A multidisciplinary approach to the comparison of three contrasting treatments on both lampenflora community and underlying rock surface.

Removing lampenflora, phototrophic organisms developing on rock surfaces in tourist cavities due to the artificial lighting, is a challenge for sustainable and appropriate long-term management of caves. Photosynthetic-based biofilms usually cause rock biodeterioration and an ecological imbalance in cave ecosystems. In this work, a detailed investigation of the effects of the 3 most commonly used lampenflora cleaning operations (NaClO, H2O2 and UVC) was carried out in Pertosa-Auletta Cave (Italy). The application of NaClO showed good disinfection capability over extended periods of time without causing any appreciable rock deterioration. The H2O2 treatment showed to be corrosive for the rock surfaces covered with vermiculation deposits. The chemical alteration of organic and inorganic compounds by H2O2 did not remove biomass, favoring biofilm recovery after three months of treatment. Both NaClO and H2O2 treatments were effective at removing photoautotrophs, although the bacterial phyla Proteobacteria and Bacteroidetes as well as Apicomplexa and Cercozoa among the Eukaryotes, were found to be resistant to these treatments. The UVC treatments did not show any noticeable effect on the biofilms.

Underground Ecosystem Conservation Through High-resolution Air Monitoring.

In cave ecosystems tourists represent moving sources of discontinuous disturbances, able to induce transient system responses whose knowledge is crucial in defining appropriate conservation measures. Here we propose an approach to evaluate the amplitude and scales of cave alterations based on high-resolution air monitoring, through the use of purposely developed low-cost monitoring stations and a consistent analytical framework for information retrieval based on time series analysis. In particular, monitoring stations adopt a modular structure based on physical computing platforms acquiring data through several sensors, with means of preventing humidity damages and guaranteeing their continuous operation. Data are then analyzed using wavelet periodograms and cross-periodograms to extract the scales of tourism-induced alterations. The approach has been exemplified in the Pertosa-Auletta Cave, one of the most important underground environments in Southern Italy, highlighting the development of monitoring stations and the information obtainable with the proposed analytical workflow. Here, 2 monitoring stations acquiring data for 1 year at 1' sampling time on temperature, relative humidity, CO2, VOCs, and particulate matter were deployed in trails subjected to different levels of tourism. In terms of Pertosa-Auletta Cave air dynamics, the approach allowed estimating the temporal and spatial scales of tourism-induced alterations in the order of minutes and meters, respectively, with parameter-dependent variations. On more general terms, the approach proved reliable and effective, with its modularity and low-cost fostering its straightforward adoption in other underground ecosystems, where it can support the development of tailored management strategies.

Microbial Community Characterizing Vermiculations from Karst Caves and Its Role in Their Formation.

The microbiota associated with vermiculations from karst caves is largely unknown. Vermiculations are enigmatic deposits forming worm-like patterns on cave walls all over the world. They represent a precious focus for geomicrobiological studies aimed at exploring both the microbial life of these ecosystems and the vermiculation genesis. This study comprises the first approach on the microbial communities thriving in Pertosa-Auletta Cave (southern Italy) vermiculations by next-generation sequencing. The most abundant phylum in vermiculations was Proteobacteria, followed by Acidobacteria > Actinobacteria > Nitrospirae > Firmicutes > Planctomycetes > Chloroflexi > Gemmatimonadetes > Bacteroidetes > Latescibacteria. Numerous less-represented taxonomic groups (< 1%), as well as unclassified ones, were also detected. From an ecological point of view, all the groups co-participate in the biogeochemical cycles in these underground environments, mediating oxidation-reduction reactions, promoting host rock dissolution and secondary mineral precipitation, and enriching the matrix in organic matter. Confocal laser scanning microscopy and field emission scanning electron microscopy brought evidence of a strong interaction between the biotic community and the abiotic matrix, supporting the role of microbial communities in the formation process of vermiculations.

Germination Behavior and Geographical Information System-Based Phenotyping of Root Hairs to Evaluate the Effects of Different Sources of Black Soldier Fly (Hermetia illucens) Larval Frass on Herbaceous Crops.

Insect larval frass has been proposed as a fertilizer and amendment, but methods for testing its effects on plants are poorly developed and need standardization. We obtained different types of black soldier fly (Hermetia illucens) frass via the factorial combination of (a) two insect diets, as follows: G (Gainesville = 50% wheat bran, 30% alfalfa meal, 20% maize meal) and W (43% sheep whey + 57% seeds); (b) two frass thermal treatments: NT = untreated and T = treated at 70 °C for 1 h. We tested the effects on the germination of cress (Lepidium sativum L.) and wheat (Triticum durum Desf.) by applying 1:2 w:w water extracts at 0, 25, 50, 75 and 100% concentration. Standardizing frass water content before extraction affected chemical composition. Frass extracts showed high electrical conductivity (8.88 to 13.78 mS cm-1). The W diet was suppressive towards Escherichia coli and showed a lower content of nitrates (e.g., WNT 40% lower than GNT) and a concentration-dependent phytotoxic effect on germinating plants. At 25% concentration, germination indices of G were 4.5 to 40-fold those at 100%. Root and shoot length and root hair area were affected by diet and concentration of frass extracts (e.g., root and shoot length in cress at 25% were, respectively, 4.53 and 2 times higher than at 100%), whereas the effects of the thermal treatment were few or inconclusive. On barley (Hordeum vulgare L.) grown in micropots on a silty loam soil, root mass was reduced by 37% at high extract concentration. A quick procedure for root hair surface area was developed based on the geographic information system (GIS) and may provide a fast method for incorporating root hair phenotyping in frass evaluation. The results indicate that below-ground structures need to be addressed in research on frass effects. For this, phyotoxicity tests should encompass different extract dilutions, and frass water content should be standardized before extraction in the direction of canonical procedures to allow comparisons.

Leaf metabolomics and molecular networking of wild type and mutant genotypes of chia (Salvia hispanica L.).

Salvia hispanica L., commonly named Chia, is a food plant from Central America and Australia, producing seeds whose consumption has been increasing in the last decade. Several articles analysed the seeds metabolite content. However, few is known about Chia leaves. This work is the first report on the whole metabolite profile of chia leaves, determined by spectroscopic methods including NMR, GC-MS and LC-MS coupled with chemometrics analysis. Additionally, molecular networking has been applied to the LC-MS data to determine the flavonoid composition. Different chia sources were compared: one commercial (black) and three early flowering (G3, G8 and G17) mutant genotypes cultivated at two irrigation regimes (50 and 100%). Organic extracts were mainly composed by saturated and mono- and polyunsaturated fatty acids with palmitic being the most abundant followed by oleic and linolenic acids. Aqueous extracts contained glucose, galactose, and fructose as main sugars. Flavonoids were based on vitexin and orientin and their analogues. Chemical composition of early flowering genotypes was quite similar to commercial black chia with the exception of G8 showing significant differences in the polar phase. A generally highest content of omega-9 fatty acids has been found in the early flowering genotypes along with high content of nutraceuticals suggesting them as a potential source of raw materials for the food/feed industry.

Tourism affects microbial assemblages in show caves.

Anthropogenic disturbance on natural ecosystems is growing in frequency and magnitude affecting all ecosystems components. Understanding the response of different types of biocoenosis to human disturbance is urgently needed and it can be achieved by adopting a metacommunity framework. With the aid of advanced molecular techniques, we investigated sediment communities of Fungi, Bacteria and Archaea in four Italian show caves, aiming to disentangle the effects induced by tourism on their diversity and to highlight changes in the driving forces that shape their community composition. We modelled diversity measures against proxies of tourism pressure. With this approach we demonstrate that the cave tourism has a direct effect on the community of Bacteria and an indirect influence on Fungi and Archaea. By analysing the main driving forces influencing the community composition of the three microbial groups, we highlighted that stochastic factors override dispersal-related processes and environmental selection in show caves compared to undisturbed areas. Thanks to this approach, we provide new perspectives on the dynamics of microbial communities under human disturbance suggesting that a proper understanding of the underlying selective mechanisms requires a comprehensive and multi-taxonomic approach.

Geomicrobiology of a seawater-influenced active sulfuric acid cave.

Fetida Cave is an active sulfuric acid cave influenced by seawater, showing abundant microbial communities that organize themselves under three main different morphologies: water filaments, vermiculations and moonmilk deposits. These biofilms/deposits have different cave distribution, pH, macro- and microelement and mineralogical composition, carbon and nitrogen content. In particular, water filaments and vermiculations had circumneutral and slightly acidic pH, respectively, both had abundant organic carbon and high microbial diversity. They were rich in macro- and microelements, deriving from mineral dissolution, and, in the case of water filaments, from seawater composition. Vermiculations had different color, partly associated with their mineralogy, and unusual minerals probably due to trapping capacities. Moonmilk was composed of gypsum, poor in organic matter, had an extremely low pH (0-1) and low microbial diversity. Based on 16S rRNA gene analysis, the microbial composition of the biofilms/deposits included autotrophic taxa associated with sulfur and nitrogen cycles and biomineralization processes. In particular, water filaments communities were characterized by bacterial taxa involved in sulfur oxidation and reduction in aquatic, aphotic, microaerophilic/anoxic environments (Campylobacterales, Thiotrichales, Arenicellales, Desulfobacterales, Desulforomonadales) and in chemolithotrophy in marine habitats (Oceanospirillales, Chromatiales). Their biodiversity was linked to the morphology of the water filaments and their collection site. Microbial communities within vermiculations were partly related to their color and showed high abundance of unclassified Betaproteobacteria and sulfur-oxidizing Hydrogenophilales (including Sulfuriferula), and Acidiferrobacterales (including Sulfurifustis), sulfur-reducing Desulfurellales, and ammonia-oxidizing Planctomycetes and Nitrospirae. The microbial community associated with gypsum moonmilk showed the strong dominance (>60%) of the archaeal genus Thermoplasma and lower abundance of chemolithotrophic Acidithiobacillus, metal-oxidizing Metallibacterium, Sulfobacillus, and Acidibacillus. This study describes the geomicrobiology of water filaments, vermiculations and gypsum moonmilk from Fetida Cave, providing insights into the microbial taxa that characterize each morphology and contribute to biogeochemical cycles and speleogenesis of this peculiar seawater-influenced sulfuric acid cave.