Applied Microbiology

Surfactants are harmful, persistent pollutants that are often found in contaminated soils, wastewater, and industrial effluents in complex mixes. Due to their chemical diversity and persistence, they present a bioremediation challenge. Using long-read shotgun metagenomics, 16S rRNA amplicon sequencing, PICRUSt2 functional prediction, and physicochemical proxies (total organic carbon, dissolved oxygen, chemical oxygen demand, foaming activity, etc.), this study investigated the aerobic biodegradation of SDS, SLS, rhamnolipids, Triton X-100, and CTAB (individually/mixed, 4% w/v) by microbial consortia enriched from oil-contaminated soil for 14 days. Pseudomonadota was dominant (85–90%), with Pseudomonas (60%) driving SLS and SDS degradation, while Paraburkholderia and Bordetella were dominant in recalcitrant surfactant degradation. Among the surfactants, SLS, rhamnolipids, and the combination of all surfactants demonstrated higher degradation by virtue of total organic carbon reductions of 50%, 56%, and 50%, respectively, and a foaming activity decline of 45–64%. The combination of surfactants with CTAB showed a 21% reduction in TOC, most likely due to CTAB’s known bactericidal effects. PICRUSt2 showed differential enrichment in alkyl oxidation, sulfate ester hydrolysis, aromatic ring cleavage, and fatty acid/sulfur genes and pathways. This study establishes inexpensive, scalable proxy indicators for monitoring surfactant bioremediation when direct metabolite analysis is impractical.

Potato (Solanum tuberosum L.) is a key staple crop in the Peruvian Andes, but its productivity is threatened by fungal pathogens such as Rhizoctonia solani and Alternaria alternata. In this study, 71 native bacterial strains (39 from phyllosphere and 32 from rhizosphere) were isolated from potato plants across five agroecological zones of Peru and characterized for their plant growth-promoting (PGPR) and antagonistic traits. Actinomycetes demonstrated broader enzymatic profiles, with 2ACPP4 and 2ACPP8 showing high proteolytic (68.4%, 63.4%), lipolytic (59.5%, 60.6%), chitinolytic (32.7%, 35.5%) and amylolytic activity (76.3%, 71.5%). Strain 5ACPP5 (Streptomyces decoyicus) produced 42.8% chitinase and solubilized both dicalcium (120.6%) and tricalcium phosphate (122.3%). The highest IAA production was recorded in Bacillus strain 2BPP8 (95.4 µg/mL), while 5ACPP6 was the highest among Actinomycetes (83.4 µg/mL). Siderophore production was highest in 5ACPP5 (412.4%) and 2ACPP4 (406.8%). In vitro antagonism assays showed that 5ACPP5 inhibited R. solani and A. alternata by 86.4% and 68.9%, respectively, while Bacillus strain BPP4 reached 51.0% inhibition against A. alternata. In greenhouse trials, strain 4BPP8 significantly increased fresh tuber weight (11.91 g), while 5ACPP5 enhanced root biomass and reduced stem canker severity. Molecular identification confirmed BPP4 as Bacillus halotolerans and 5ACPP5 as Streptomyces decoyicus. These strains represent promising candidates for the development of bioinoculants for sustainable potato cultivation in Andean systems.

Companilactobacillus farciminis KUJ 25-S was isolated from fermented fish and identified using 16S rRNA gene sequencing with 30.0 g/L of L-LA (L-lactic acid), with 97% LA per sum of DL-LA. The characteristics of LA and its stereoisomers were confirmed using TLC, chiral-HPLC, and enzymatic techniques. Based on various conditions using liquid MRS broth (static condition, glucose 10%, NaCl 5%, 37 °C for 48 h), the highest growth and LA formation of the culture were at a low temperature (25 °C) and decreased at 37, 45, and 55 °C, respectively. The broth could grow and produce acid at an initial pH in the range 4–11, with a low initial pH of 4 promoting the highest LA formation. LA formation and growth were inversely proportional to the NaCl concentration in the 0.5–30% range. High glucose concentrations suppressed LA formation. The growth-promotion effect varied with glucose concentration (5–40%), with the optimum concentration for LA production being 20% glucose. On the other hand, if used in microoxic conditions, the absence of NaCl was more favorable to acidification than the addition of NaCl (5% NaCl). C. farciminis KUJ 25-S was proposed as a suitable method to produce L-LA based on using the appropriate line for further industrial use.