In this study, 149 strains of microorganisms were isolated from 24 samples of maternal and infant clothing by culturable technology, including 102 strains of bacteria which covered 16 genera, and the most frequently isolated bacteria at the genus level were Staphylococcus, Micrococcus, Moraxella, Pseudomonas, and Bacillus. Among them, Staphylococcus, Micrococcus, Moraxella were the bacterial genus with the largest number of isolates in all samples, and distributed in most clothing samples. The results are shown in Figs. 3 and 4.
A total of 47 strains of fungi were isolated, covering 24 genera. At the genus level, the most frequently isolated fungi were Cladosporium, Alteraria, Rhodotorula, Aspergillus, and Penicillium. Among them, Cladosporium, Alteraria and Rhodotorula were the fungus genus with the largest number of isolates in all samples, and distributed in most of the clothing samples. The results are shown in Figs. 5 and 6.
Staphylococcus was the most isolated bacteria in all the samples of maternal and infant clothing samples, and distributed in a plurality of clothing sample. 39 strains of Staphylococcus were isolated from 16 samples, accounting for 38.2% of the total isolated strains, belonging to 6 species. They were as follows: Staphylococcus hominis, Staphylococcus epidermidis, Staphylococcus aureus, Staphylococcus xylosus, Staphylococcus haemolyticcus and Staphylococcus caspitis, which were often isolated from human skin. They mainly exist in human nostrils, armpits, groins and other parts[7]. Some strains of this genus are conditionally pathogenic and can cause diseases by producing pathogenic factors such as plasma coagulase and hemolysin [8].
In addition, Moraxella, Micrococcus and Pseudomonas were isolated. Among them, Moraxella is often isolated from humans and other warm-blooded animals. The key isolate, Moraxella osloensis, is widely distributed in human skin and human-related environments, infected with this bacterium may lead to bacteremia in patients. It had been reported that the "wet rag-like" odor of clothes after drying may be due to Moraxella Osloensis. It was caused by the metabolism of osloensis to produce 4-methyl-3-hexenoic acid, which has potential odor-causing characteristics[9]. Micrococcus is often isolated from human skin, natural environment and food. Key isolate of Micrococcus luteus, is widely distributed in mammalian skin. And is mainly obtained by separating the skin of the head, the leg and the arm of a human body. The strain metabolizes cadaverine through lysine decarboxylase to make human body and clothes generate peculiar smell. And Micrococcus luteus is a conditional pathogenic bacterium, may cause bacteremia, pneumonia, septic arthritis, and meningitis [10]. The genus Pseudomonas is widely isolated from natural environments such as water, soil and plant roots. It was also separated from terylene, flax and wool fabrics. Some strains of this genus have both animal pathogenicity and plant pathogenicity. Some strains can cause corneal infection, respiratory tract infection and polycystic fibrosis through virulence factors and quorum sensing.
Two strains of Rothia were isolated in this study, which were often isolated from human throat and oral cavity [11]. At the same time, it is also a common intestinal bacteria in infants, which has low virulence to infants, and has been reported to be related to infant health.
In that cloth sample of the mother and infant population, Cladosporium, Rhodotorula, and Alternaria were that most isolate in all sampled genus of numerous fungi. Seven Cladosporium strains were isolated from seven clothing samples, accounting for 14.9%.These fungi are widely distributed in soil, some animal feces, vegetables, rotten wood, birds'nests and rotten fruits. It is a common environmental microorganism and has a high abundance in pet skin. This bacterium belongs to the third class of opportunistic pathogens, and the spores infected with this bacterium may be sinusitis, fungal allergy and so on. At the same time, cellulose can be degraded by cellulose hydrolase, resulting in the deterioration of cotton, and keratin can be decomposed, resulting in the deterioration of wool. Some strains can produce eumelanin and melanophil, which may lead to clothing contamination. Six strains of Rhodotorula were isolated from six clothes samples, accounting for 12.8% of the total isolated strains. These fungi are widely distributed in the natural environment of animals and plants, rivers, lakes and oceans. A few species are opportunistic pathogens. Six Alternaria strains were isolated from six clothes samples, accounting for 12.8% of the total number of isolates. This kind of bacteria is widely distributed in water environment, soil and air, and is the resident bacteria of human skin. Some strains of the genus have both animal and plant pathogenicity, which can cause tinea, asthma and allergy in humans. Infected plants can cause disease spots on crops, cash crops and other plants, which can cause serious economic losses. At the same time, the strain has cellulose degradation ability, can degrade cotton fabrics, and has potential fabric damage.
A total of 3155 OTUs were sequenced from 24 samples by high-throughput sequencing analysis using culture-independent technology, including 1490 OTUs in bacteria. Fungi 1665 OUT.
A total of 1490 OTUs were obtained by high-throughput sequencing of 16s rRNA genes from 24 samples. At the phylum level, Proteobacteria was the dominant bacterial phylum in the clothing samples, with a relative abundance of 60.7%. Firmicutes, Actinobacteria, Bacteroidetes and Cyanobacteria, as shown in Fig. 7A. Enhydrobacter and Acinetobacter were that dominant bacteria in the clot samples, the relative abundances were 30.92% and 15.91%, respectively, as shown in Fig. 7B.
Based on the results of OTU cluster analysis, the Alpha diversity index of different groups of samples was calculated. The influence of season, city, wearer and other factors on the bacterial community structure of clothing was analyzed. The results are shown in Table 4. The statistical results show that factors such as season, wearer and city had significant effects on the bacterial community structure of clothing.
Table 4
Microbial diversity index of clothing for mothers and infants grouped by different factors
Grouping | Category | Quantity | The Chao index | The Shannon index |
Average value | p-value | Average value | p-value |
Season | Spring | 12 | 405 | 0.34736 | 1.99 | 0.9774 |
Summer | 12 | 378 | 1.96 |
The wearer | Baby | 12 | 406 | 0.37769 | 1.96 | 0.9323 |
Mother | 12 | 315 | 2.04 |
City | Hangzhou | 12 | 333 | 0.08873 | 1.59 | 0.05966 |
Nanjing | 12 | 490 | 2.14 |
High-throughput sequencing of ITS rRNA genes was performed on 24 samples, and 2016 OTUs were obtained. At the phylum level, Bsidiomycota and Ascomycota are the dominant fungal phyla in clothing samples. The relative abundances are 66.97% and 32.50%, respectively, as shown in Fig. 8A. In order to further clarify the species composition of fungal community, the fungal composition of clothing samples from mothers and infants was analyzed at the subordinate level. As shown in Fig. 8B. Malassezia was the dominant fungi in the clothing samples, with a relative abundance of 39.08%. The relative abundance of Aspergillus, Cladosporium and Rhodotorula was more than 5%, which was 6.94%, 6.19% and 6.01% respectively.
Based on the results of OTU cluster analysis, the Alpha diversity index of different groups of samples was calculated. The influence of season, city, wearer and other factors on fungal community structure of clothing was analyzed. The results are shown in Table 5. The statistical results show that factors such as season, wearer and city had significant effects on the fungal community structure of clothing.
Table 5
Microbial diversity index of clothing for mothers and infants grouped by different factors
Grouping | Category | Quantity | The Chao index | The Shannon index |
Average value | p-value | Average value | p-value |
Season | Spring | 12 | 236 | 0.236 | 3.41 | 0.589 |
Summer | 12 | 203 | 3.58 |
The wearer | Mother | 12 | 179 | 0.068 | 3.42 | 0.842 |
Baby | 12 | 239 | 3.48 |
City | Hangzhou | 12 | 212 | 0.794 | 3.51 | 0.755 |
Nanjing | 12 | 221 | 3.58 |