Browsing by Author "Aloo, Becky"

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Advancement and practical applications of rhizobacterial biofertilizers for sustainable crop production in sub-Saharan Africa
(BioMed Central, 2021-12-13) Aloo, Becky; Mbega, Ernest; Tumuhairwe, John; Makumba, Billy
Agricultural intensification continues in Africa in attempts to meet the rising food demands of the equally rising population. However, most arable lands in the region are characterized by nutrient deficiency and over-reliance on synthetic fertilizers which consequently contributes to increased production costs, environmental pollution, and global warming. Decades of research on plant–rhizobacterial interactions have led to the formulation and commer- cialization of rhizobacterial biofertilizers globally for sustainable soil and crop health. Nevertheless, this promising technology has not received much attention in Africa and remains largely unexplored due to several constraints. This article discusses the practical applications of rhizobacterial biofertilizers for sustainable crop production in sub-Saha- ran Africa. The challenges of soil infertility and the use of conventional synthetic fertilizers in crop production in Africa are critically evaluated. An overview of the potential of rhizobacteria as biofertilizers and alternatives to synthetic fertilizers for soil fertility and crop productivity in the continent is also provided. The advantages that these biofertiliz- ers present over their synthetic counterparts and the status of their commercialization in the African region are also assessed. Finally, the constraints facing their formulation, commercialization, and utilization and the prospects of this promising technology in the region are deliberated upon. Such knowledge is valuable towards the full exploitation and adoption of this technology for sustainable agriculture for Africa’s food security.
Characterization of rhizobacteria and their formulation into biofertilizers for potato (solanum tuberosum l.) growth promotion in Tanzania
(NM-AIST, 2021-07) Aloo, Becky
Rhizobacteria and their plant growth-promoting (PGP activities have widely been investigated as biofertilizers for many crops but rarely for the potato (Solanum tuberosum L.). In the present study, potato-grown soils from three agro-ecological zones in Tanzania were sampled, characterized, and a total of 145 rhizobacteria isolated from them. The isolates were screened in vitro for PGP activities like nutrients solubilization, nitrogen fixation, and phytohormones production, and 52 most-promising isolates were characterized and identified by 16S-rRNA sequencing. Their effects on pot-grown potatoes were evaluated against non-inoculated plants as controls. Klebsiella grimontii MPUS7, Serratia marcescens NGAS9, and Citrobacter freundii LUTT5 were selected based on their effects on pot-grown potatoes and formulated in different carrier materials as possible biofertilizers. Their shelf lives were determined as colony-forming units (CFU) under refrigerated (8 o C) and room conditions (25 ± 2 o C) for eight months and their effects on field-grown potatoes evaluated against recommended fertilizers and non-treated plants. Data analysis involved XLSTAT (2.3). Significant differences (p ≤ 0.05) were evident for the fertility-related properties of the sampled soils but not their nutrient contents. Though slightly acidic (pH < 6.5), non-saline (Electrical conductivity < 1 dS m -1 ), and greater proportions of silt + clay (average 46.85 ± 15.18%) than gravel and sand, the soils contained low nutrient levels which may not be ideal for potato production. The rhizobacteria significantly differed in their invitro PGP activities. Except for the number of days to emergence and flowering, rhizosphere soil pH, and salinity, potato growth-related parameters like tuber numbers, sizes, weights, and nutrient contents were enhanced by the rhizobacterial treatments in the screen house by up to 90%. The PM-1 formulation supported the maximum K. grimontii MPUS7 growth (5.3 log-CFU g -1 ) under refrigeration and C. freundii LUTT5 (4.1 log-CFU g -1 ) under refrigerated and room conditions but the highest K. grimontii MPUS7 population (3.7 log-CFU g -1 ) was realized in room-stored PM-4. The formulations also showed varied activities at enhancing potato growth and most had similar or greater effects on potato growth as the artificial fertilizers and can effectively be used to replace the use of synthetic fertilizers in potato production systems in Tanzania.
Effects of agrochemicals on the beneficial plant rhizobacteria in agricultural systems
(Springer Nature, 2021-09-18) Aloo, Becky; Mbega, Ernest; Makumba, Billy; Tumuhairwe, John
Conventional agriculture relies heavily on chemical pesticides and fertilizers to control plant pests and diseases and improve production. Nevertheless, the intensive and prolonged use of agrochemicals may have undesirable consequences on the structure, diversity, and activities of soil microbiomes, including the beneficial plant rhizobacteria in agricultural systems. Although literature continues to mount regarding the effects of these chemicals on the beneficial plant rhizobacteria in agricultural systems, our understanding of them is still limited, and a proper account is required. With the renewed efforts and focus on agricultural and environmental sustainability, understanding the effects of different agrochemicals on the beneficial plant rhizobacteria in agricultural systems is both urgent and important to deduce practical solutions towards agricultural sustainability. This review critically evaluates the effects of various agrochemicals on the structure, diversity, and functions of the beneficial plant rhizobacteria in agricultural systems and propounds on the prospects and general solutions that can be considered to realize sustainable agricultural systems. This can be useful in understanding the anthropogenic effects of common and constantly applied agrochemicals on symbiotic systems in agricultural soils and shed light on the need for more environmentally friendly and sustainable agricultural practices.
Effects of Carrier Materials and Storage Temperatures on the Viability and Stability of Three Biofertilizer Inoculants Obtained from Potato (Solanum tuberosum L.) Rhizosphere
(MDPI, 2022-01-20) Aloo, Becky; Mbega, Ernest; Makumba, Billy; Tumuhairwe, John
Biofertilizer technology continues to be derailed by the short shelf life of inoculants. The present study investigated the suitability of wheat-bran (WB), rice-husks (RH), farmyard-manure (FYM), bagasse (BG), and sawdust (SD) in the formulation of potato-derived Klebsiella grimontii (MPUS7), Serratia marcescens (NGAS9), and Citrobacter freundii (LUTT5) under refrigerated (8 °C) and room (25 ± 2 °C) storage. The physicochemical properties of the materials were assessed before sterilization and introduction of the inoculants and assessment of their viability for 8 months. Most of the physicochemical properties of the materials varied significantly (p < 0.05). Bagasse supported the maximum growth of MPUS7 (5.331 log CFU g−1) under refrigeration and LUTT5 (4.094 log CFU g−1) under both conditions. Under room storage, the maximum growth of MPUS7 (3.721 log CFU g−1) occurred in WB. Formulations that remained viable under room storage can easily be integrated into existing agricultural distribution systems that lack refrigeration.
Endophytic Rhizobacteria for Mineral Nutrients Acquisition in Plants: Possible Functions and Ecological Advantages
(Springer Nature Switzerland AG., 2021-03-05) Aloo, Becky; Tripathi, Vishal; Mbega, Ernest; Makumba, Billy A.
Nutrient-deficiency in agricultural soils is a major problem in many parts of the world, it is, therefore, artificial fertilizers are widely used to boost crop production. Unfortunately, these fertilizers are associated with a myriad of environmental problems hence, there is a need for viable alternatives. The realization that the plant microbiome can improve plant health, soil fertility, and crop productivity is one of the most fascinating scientific discoveries in the world. For several decades, rhizobacteria have been studied due to their various plant growth-promoting (PGP) traits. Endophytic rhizobacteria are unique plant microbiome that establish themselves within plant root tissues and exert beneficial functions to their hosts without harming them. A lot of emphases have been put on these bacteria as viable tools for sustainable agriculture and it is advanced that they could be better plant growth promoters than their external counterparts. However, this theory is not yet clearly understood. This chapter provides the current state of understanding of the putative functions of endophytic rhizobacteria and their future prospects for plant mineral nutrients acquisition. Their advantageous traits that largely advanced to facilitate these PGP functions are also discussed. Such informations can provide better opportunities for improved plant mineral nutrients acquisition and enhance the application of these microbes as viable strategies for sustainable agriculture.
Life Inside Plants: Insights into the Lifestyle, Diversity, and Metabolites of Endophytic Bacteria Involved in Plant Defense Against Phytopathogens
(Springer Nature, 2022-05-05) Aloo, Becky; Mbega, Ernest; Makumba, Billy; Tumuhairwe, John
One of the pressing issues in agriculture today is low crop yields due to plant diseases and pathogens. Chemical pesticides have generously been applied as remedies to improve the situation, but continue to be shunned globally due to their long-term environmental impacts. Endophytes are microbes that live symbiotically in plant tissues and are continually being associated with the suppression of phytopathogens and plant health. Thus, they present an environmentally-friendly option in plant defense against phytopathogens. However, their diversity, lifestyle, and roles in plant defense against phytopathogens are still not well-understood. This chapter explores the lifestyle of endophytic bacteria and discusses their diversity and metabolites involved in plant defense against phosphagens. The chapter further examines the future prospects and evaluates the emerging gaps relative to their use in plant defense against phytopathogens. Such knowledge is critical in fully exploiting their potential in sustainable agriculture.
Molecular Identification and In Vitro Plant Growth-Promoting Activities of Culturable Potato (Solanum tuberosum L.) Rhizobacteria in Tanzania
(Springer Nature Switzerland AG., 2020-08-21) Aloo, Becky; Mbega, Ernest; Makumba, Billy; Hertel, Robert; Daniel, Rolf
The present study investigated the diversity of culturable rhizobacteria associated with potato (S. tuberosum L.) in Tanzania and assessed their in vitro plant growth-promoting (PGP) activities to deduce their potential as biofertilizers. Potato rhizosphere soil and tuber samples (54 samples in total) were collected from 9 villages in three different agro-ecological regions in Tanzania. A total of 145 rhizobacterial isolates were obtained, 52 of which were selected and identified by partial 16S rRNA gene sequences and screened for various PGP traits in vitro including qualitative and quantitative solubilization of phosphorus (P), zinc (Zn) and potassium (K), nitrogen (N2) fixation and production of ammonia (NH3) in nitrogen-free medium, and indole-3-acetic acid (IAA), gibberellic acids (GA) and siderophores production. The results showed that the isolates were all Gammaproteobacteria, belonging to 4 families (Enterobacteriaceae, Yersiniaceae, Pseudomonadaceae and Morganellaceae) and 9 genera (Enterobacter, Klebsiella, Serratia, Pseudomonas, Morganella, Buttiauxella, Pantoea and Cedecea). Significant differences (P < 0.05) were observed for all assessed PGP abilities of the external and endophytic rhizobacterial isolates except for quantitative siderophore production and qualitative P and K solubilization for the external rhizobacteria and production of IAA and GA for the endophytic rhizobacteria. Among the best PGP isolates which can be exploited for biofertilization of the potato were Klebsiella pneumoniae KIBS1, K. grimontii LUTS10, Serratia liquefaciens KIBT1, Enterobacter ludwigii KIBS10 and Citrobacter freundii MWALS6. Comparative evaluation of PGP abilities of these two groups of isolates revealed significant differences (P < 0.05) only for NH3 and IAA production and qualitative K solubilization.
Nutrient Budgets for Sustained Crop Production in African Soils: Evidence from Potato-Grown Soils in Tanzania
(Springer Nature Singapore, 2024-11-12) Aloo, Becky; Tripathi, Vishal; Makumba, Billy; Mbega, Ernest
Soil fertility is under pressure worldwide due to agricultural intensification to match food demand. In sub-Saharan Africa (SSA), the depletion of soil nutrients is the root cause of the widespread food insecurity. Therefore, there is a need to continually monitor soil nutrient levels to drive policies and management options for sustained food production. Compared to other crops, potato (Solanum tuberosum L.) is increasingly becoming significant for food and economic security in SSA. The crop is, however, a heavy nutrient feeder and withdraws hefty amounts of nutrients from the soil which can interfere with its sustained production. However, very few studies have assessed the soil fertility levels of potato-grown soils in different parts of SSA. This chapter includes a case study report from the investigation of the fertility status and associated physicochemical properties of potato-grown soils in various agro-ecological areas in Tanzania. Soil samples collected from 27 potato farmlands were sampled in nine districts and analyzed for pH, electrical conductivity at 25 °C (EC25), soluble salts (SS), particle size distribution, potassium, phosphorus, iron, nitrogen, zinc, organic matter (OM), and organic carbon (OC) using standard methods. The results revealed significant differences for fertility-related physicochemical properties like EC25 (P = 0.004), (%) SS (P = 0.004), (%) OC (P = 0.018), and (%) OM (P = 0.019) in the soils but there were no significant differences for the fertility status of soils across the different study areas. Significant (P < 0.05) correlations were also observed for different parameters. The study concluded that specific soil characteristics differed significantly while fertility was relatively consistent. These findings serve as a basis for comprehending the existing soil conditions and can inform future strategies for sustainable soil management to ensure optimal nutrient levels to support the continued productivity of potatoes in the region.
Plant Growth Promoting Rhizobacterial Biofertilizers for Sustainable Crop Production: The Past, Present, and Future
(Preprints, 2020-09-26) Aloo, Becky; Makumb, Billy; Mbega, Ernest
The world’s population is increasing and so are agricultural activities to match the growing demand for food. Conventional agricultural practices generally employ artificial fertilizers to increase crop yields, but these have multiple environmental and human health effects. For decades, environmentalists and sustainability researchers have focused on alternative crop fertilization mechanisms to address these challenges, and biofertilizers have constantly been researched, recommended, and even successfully-adopted for several crops. Biofertilizers are microbial formulations made of indigenous plant growth-promoting rhizobacteria (PGPR) which can naturally improve plant growth either directly or indirectly, through the production of phytohormones, solubilization of soil nutrients, and production of iron-binding metabolites; siderophores. Biofertilizers, therefore, hold immense potential as tools for sustainable crop production especially in the wake of climate change and global warming. Despite the mounting interest in this technology, their full potential has not yet been realized. This review updates our understanding of the PGPR biofertilizers and sustainable crop production. It evaluates the history of these microbial products, assesses their present state of utilization, and also critically propounds on their future prospects for sustainable crop production. Such information is desirable to fully evaluate their potential and can ultimately pave the way for their increased adoption for crop production.
Plant growth-promoting rhizobacterial biofertilizers for crop production: The past, present, and future
(Frontiers, 2022-09-16) Aloo, Becky; Tripathi, Vishal; Makumba, Billy; Mbega, Ernest
Recent decades have witnessed increased agricultural production to match the global demand for food fueled by population increase. Conventional agricultural practices are heavily reliant on artificial fertilizers that have numerous human and environmental health effects. Cognizant of this, sustainability researchers and environmentalists have increased their focus on other crop fertilization mechanisms. Biofertilizers are microbial formulations constituted of indigenous plant growth-promoting rhizobacteria (PGPR) that directly or indirectly promote plant growth through the solubilization of soil nutrients, and the production of plant growth-stimulating hormones and iron- sequestering metabolites called siderophores. Biofertilizers have continually been studied, recommended, and even successfully adopted for the production of many crops in the world. These microbial products hold massive potential as sustainable crop production tools, especially in the wake of climate change that is partly fueled by artificial fertilizers. Despite the growing interest in the technology, its full potential has not yet been achieved and utilization still seems to be in infancy. There is a need to shed light on the past, current, and future prospects of biofertilizers to increase their understanding and utility. This review evaluates the history of PGPR biofertilizers, assesses their present utilization, and critically advocates their future in sustainable crop production. It, therefore, updates our understanding of the evolution of PGPR biofertilizers in crop production. Such information can facilitate the evaluation of their potential and ultimately pave the way for increased exploitation.
The potential of Bacilli rhizobacteria for sustainable crop production and environmental sustainability.
(Elsevier, 2019-02-01) Aloo, Becky; Makumba, Billy; Mbega, Ernest
Conventional agricultural practices often rely on synthetic fertilizers and pesticides which have immense and adverse effects on humans, animals and environments. To minimize these effects, scientists world over are now deeply engaged in finding alternative approached for crop production which are less dependent on chemical inputs. One such approach is the use of rhizospheric bacteria as vital components of soil fertility and plant growth promotion (PGP) through their direct and indirect processes in plant rhizospheres. Among the most studied rhizobacteria are the Bacilli, particularly for production of antibiotics, enzymes and siderophores all of which are important aspects of PGP. Despite this, little information is available especially on their potentiality in crop production and their direct application only involves a few species, leaving a majority of these important rhizobacteria unexploited. This paper gives an overview of the unique properties of Bacilli rhizobacteria as well as their different PGP mechanisms that if mined can lead to their successful application and agricultural sustainability. It further points out the missing aspects with regards to these important rhizobacteria that should be considered for future research. This information will be useful in analyzing the PGP abilities of Bacilli rhizobacteria with an aim of fully mining their potential for crop production and environmental sustainability.
Rhizobacteria-Based Technology for Sustainable Cropping of Potato (Solanum tuberosum L.)
(Springer, 2019-08-15) Aloo, Becky; Mbega, Ernest; Makumba, Amendi
Potato (Solanum tuberosum L.) is one of the most important food crops worldwide but its cultivation is affected by numerous challenges including pests, diseases and high fertiliser requirements which have associated environmental problems. The exploitation of plant rhizospheres and their associated rhizobacterial interactions has gathered momentum worldwide in search of environmentally-friendly approaches to crop culti- vation. A lot of literature exists on rhizobacterial associations and their biofertilisation or bioprotection roles in many plants. However, very scanty information is available on rhizobacterial functions and communities of the potato, an indication that they are still understudied. In this regard, more research is needed to understand and exploit them for the successful application of rhizobacteria-based technology in potato cropping. This review updates our knowledge of the beneficial rhizobacteria of the potato and documents their roles in its bioprotection, phytostimulation and biofertilisation while highlighting their potential in enhancing its production and productivity. The future prospects regarding the research on these important potato microflora are further discussed as a guide and a baseline for future research on them. This review shows that rhizobacteria-based technology is a viable option for potato biofertilisation and bioprotection and could be the missing link in its sustainable cropping. The adoption and full exploitation of this technology can be fast-tracked if we increase our under- standing of the subject matter.
Rhizosphere Bacteria and Rhizobacterial Formulations: Small Weapons in the Big Battle of Plant Disease Management
(Springer Nature, 2022-05-05) Aloo, Becky; Mbega, Ernest; Makumba, Billy; Tumuhairwe, John
Global food security continues to be threatened by plant pests and diseases. While chemical pesticides are conventionally used to combat these pests and diseases, their overreliance is worrying in the context of environmental sustainability, and alternative pest control mechanisms are necessary. Rhizobacteria are largely recognized for their beneficial functions in plant rhizospheres that culminate into bio-protection, and their exploration and exploitation are rapidly escalating. However, their full potential is yet to be realized. This chapter revisits the mechanisms of rhizobacteria as critical weapons in the continued battle of plant disease management and identifies the advances concerning their formulation and commercialization on a global scale. The chapter further identifies the challenges and opportunities regarding the application of rhizobacteria in plant disease management. Such information can increase our knowledge of rhizobacteria and plant disease management and enhance their exploitation for agricultural sustainability.
Status of biofertilizer research, commercialization, and practical applications: A global perspective
(Elsevier Inc., 2021) Aloo, Becky; Makumba, Billy; Mbega, Ernest
Most contemporary agricultural practices involve the use of synthetic fertilizers which have been linked to numerous deleterious consequences such as eutrophication of water bodies and emission of greenhouse gases. Biofertilizers offer viable and environmentally friendly alternatives. The positive effects of plant growth-promoting rhizobacteria have extensively been demonstrated several agronomically important crops under both controlled and field conditions. Despite the large volume of literature documenting the potential of these microbial inoculants as biofertilizers, their practical application has largely been hampered by several factors. This chapter presents the current knowledge of biofertilizer research, commercialization, and practical applications from the global perspective. The constraints facing their research and global application are also articulated. Finally, some prospects regarding their future research, commercialization and practical application for sustainable cropping systems are critically elucidated. It is anticipated that this will enable the full evaluation of the potential prospects of biofertilizers for sustainable agriculture and ecosystems globally.
Sustainable Food Production Systems for Climate Change Mitigation: Indigenous Rhizobacteria for Potato Bio-fertilization in Tanzania
(Springer Nature, 2021-03-26) Aloo, Becky; Mbega, Ernest; Makumba, Billy Amendi
The global rise in human population has led to the intensification of agricultural activities to meet the ever-rising food demand. The potato (Solanum tuberosum L.) is a crop with the potential to tackle food security issues in developing countries due to its short growth cycle and high nutrient value. However, its cultivation is heavily dependent on artificial fertilizers for yield maximization, which culminates in global warming and other environmental problems. There is need, therefore, for its alternative fertilization technologies to mitigate climate change. This study evaluated the potential of indigenous rhizobacteria for potato cropping in Tanzania. Ten potato rhizobacterial isolates belonging to Enterobacter, Klebsiella, Citrobacter, Serratia, and Enterobacter genera were obtained from a previous collection from different agro-ecological areas in Tanzania. The isolates were characterized culturally, microscopically, biochemically, and by their carbohydrate utilization patterns. Their in vitro plant growth-promoting (PGP) traits such as nitrogen fixation, solubilization of phosphates, potassium, and zinc, and production of siderophores, indole acetic acid, and gibberellic acids were then evaluated. Lastly, sterilized potato seed tubers were bacterized with the inoculants and grown in pots of sterile soil in a screen-house using untreated plants as a control experiment. The potato rhizobacterial isolates had varying characteristics and showed varying in vitro PGP activities. The screen-house experiment also showed that the rhizobacterial treatments significantly ( p < 0.05) enhanced different parameters associated with potato growth by up to 91% and established the potential of most of the isolates as alternative biofertilizers in potato cropping systems in Tanzania.
Whole-Genome Sequences of Three Plant Growth-Promoting Rhizobacteria Isolated from Solanum tuberosum L. Rhizosphere in Tanzania.
(American Society for Microbiology, 2020-05-14) Aloo, Becky; Mbega, Ernest; Makumba, Billy; Friedrich, Ines; Hertel, Robert; Daniel, Rolf
We present here the complete genome sequences of plant growth-promoting sp. strain MPUS7, sp. strain NGAS9, and sp. strain LUTT5, isolated from rhizosphere soils and tubers of potato ( L.) plants growing in the northern and southern highlands of Tanzania.