Insights into the functional role of Actinomycetia in promoting plant growth and biocontrol in tea (Camellia sinensis) plants.

Tea, a highly aromatic and globally consumed beverage, is derived from the aqueous infusion of dried leaves of Camellia sinensis (L.) O. Kuntze. Northeast India, encompassing an expansive geographical area between 24° and 27° N latitude and 88° and 95° E longitude, is a significant tea-producing region covering approximately 312,210 hectares. Despite its prominence, this region faces persistent challenges owing to a conducive climate that harbors the prevalence of pests, fungal pathogens, and weeds, necessitating agrochemicals. Helopeltis theivora, Oligonychus coffeae, and Biston suppressaria are prominent among the tea pests in this region. Concurrently, tea plants encounter fungal infections such as blister blight, brown root rot, and Fusarium dieback. The growing demand for safer tea production and the need to reduce pesticide and fertilizer usage has spurred interest in exploring biological control methods. This review focuses on Actinomycetia, which potentially safeguards plants from diseases and pest infestations by producing many bioactive substances. Actinomycetia, which resides in the tea rhizosphere and internal plant tissues, can produce antagonistic secondary metabolites and extracellular enzymes while promoting plant growth. Harnessing the biocontrol potential of Actinomycetia offers a promising solution to enhance tea production, while minimizing reliance on harmful agrochemicals, contributing to a more environmentally conscious and economically viable tea cultivation system.

Evaluating the Potential of Bacillus Isolates for Chlorpyrifos Degradation and Their Role in Tea Growth Promotion and Suppression of Pathogens.

Pesticides employed for controlling domestic and agricultural pests are among the most dangerous environmental contaminants. Nevertheless, negligent usage and a lack of technical expertise have led to the contamination and pollution of various ecological niches. The extensive utilization of the organophosphate chlorpyrifos (CPs) for insect infestation control, coupled with its detrimental effects and persistence in the ecosystem, has led to calls for its removal from contaminated sites. The study is mainly focused on degradation of CPs; using viz. Bacillus wiedmannii A3 and Bacillus cereus P14 isolated from tea rhizosphere soil having pesticide contamination in Sonitpur district, Assam, India. These two bacterial strains were able to degrade CPs in vitro within 3 days. Reverse-phase HPLC analysis suggested about 96% reduction of CPs concentration upon bacterial treatment. Again, in case of A3, GC-MS analysis revealed that CPs was modified to 2-hydroxy-3,5,6-trichloropyridine and chlorpyrifos-oxon, thus finally metabolized into non-toxic products. While analyzing P14, silane, dimethyl (2,2,2-trichloroethoxy) propoxy, and 3-aminobenzoic acid, N-trimethylsilyl-, trimethylsilyl ester were identified. These compounds were subsequently transformed into non-toxic products. In addition to this, they demonstrated a significant boost of plant growth-promoting traits in both absence and presence of CPs; also showed growth development in nursery scale condition. Moreover, they functioned as biocontrol agents against Phellinus lamaensis and Colletotrichum gloeosporioides, responsible for brown root rot and anthracnose in North East India tea plantations, respectively. Thus, the pesticide-tolerant Bacilli strains A3 and P14 could be used as bioremediation of contaminated sites and also as biostimulants, and biocontrols in tea crop production.

Antimicrobial potentiality of actinobacteria isolated from two microbiologically unexplored forest ecosystems of Northeast India.

BACKGROUND: Actinobacteria are often known to be great producers of antibiotics. The rapid increase in the global burden of antibiotic-resistance with the concurrent decline in the discovery of new antimicrobial molecules necessitates the search for novel and effective antimicrobial metabolites from unexplored ecological niches. The present study investigated the antimicrobial producing actinobacterial strains isolated from the soils of two microbiologically unexplored forest ecosystems, viz. Nameri National Park (NNP) and Panidehing Wildlife Sanctuary (PWS), located in the Eastern Himalayan Biodiversity hotspot region. RESULTS: A total of 172 putative isolates of actinobacteria were isolated, of which 24 isolates showed strong antimicrobial bioactivity. Evaluation of the ethyl acetate extracts of culture supernatants against test microbial strains revealed that isolates PWS22, PWS41, PWS12, PWS52, PWS11, NNPR15, NNPR38, and NNPR69 were the potent producers of antimicrobial metabolites. The antimicrobial isolates dominantly belonged to Streptomyces, followed by Nocardia and Streptosporangium. Some of these isolates could be putative novel taxa. Analysis of the antimicrobial biosynthetic genes (type II polyketide synthase and nonribosomal peptide synthetase genes) showed that the antimicrobial metabolites were associated with pigment production and belonged to known families of bioactive secondary metabolites. Characterization of the antimicrobial metabolites of Streptomyces sp. PWS52, which showed lowest taxonomic identity among the studied potent antimicrobial metabolite producers, and their interaction with the test strains using GC-MS, UHPLC-MS, and scanning electron microscopy revealed that the potential bioactivity of PWS52 was due to the production of active antifungal and antibacterial metabolites like 2,5-bis(1,1-dimethylethyl) phenol, benzeneacetic acid and nalidixic acid. CONCLUSIONS: Our findings suggest that the unexplored soil habitats of NNP and PWS forest ecosystems of Northeast India harbor previously undescribed actinobacteria with the capability to produce diverse antimicrobial metabolites that may be explored to overcome the rapidly rising global concern about antibiotic-resistance.