Understanding gut lactic acid bacteria (LAB) in healthy hosts is an important first step in selecting potential probiotic species. To understand the dynamics of LAB in healthy goats, a cohort of thirty-seven healthy new-born goat kids was studied over a ten-month period. Total LAB was quantified using SYBR green qPCR. Seven hundred LAB isolates were characterized using microscopy, M13 RAPD genotyping and 16S rDNA sequencing. The highest and lowest LAB counts were detected at one week and ten months of age, respectively. Diverse LAB species were detected, whose identity and prevalence varied with age. The main isolates belonged to Limosilactobacillus reuteri, Limosilactibacillus fermentum, Lactobacillus johnsonni, Ligilactobacillus murinus, Ligilactobacillus salivarius, Limosilactobacillus mucosae, Lactiplantibacillus plantarum, Ligilactobacillus agilis, Lactobacillus acidophilus/amyolovolus, Pediococcus spp. and Enterococcus spp. Uniquely, L. reuteri and Pediococcus spp. were most common in pre- and peri-weaned goats, while Lactobacillus mucosae and Enterococcus spp. were predominant in goats one month and older. Based on RAPD genotyping, L. reuteri had the highest genotypic diversity, with age being a factor on the genotypes detected. This data may be relevant in the selection of age-specific probiotics for goats. The findings may also have broader implications by highlighting age as a factor for consideration in probiotic bacteria selection in other animal hosts.

The authors have requested that this preprint be removed from Research Square.

The authors have requested that this preprint be removed from Research Square.

The emergence of multidrug-resistant microbes presents a serious public health threat that requires new antimicrobial methods. A potential solution to combat resistance involves using metal nanoparticles that possess improved biological characteristics. The researchers have synthesized gold nanoparticles (Au-NPs) using gamma irradiation of Polyacrylamide (PAM) at 5, 10, and 15 kGy doses and through Au/chitosan nanocomposite production methods. They have also assessed the antimicrobial and anticancer functions of the produced nanomaterials by testing them on various microorganisms and cancer cell lines. Gold nanoparticles exhibited strong antibacterial effects against multiple Gram-positive bacterial strains, including Bacillus subtilis, Micrococcus luteus, Staphylococcus epidermidis, Staphylococcus aureus, and Streptococcus mutans, as well as methicillin-resistant Staphylococcus aureus (MRSA). Escherichia coli showed a significant inhibition zone of 23 mm, and Salmonella spp. showed similar inhibition. The inhibition zone for Klebsiella pneumoniae ATCC 13883 revealed resistance. The Au-NPs/chitosan composite showed moderate antifungal effectiveness against Syncephalis racemosum and Aspergillus niger alongside Candida albicans and several other tested fungi. Au-NPs showed cytotoxicity to breast MCF-7 cells, as well as liver HepG-2 cells and colon HCT-116 cells. The combination of Au-NPs with chitosan demonstrated limited effectiveness in countering hepatitis A virus (HAV-10) and herpes simplex virus type 1 (HSV-1). The combination of gamma-irradiated Au-NPs with biopolymers like chitosan demonstrates significant promise in antimicrobial and anticancer biomedical applications.