Approximately 381 million tons of plastic are produced globally every year, and the majority of it ends up as pollutants. In the environment, plastic waste is fragmented into microplastic particles less than 5 mm in size; owing to their small size, durability, and abundance, they can easily be dispersed, incorporated into the food chains, and enter the human body. The extent of microplastic exposure in the human body has become a major concern in many countries, including in Indonesia, the second largest plastic waste contributor in the world. Here, we report the detection of microplastics in human stools collected from a fisherman community in the coastal area of Surabaya, Indonesia. Microplastics were found in more than 50% of samples analyzed with a concentration ranging from 3.33 to 13.99 µg of microplastic per gram of feces (µg/g). HDPE was observed as the most prevalent type of microplastic, with an average concentration of 9.195 µg/g in positive samples. Different types of microplastics were also detected in seafood, staple foods, drinking water, table salts, and toothpaste, which were regularly used and consumed by the study participants. Results from this preliminary study indicate widespread contamination of microplastic in the human body and in consumables associated with the coastal populations of Indonesia.

A subgroup of biogenic amines, the so-called trace amines (TAs), are produced by mammals and bacteria and can act as neuromodulators. In the genus Staphylococcus, certain species are capable of producing TAs through the activity of staphylococcal aromatic amino acid decarboxylase (SadA). SadA decarboxylates aromatic amino acids to produce TAs, as well as dihydroxy phenylalanine and 5-hydroxytryptophan to thus produce the neurotransmitters dopamine and serotonin. SadA-expressing staphylococci were prevalent in the gut of most probands, where they are part of the human intestinal microflora. Furthermore, sadA-expressing staphylococci showed increased adherence to HT-29 cells and 2- to 3-fold increased internalization. Internalization and adherence was also increased in a sadA mutant in the presence of tryptamine. The α2-adrenergic receptor is required for enhanced adherence and internalization. Thus, staphylococci in the gut might contribute to gut activity and intestinal colonization.

Plastic is one of the most abundant pollutants in the environment. As a result of natural physical processes, large plastic waste is degraded into microsized particles (<5 mm) called microplastics. Because of their size, abundance, and durability, microplastics are widely distributed in the environment, contaminating food and water intended for human consumption. The extent of microplastic contamination in the human body is still unclear because there are few studies concerning microplastic contamination in human specimens and, in most studies, data were collected from city dwellers. Despite having the fourth largest population and being the fourth largest plastic waste producer in the world and second largest plastic polluter in the ocean, there are currently no data with respect to microplastic exposure for the Indonesian population. Several studies have reported on microplastic contamination in seafood and freshwater organisms from Indonesia, and it is likely that microplastics have contaminated the gastrointestinal tracts of Indonesians. Using Raman spectroscopy, we detected microplastic contamination in 7 out of 11 analyzed stool samples collected from a farming community in the highland village of Pacet, East Java, Indonesia. Polypropylene (PP) was the most abundant and prevalent type of microplastic observed, and it was found in four of the positive samples with an average concentration of 10.19 microgram per gram of feces (μg/g). Microplastics were also detected at high concentrations in tempeh (soybean cake, a staple protein source for Indonesians), table salts, and toothpaste, which were regularly consumed and used by the study participants. PP was particularly high in table salts (2.6 μg/g) and toothpaste (15.42 μg/g), suggesting that these products might contribute to the gastrointestinal contamination in the studied population. This pilot study indicated microplastic contamination in the rural Indonesian population and in their daily consumables, demonstrating the far-reaching extent of microplastic pollution beyond urban areas.

Release of cytoplasmic proteins into the supernatant occurs both in bacteria and eukaryotes. Because the underlying mechanism remains unclear, the excretion of cytoplasmic proteins (ECP) has been referred to as "non-classical protein secretion." We show that none of the known specific protein transport systems of Gram-positive bacteria are involved in ECP. However, the expression of the cationic and amphipathic α-type phenol-soluble modulins (PSMs), particularly of PSMα2, significantly increase ECP, while PSMβ peptides or δ-toxin have no effect on ECP. Because psm expression is strictly controlled by the accessory gene regulator (agr), ECP is also reduced in agr-negative mutants. PSMα peptides damage the cytoplasmic membrane, as indicated by the release of not only CPs but also lipids, nucleic acids, and ATP. Thus, our results show that in Staphylococcus aureus, PSMα peptides non-specifically boost the translocation of CPs by their membrane-damaging activity.

Excretion of cytoplasmic proteins in pro- and eukaryotes, also referred to as 'non-classical protein export', is a well-known phenomenon. However, comparatively little is known about the role of the excreted proteins relating to pathogenicity. Here the impact of two excreted glycolytic enzymes, aldolase (FbaA) and glyceraldehyde 3-phosphat dehydrogenase (GapDH) on pathogenicity was investigated in Staphylococcus aureus. Both enzymes bound to certain host matrix proteins and enhanced adherence of the bacterial cells to host cells but caused a decrease of host cell invasion. FbaA and GapDH also bound to the cell surface of staphylococcal cells by interaction with the major autolysin Atl that is involved in host cell internalization. Surprisingly, FbaA showed a high cytotoxicity to both MM6 and HaCaT cells, while GapDH was only cytotoxic for MM6 cells. Finally, the contribution of external FbaA and GapDH to S. aureus pathogenicity was confirmed in an insect infection model.