families were used in CBJ. Among them, the most frequently used family was Poaceae (7 species), followed by Liliaceae (3 species), and the remaining families were used only once or twice each. Thirty families were used in FGRJ. Among them, the most frequently used family was Poaceae (7 species), followed by Polygonaceae (5 species), Liliaceae and Fabaceae (3 species each), and the remaining families were used only once or twice each. Seventeen kinds of plant parts were used for CBJ, among which the whole plant was the most frequently used (19.50%), followed by the fruit (19.50%) and the root (9.80%). Eighteen kinds of plant parts were used for FGRJ, among which the whole plant was the most frequently used (22.60%), followed by the fruit (15.10%), the root (9.40%), and the aerial part (5.70%). Regarding habits, CBJ included the highest proportion of herbaceous plants (75.60%), and FGRJ was also same (69.80%).

Table 2 List of JPs used by the Chuanqing people in Nayong County, Guizhou, ChinaFig. 3

a Number of plant families used to make CBJ and FGRJ; b number of plant parts and life forms used to make CBJ and FGRJ

The China Rare and Endangered Plant Information System (http://www.iplant.cn/rep/) was searched for information on the protection of JPs, and Ephedra equisetina Bunge, Glycyrrhiza uralensis Fisch., Paris polyphylla Sm., and Lilium sulphureum Baker ex Hook.f. were all found to belong to China’s national protection level II. The Chuanqing people use rich plants to make jiuqu, which reflects their deep understanding of the natural environment and surrounding plants.

Medicinal uses for the Chuanqing people’s jiuqu

As local traditional medicine, the Chuanqing people’s jiuqu is used to treat dietary stagnation and indigestion, as it strengthens the spleen and harmonizes the stomach by eliminating food and resolving stagnation. To use the jiuqu, a small amount of water is added to soften the jiuqu before the patient takes it. It is usually taken two or three times to relieve symptoms and four or five times to cure them. No contraindications were reported for taking it. Meanwhile, a small number of people also use jiuqu to treat dizziness. In addition, jiuqu is also suitable for livestock; for example, it is used to treat diarrhea and swollen bladders in pigs.

Some JPs were also used by the Chuanqing people to treat ailments [58] (Table 3). For example, Aconitum carmichaelii Debeaux was used to treat noxious sores and restore yang for resuscitation; Aristolochia cucurbitoides C. F. Lian g was used to relieve pain; and Gleditsia sinensis Lam. was used to treat osteodynia, arthralgia, and so on.

Table 3 Medicinal uses of JPsRFC analysis of the Chuanqing people’s JPs

A total of 41 species plants were used to make CBJ, and 53 species were used to make FGRJ, with a total of 37 plants used in both species of jiuqu (Fig. 4). The results showed that the RFC values of the 41 CBJ plants ranged from 0.01 to 0.50, and nine had an RFC over 0.1: Cinnamomum cassia Presl (0.10), Zanthoxylum bungeanum Maxim. (0.11), Syzygium aromaticum (L.) Merr. & L.M.Perry (0.13), Avena sativa L. (0.13), Buddleja macrostachya Wall. ex Benth. (0.30), Fagopyrum tataricum (L.) Gaertn. (0.31), Glycyrrhiza uralensis Fisch. (0.41), Imperata cylindrica (L.) Raeusch. (0.41), and Ficus tikoua Bureau (0.50). The RFC values for the 53 FGRJ plants ranged from 0.01 to 0.54, and eight had an RFC over 0.1: Aristolochia cucurbitoides C. F. Liang (0.12), Valeriana jatamansi Jones (0.14), Fagopyrum tataricum (L.) Gaertn. (0.14), I. cylindrica (L.) Raeusch. (0.24), Avena sativa L. (0.35), Ficus tikoua Bureau (0.40), Glycyrrhiza uralensis Fisch. (0.48), and B. macrostachya Wall. ex Benth. (0.50). Fagopyrum tataricum (L.) Gaertn., I. cylindrica (L.) Raeusch., Avena sativa L., Ficus tikoua Bureau, Glycyrrhiza uralensis Fisch., and B. macrostachya Wall. ex Benth. were used in jiuqu with both high frequency and strong intersection.

Fig. 4

The Venn diagram of numbers of JPs used by Chuanqing people

Jiuqu production process used by the Chuanqing people

The Chuanqing people have a unique production process for jiuqu. Jiuqu, also locally called jiuyao, is made using the fruits of gramineous grains, such as Avena sativa L. and Eleusine coracana (L.) Gaertn., as raw materials. Jiuyaohua (B. macrostachya Benth. or Origanum vulgare L.) and yaomu (the jiuqu made last year) are used as a primer, and decoction from local plants is added as excipients (among which honey should be added for FGRJ). Then, jiuqu is cultivated under artificial control of suitable temperature and humidity.

The production processes of CBJ and FGRJ are different but related (Fig. 5). The steps for making jiuqu are as follows:

Step 1. Stir-fry the substance and the raw materials (Fagopyrum tataricum (L.) Gaertn. for CBJ; Avena sativa L. or Eleusine coracana (L.) Gaertn. for FGRJ) until they lose moisture. Remove and cool.

Step 2. Grind the fried substance and raw materials together with B. macrostachya Benth. or Origanum vulgare L.

Step 3. Boil the fresh JPs with water. Pour the liquid out and cool.

Step 4. Pour the cooled liquid into the powder from Step 2. Stir and knead into a particular shape. Then wrap with much yaomu.

Step 5. After placing the jiuqu tightly on a dustpan covered with oat grass (or replaced by an electric blanket), cover with another layer of oat grass.

Step 6. Wait for jiuqu to grow white hyphae, which signals successful production.

Step 7. Dry the jiuqu in the sun and then store.

Fig. 5

The production process for jiuqu performed by the Chuanqing people

In general, three main materials are included in the production of the Chuanqing people’s jiuqu. The first is the raw material—the fruit of Fagopyrum tataricum (L.) Gaertn., Avena sativa L., or Eleusine coracana (L.) Gaertn. The second are the herbs— jiuyaohua (B. macrostachya Benth. or Origanum vulgare L.) and yaomu. Lastly, the excipients—compound decoction and honey.

Unique plant ingredients and shape of jiuqu

During the investigation, some informants pointed out that Wuxiang (five plants with aromatic smells) and Wudu (five poisonous plants) were used in the production of jiuqu (Fig. 6). Wuxiang plants: Foeniculum vulgare Mill., V. jatamansi Jones, Aristolochia cucurbitoides C. F. Liang, and two other plants (no original plants were collected). Regarding the original Wuxiang plants, there are differences between different regions. For example, Foeniculum vulgare Mill. was replaced by Pogostemon cablin (Blanco) Benth. or Syzygium aromaticum (L.) Merr. & L.M.Perry. Wudu plants: Paris polyphylla Sm., Arisaema erubescens (Wall.) Schott, Aconitum carmichaelii Debeaux, Achillea wilsoniana (Heimerl) Hand.-Mazz., and Lilium brownii F. E. Brown ex Miellez (or L. sulphureum Baker ex Hook.f.). Wudu plants are often used in the production of CBJ but are rarely used or used in small doses for FGRJ production.

Fig. 6

Some Wuxiang and Wudu plants in the survey area. a–c The original Wuxiang plants; d–h the original Wudu plants

In addition to unique plants, the jiuqu shape is also exceptional. For making CBJ, jiuqu has a variety of shapes, from flat cylindrical to spherical. However, for FGRJ, they are peanut shaped in all regions (Fig. 5).

Analysis of microbial diversity in jiuqu samples

Based on ITS1 and 16S rRNA sequencing, the numbers of effective sequences in the four samples ranged from 10,786 to 11,333 and from 9948 to 12,767 for bacteria and fungi, respectively. The OTU numbers for bacteria and fungi in each sample are shown in Table 4. The rarefaction curves were constructed with sequence and species numbers to verify whether the sequencing data were sufficient to reflect the species diversity in the four samples (Fig. 7). This suggested that the sequencing depth was adequate to represent the microbial structure and diversity of the samples. The determination of α-diversity was conducted using Chao1 and Shannon indices and coverage values (Table 4). The Chao1 indices measured the richness of species, while the Shannon indices represented species diversity. The coverage value reflects the probability of detected sequences. Table 4 shows that the Chao1 index in sample YQ1 reached 17.0000 and 20.0000 for the bacteria and fungi communities, respectively, indicating the highest species abundance. The Shannon index for samples YQ3 and YQ1 has reached 1.7123 and 2.1812 for the bacteria and fungi communities, respectively, indicating the highest species evenness.

Table 4 OTUs and α-diversity indices of jiuqu samplesFig. 7

The rarefaction curves of four samples

The sequence coverage of the four samples was beyond 99%, indicating that more species were detected and the sequencing results could truly reflect the species abundance and diversity of the sample.

Diversity profiles of bacteria and fungi communities

Dissimilar bacterial and fungi communities were found at the species level for the four types of samples (Fig. 8). Gluconobacter japonicus was the dominant bacterial community in YQ1 and YQ4, accounting for 53.7% and 74.7%, respectively, followed by Weissella confusa and Enterobacter muelleri in YQ1 and YQ4, which accounted for 42.1% and 15.6%, respectively. Pediococcus pentosaceus was the dominant bacterial community in YQ2 and YQ3, accounting for 66.5% and 45.2%, respectively, followed by Leuconostoc pseudomesenteroides and Enterobacter muelleri in YQ2 and Enterococcus faecium and Enterobacter muelleri in YQ3, which accounted for 10.1%, 9.7%, 38.1%, and 11.3%, respectively.

Fig. 8

a Bacteria microbial community structure; b fungi microbial community structure; c cluster heatmap of bacteria species based on the microbial community profiles; d cluster heatmap of fungi species based on the microbial community profiles

In addition to unidentified fungal species, Rhizopus oryzae was also the dominant fungus in YQ1, YQ2, YQ3, and YQ4, at 44.0%, 29.0%, 29.0%, and 22.0%, respectively. Hyphopichia burtonii was only identified in YQ1 and YQ4, accounting for 2.3% and 3.0%, respectively. Moreover, Aspergillus cibarius and Aspergillus vitricola were found at 11.7% and 3.0% in YQ1, respectively.

Figure 8 shows the heatmap of clustering for species abundance based on the microbial community profiles. In general, many differences were found in relative species abundance among the four jiuqu samples. The species varied among the samples. For bacterial communities, YQ4 had a high relative abundance of Lactobacillus plantarum, Staphylococcus saprophyticus, Acetobacter orientalis, Gluconobacter japonicus, and Enterobacter muelleri.; YQ2 had a high relative abundance of Pedicoccus pentosaceus, L. lactis, and Pantoea agglomerans; YQ1 had a high relative abundance of Ralstonia pickettii, L. curvatus, Weissella confusa, Porphyrommonas asaccharolytica, uncultured bacterium g Candidatus Xiphinematobacter, and uncultured bacterium g Candidatus Koribacter; and YQ3 had a high relative abundance of Massilia suwonenis, Enterococcus faecium, Bacillus pumilus, Massilia putida, Sphingomonas aerolata, Rosenbergiella epipactidis, and Campylobacter ureolyticus. For fungal communities, YQ3 had a high relative abundance of Aspergillus subflavus and Rhizopus microspores; YQ2 had a high relative abundance of Cladosporium austroafricanum; YQ4 had a high relative abundance of Meyerozyma smithsonii, Candida parapsilosis, Wickerhamomyces anomalus, H. burtonii, and Penicillium freii; and YQ1 had a high relative abundance of Fusarium guttiforme, Aspergillus vitricola, Penicillium hetheringtonii, Xerochrysium dermatitidis, Pichia fermentans, Aspergillus cibarius, Wallemia canadensis, Aspergillus foveolatus, Penicillium steckii, Mucor circinelloides, and Rhizopus oryzae.