IntroductionCandida albicans has been detected together with Streptococcus mutans in high numbers in plaque-biofilm from children with early childhood caries (ECC). The goal of this study was to examine the C. albicans carriage in children with severe early childhood caries (S-ECC) and the maternal relatedness.MethodsSubjects in this pilot cross-sectional study were recruited based on a convenient sample. DMFT(S)/dmft(s) caries and plaque scores were assessed during a comprehensive oral exam. Social-demographic and related background information was collected through a questionnaire. Saliva and plaque sample from all children and mother subjects were collected. C. albicans were isolated by BBL™ CHROMagar™ and also identified using germ tube test. S. mutans was isolated using Mitis Salivarius with Bacitracin selective medium and identified by colony morphology. Genetic relatedness was examined using restriction endonuclease analysis of the C. albicans genome using BssHII (REAG-B). Multilocus sequence typing was used to examine the clustering information of isolated C. albicans. Spot assay was performed to examine the C. albicans Caspofungin susceptibility between S-ECC children and their mothers. All statistical analyses (power analysis for sample size, Spearman’s correlation coefficient and multiple regression analyses) were implemented with SAS 9.4ResultsA total of 18 S-ECC child-mother pairs and 17 caries free child-mother pairs were enrolled in the study. Results indicated high C. albicans carriage rate in the oral cavity (saliva and plaque) of both S-ECC children and their mothers (>80%). Spearman’s correlation coefficient also indicated a significant correlation between salivary and plaque C. albicans and S. mutans carriage (p<0.01) and caries severity (p<0.05). The levels of C. albicans in the prepared saliva and plaque sample (1ml resuspension) of S-ECC children were 1.3 ± 4.5 x104 cfu/ml and 1.2 ± 3.5 x104 cfu/ml (~3-log higher vs. caries-free children). Among 18 child-mother pairs, >60% of them demonstrated identical C. albicans REAG-B pattern. C. albicans isolated from >65% of child-mother pairs demonstrated similar susceptibility to caspofungin in spot assay, while no caspofungin resistant strains were seen when compared with C. albicans wild-type strain SC5314. Interestingly, the regression analysis showed that factors such as antibiotic usage, birth weight, inhaler use, brushing frequency, and daycare attendance had no significant effect on the oral carriage of C. albicans in the S-ECC children.ConclusionsOur results reveal that both the child with S-ECC and the mother were highly infected with C. albicans, while most of the strains were genetically related, suggesting that the mother might be a source for C. albicans acquisition in the oral cavity of children affected by the disease.

No abstract

Rice blast is one of the most destructive diseases of rice and is caused by the infection with rice blast fungus, Magnaporthe oryzae. In the present study, we obtained 12 bacterial isolates from Sichuan basin neutral purplish soil. Among them, the strain named ZW-10 showed significant activity against M. oryzae. Morphological and biochemical studies, along with 16S rDNA sequencing analysis, proved that the strain belongs to Bacillus velezensis. The cell-free culture filtrate of ZW-10 inhibited the growth of M. oryzae, suggesting the presence of active enzymes and secondary metabolites. The experimental results showed that ZW-10 produced cellulase, protease, and peroxidase. The temperature experiment indicated that the secondary metabolisms of ZW-10 remained active at high temperature. In addition, this strain had good acidity resistance. As shown in leaf experiments in vitro as well as field trials, the liquid culture and the cell-free culture filtrate of ZW-10 had significant inhibitory effects on rice blast. In conclusion, ZW-10 can be used as a potential biological agent in the control of rice blast.

Biological control as a promising method to combat plant disease has gained public attention in recent years. In the present study, we isolated 12 strains resistant to Magnaporthe oryzae from western Sichuan subalpine soil. Among them, CQ07 exhibited remarkable activity against M . oryzae . The result of 16S rRNA sequence analysis revealed that CQ07 is approximately 99% similar to Bacillus australimaris . The sterilized culture filtrate of CQ07 inhibited the growth of M . oryzae , which motivated us to deduce the influence of CQ07 on the pathogenicity of M . oryzae . As shown by experimentation, sterilized culture filtrate (10 μl/ml) of CQ07 can delay and even suppress the germination of conidia and prevent the formation of appressorium in vitro and in vivo. In addition, by simulative field tests, the spraying of conidia suspension diluted with sterilized culture filtrate of CQ07 reduced infection of rice blast. To better control rice blasts, understanding the infection mechanism of M . oryzae and inhibiting the mechanism of the antagonistic strain is of great importance.