Alterations in Arbuscular Mycorrhizal Community Along a Chronosequence of Teak (Tectona grandis) Plantations in Tropical Forests of China

Arbuscular mycorrhizal (AM) fungi play a crucial role in promoting plant growth, enhancing plant stress resistance, and sustaining a healthy ecosystem. However, little is known about the mycorrhizal status of teak plantations. Here, we evaluated how the AM fungal communities of rhizosphere soils and roots respond to different stand ages of teak: 22, 35, 45, and 55-year-old from the adjacent native grassland (CK). A high-throughput sequencing method was used to compare the differences in soil and root AM fungal community structures. In combination with soil parameters, mechanisms driving the AM fungal community were revealed by redundancy analysis and the Mantel test. Additionally, spore density and colonization rates were analyzed. With increasing stand age, the AM fungal colonization rates and spore density increased linearly. Catalase activity and ammonium nitrogen content also increased, and soil organic carbon, total phosphorous, acid phosphatase activity, available potassium, and available phosphorus first increased and then decreased. Stand age significantly changed the structure of the AM fungal community but had no significant impact on the diversity of the AM fungal community. However, the diversity of the AM fungal community in soils was statistically higher than that in the roots. In total, nine and seven AM fungal genera were detected in the soil and root samples, respectively. The majority of sequences in soils and roots belonged to Glomus. Age-induced changes in soil properties could largely explain the alterations in the structure of the AM fungal community along a chronosequence, which included total potassium, carbon-nitrogen ratio, ammonium nitrogen, catalase, and acid phosphatase levels in soils and catalase, acid phosphatase, pH, and total potassium levels in roots. Soil nutrient availability and enzyme activity were the main driving factors regulating the shift in the AM fungal community structure along a chronosequence of the teak plantations.

90. Impact of Infection Control Assessment and Response (ICAR) Visit on Candida auris Colonization Rates at Seven Long Term Acute Care Hospitals (LTACH) in Los Angeles County

Background Public health authorities often use Infection Control Assessment and Response (ICAR) visits during Candida auris (C. auris) outbreak investigation to identify facility-level infection prevention and control (IPC) practice gaps and make recommendations to address those gaps. As an adjunct to ICAR visit, point prevalence surveys (PPS) provide an objective measure to determine if IPC recommendations are implemented. Because they require significant public health resources to perform, we evaluated the impact of ICAR visits on C. auris colonization rates. Methods PPS were conducted at seven long-term acute-care hospitals (LTACH) with C. auris outbreaks in Los Angeles County from July 2020 to May 2021. Skin swabs collected at PPS were tested for C. auris colonization by PCR technique. Pre-ICAR PPS results were compared with the average of two serial post-ICAR PPS results using repeated measures ANOVA test. Linear regression was used to estimate associations between individual ICAR domains and C. auris colonization. Results 54 PPS were conducted at seven LTACHs with at least one ICAR visit made for every two PPS. On average, PPS were conducted 14 days (range 1-15 days) before and 10 days (range 4-33 days) after an ICAR visit. PPS positive rates with ICAR visit dates for each LTACH are shown in figure 1. Overall, ICAR visits were associated with a significant decrease (p=0.035) in the average of the positive rates in two serial post-ICAR PPS. When individual domain (hand hygiene, contact precautions, and environmental disinfection) of ICAR tool was analyzed, only adherence to environmental disinfection was significantly associated (p=0.038) with decrease in C. auris colonization rates. There was a moderate negative correlation (R2 = 0.26, β= -0.33) between environmental disinfection adherence and the magnitude of decrease in the colonization rates across all LTACHs (Figure 2). Figure 1 Figure 2 Conclusion ICAR visits were found to be significantly associated with a decrease in the average PPS positive rate on serial PPS. Parts of the ICAR tool that assessed environmental disinfection at the facility seemed most correlated with decrease in C. auris colonization rate. Streamlining the ICAR process to focus on the most impactful parts of ICAR tool may be a more efficient intervention to control C. auris outbreaks. Disclosures All Authors: No reported disclosures

Beneficial Effects of the Five Isolates of Funneliformis mosseae on the Tomato Plants Were Not Related to Their Evolutionary Distances of SSU rDNA or PT1 Sequences in the Nutrition Solution Production

The symbiosis and beneficial effects of arbuscular mycorrhizal fungi (AM fungi) on plants have been widely reported; however, the effects might be unascertained in tomato industry production with coconut coir due to the nutrition solution supply, or alternatively with isolate-specific. Five isolates of AM fungi were collected from soils of differing geographical origins, identified as Funneliformis mosseae and evidenced closing evolutionary distances with the covering of the small subunit (SSU) rDNA regions and Pi transporter gene (PT1) sequences. The effects of these isolates on the colonization rates, plant growth, yield, and nutrition uptake were analyzed in tomato nutrition solution production with growing seasons of spring–summer and autumn–winter. Our result indicated that with isolate-specific effects, irrespective of geographical or the SSU rDNA and PT1 sequences evolution distance, two isolates (A2 and NYN1) had the most yield benefits for plants of both growing seasons, one (E2) had weaker effects and the remaining two (A2 and T6) had varied seasonal-specific effects. Inoculation with effective isolates induced significant increases of 29.0–38.0% (isolate X5, T6) and 34.6–36.5% (isolate NYN1, T6) in the plant tissues respective nitrogen and phosphorus content; the plant biomass increased by 18.4–25.4% (isolate T6, NYN1), and yields increased by 8.8–12.0% (isolate NYN1, A2) compared with uninoculated plants. The maximum root biomass increased by 28.3% (isolate T6) and 55.1% (isolate E2) in the autumn–winter and spring–summer growing seasons, respectively. This strong effect on root biomass was even more significant in an industry culture with a small volume of substrate per plant. Our results reveal the potential benefits of using selected effective isolates as a renewable resource that can overcome the suppressing effects of sufficient nutrient availability on colonization rates, while increasing the yields of industrially produced tomatoes in nutrition solution with coconut coir.

To Study and Compare the Effect of Pre-Operative Skin Preparation with Aqueous Povidone Iodine Only and in Combination with Alcoholic Chlorhexidine on Surgical Site Infection in Tertiary Care Hospital SVRRGGH, Tirupati

BACKGROUND Even the normal skin of healthy humans usually harbours a rich bacterial flora, which are usually non-pathogenic. But these organisms always have a potential to cause infection of the surgical site. The aim of surgical site preparation with antiseptics is to remove microorganisms harbouring the skin surface to a lower level. Povidine iodine (iodophors) and chlorhexidine are the agents most often used for pre-operative surgical site antisepsis. In this study, we wanted to determine the efficacy of pre-operative skin preparation with aqueous povidone iodine alone and when used in combination with alcoholic chlorhexidine for surgical site asepsis. METHODS This is a cross-sectional study. 200 patients (100 in each group) were considered for the study who were undergoing clean elective surgery. Pre-operative preparation of skin in the surgical area was done by the respective antiseptic which was planned accordingly, after such application, sterile saline swab culture was taken immediately from the site of incision during surgery. In the cases which showed growth of organisms, they were isolated from colonies and subjected to gram staining, coagulase test and antibiotic sensitivity test. The organisms thus isolated were identified by their morphological and cultural characteristics and difference in colonization rates were considered as a measure of antiseptic regimen efficacy. RESULTS The results showed that, usage of povidine iodine along with alcoholic chlorhexidine is more efficacious and showed significant reduction of colonization rates at the site of incision, in comparison to using povidone iodine alone. Postoperative wound infections were lower, when povidine iodine is used in combination with chlorhexidine is used for pre-operative surgical site preparation. CONCLUSIONS Pre-operative skin preparation with the chlorhexidine gluconate 2.5 % v/v in 70 % propanol followed by aqueous povidone-iodine solution is an ideal for broad spectrum asepsis and the post-operative wound infection rate is much lower as compared to povidone iodine alone. KEYWORDS Skin Disinfection; Chlorhexidine; Propanol; Povidone-iodine; Bacterial Colonization

Nesting of arboreal ants (Hymenoptera: Formicidae) in artificial substrates in coffee plantations in the Colombian Andes

Ants can provide pest biocontrol for coffee crops; however, this ecosystem service may decline in intensively managed plantations due to the loss of nesting resources. Considering how to increase the number of ants, we studied if they nest in different types of artificial substrates attached to coffee bushes both in shade-grown and sun-grown coffee plantations. Three independent tests were conducted at some coffee plantations in southwestern Colombia with the purpose of answering the following questions: 1) Do ants nest in artificial substrates made from recyclable materials? 2) Do the types of substrate (materials and configuration) and coffee management (shade-grown vs. sun-grown coffee) affect colonization rates, richness, and identity of colonizing ants? 3) Does time affect substrate colonization rates? Each experiment independently compared different substrate materials and designs, in both shade and sun-grown coffee. Results showed preference of one of the substrates offered and higher nesting rates in shade-grown plantations. Eight ant species were found nesting in artificial substrates, most of them being arboreal generalists. A higher number of ant species colonized substrates in shade-grown plantations; however, the effect was not statistically significant. Nesomyrmex asper and Crematogaster spp. were always found nesting in both types of plantation. There was a trend to increase nesting activity with time in shade-grown coffee but not in sun-grown coffee. Evidence supports that offering artificial substrates enhances arboreal ant nesting in coffee plantations.

Arbuscular Mycorrhizal Fungi Symbiosis in Durum Wheat (Triticum durum Desf.) under No-tillage and Tillage Practices in a Semiarid Region

Background: Arbuscular mycorrhizal fungi (AMF) are root symbionts that improve host plant growth and resilience against biotic and abiotic stresses allowing a sustain plant production particularly under harsh conditions. Methods: The objective of this study is to compare the effect of conventional tillage and no-tillage practices on AMF symbiosis with durum wheat (Triticum durum Desf) through the evaluation of root colonization and AMF spore density in the soil of three different sites in a semi-arid region in Algeria. Two sites were conducted under rain-fed conditions and one was irrigated.Result: Mycorrhizal root colonization varied according to the site and the tillage practice, while spore density differed between sites. Spore density was higher in sites under rain-fed conditions suggesting that water deficit stimulate sporulation, while root colonization seems to be limited by drought. No-tillage improved root colonization rates by 54.3% compared to conventional tillage system and this improvement, particularly the arbuscular percentage, was higher under drought conditions. In addition, root colonization rates showed a positive correlation with the organic matter content and pH in the soil and a negative correlation with the available phosphorus in the soil. These results indicate that no-tillage enhance the establishment of AMF symbiosis with durum wheat under semi-arid conditions.

Micro-Landscape Dependent Changes in Arbuscular Mycorrhizal Fungal Community Structure

The roots of most plants host diverse assemblages of arbuscular mycorrhizal fungi (AMF), which benefit the plant hosts in diverse ways. Even though we understand that such AMF assemblages are non-random, we do not fully appreciate whether and how environmental settings can make them more or less predictable in time and space. Here we present results from three controlled experiments, where we manipulated two environmental parameters, habitat connectance and habitat quality, to address the degree to which plant roots in archipelagos of high connectivity and invariable habitats are colonized with (i) less diverse and (ii) easier to predict AMF assemblages. We observed no differences in diversity across our manipulations. We show, however, that mixing habitats and varying connectivity render AMF assemblages less predictable, which we could only detect within and not between our experimental units. We also demonstrate that none of our manipulations favoured any specific AMF taxa. We present here evidence that the community structure of AMF is less responsive to spatio-temporal manipulations than root colonization rates which is a facet of the symbiosis which we currently poorly understand.

Pelopidas mathias (rice skipper).

Due to its wide host range and low reproductive potential, colonization rates of P. mathias are rather low compared to more specialized rice pests. Those ovipositing adults that do arrive do so after significant numbers of natural enemies have built up; this helps to explain the normally low pest status of P. mathias.

The influence of antibiotics on transitory resistome during gut colonization with CTX-M-15 and OXA-162 producing Klebsiella pneumoniae ST15

Great efforts have been made to limit the transmission of carbapenemase-producing Enterobacteriaceae (CPE), however, the intestinal reservoir of these strains and its modulation by various antibiotics remain largely unexplored. Our aim was to assess the effects of antibiotic administration (ampicillin, ceftazidime, ciprofloxacin) on the establishment and elimination of intestinal colonization with a CTX-M-15 ESBL and OXA-162 carbapenemase producing Klebsiella pneumoniae ST15 (KP5825) in a murine (C57BL/6 male mice) model. Whole genome sequencing of KP5825 strain was performed on an Illumina MiSeq platform. Conjugation assays were carried out by broth mating method. In colonization experiments, 5 × 106 CFU of KP5825 was administered to the animals by orogastric gavage, and antibiotics were administered in their drinking water for two weeks and were changed every day. The gut colonization rates with KP5825 were assessed by cultivation and qPCR. In each of the stool samples, the gene copy number of blaOXA-162 and blaCTX-M-15 were determined by qPCR. Antibiotic concentrations in the stool were determined by high pressure liquid chromatography and a bioanalytical method. The KP5825 contained four different plasmid replicon types, namely IncFII(K), IncL, IncFIB and ColpVC. IncL (containing the blaOXA-162 resistance gene within a Tn1991.2 genetic element) and IncFII(K) (containing the blaCTX-M-15 resistance gene) plasmids were successfully conjugated. During ampicillin and ceftazidime treatments, colonization rate of KP5825 increased, while, ciprofloxacin treatments in both concentrations (0.1 g/L and 0.5 g/L) led to significantly decreased colonization rates. The gene copy number blaOXA-162 correlated with K. pneumoniae in vivo, while a major elevation was observed in the copy number of blaCTX-M-15 from the first day to the fifteenth day in the 0.5 g/L dose ceftazidime treatment group. Our results demonstrate that commonly used antibiotics may have diverse impacts on the colonization rates of intestinally-carried CPE, in addition to affecting the gene copy number of their resistance genes, thus facilitating their stable persistance and dissemination.